A new inequality for the von Neumann entropy

Strong subadditivity of von Neumann entropy, proved in 1973 by Lieb and Ruskai, is a cornerstone of quantum coding theory. All other known inequalities for entropies of quantum systems may be derived from it. Here we prove a new inequality for the von Neumann entropy which we prove is independent of strong subadditivity: it is an inequality which is true for any four party quantum state, provided that it satisfies three linear relations (constraints) on the entropies of certain reduced states.Comment: 8 pages, 1 eps figur

Marshall-Peierls sign rule for excited states of the frustrated J1-J2 Heisenberg antiferromagnet

We present analytical and numerical calculations for some exited states of the frustrated J1-J2 spin-1/2 Heisenberg model for linear chains and square lattices. We consider the lowest eigenstates in the subspaces determined by the eigenvalue M of the spin operator S_total^z. Because of the reduced number of Ising basis states in the subspaces with higher M we are able to diagonalize systems with up to N=144 spins. We find evidence that the Marshall-Peierls sign rule survives for a relatively large frustration parameter J2.Comment: 7 pages, LaTeX, 4 eps figures, to appear in Physica

What Users Think about the Differences between Caffeine and Illicit/Prescription Stimulants for Cognitive Enhancement

Pharmacological cognitive enhancement (CE) is a topic of increasing public awareness. In the scientific literature on student use of CE as a study aid for academic performance enhancement, there are high prevalence rates regarding the use of caffeinated substances (coffee, caffeinated drinks, caffeine tablets) but remarkably lower prevalence rates regarding the use of illicit/prescription stimulants such as amphetamines or methylphenidate. While the literature considers the reasons and mechanisms for these different prevalence rates from a theoretical standpoint, it lacks empirical data to account for healthy students who use both, caffeine and illicit/prescription stimulants, exclusively for the purpose of CE. Therefore, we extensively interviewed a sample of 18 healthy university students reporting non-medical use of caffeine as well as illicit/prescription stimulants for the purpose of CE in a face-to-face setting about their opinions regarding differences in general and morally-relevant differences between caffeine and stimulant use for CE. 44% of all participants answered that there is a general difference between the use of caffeine and illicit/prescription stimulants for CE, 28% did not differentiate, 28% could not decide. Furthermore, 39% stated that there is a moral difference, 56% answered that there is no moral difference and one participant was not able to comment on moral aspects. Participants came to their judgements by applying three dimensions: medical, ethical and legal. Weighing the medical, ethical and legal aspects corresponded to the students' individual preferences of substances used for CE. However, their views only partly depicted evidence-based medical aspects and the ethical issues involved. This result shows the need for well-directed and differentiated information to prevent the potentially harmful use of illicit or prescription stimulants for CE

Low-lying excitations and thermodynamics of an antiferromagnetic Heisenberg fractal system of a dimension between one and two

We investigate a frustrated Heisenberg spin-1/2 antiferromagnet on a fractal lattice of dimension d=ln3/ln2 (Sierpinski gasket). Calculations were performed using (a) exact diagonalization of all eigenstates and eigenvectors for systems up to N=15 and (b) the Decoupled-Cell Quantum-Monte-Carlo method for systems up to N=366. We present the low-lying spectrum and the specific heat. The specific heat shows a second maximum in the low-temperature region. This behavior is similar to the behavior of the quantum Heisenberg antiferromagnet on a kagome lattice and suggests a disordered ground state and a spin gap in the considered system.Comment: 2 pages, LaTeX, 3 eps figures, to appear in JMM

Spiral cleavage and early embryology of a loxosomatid entoproct and the usefulness of spiralian apical cross patterns for phylogenetic inferences

Background: Among the four major bilaterian clades, Deuterostomia, Acoelomorpha, Ecdysozoa, and Lophotrochozoa, the latter shows an astonishing diversity of bodyplans. While the largest lophotrochozoan assemblage, the Spiralia, which at least comprises Annelida, Mollusca, Entoprocta, Platyhelminthes, and Nemertea, show a spiral cleavage pattern, Ectoprocta, Brachiopoda and Phoronida (the Lophophorata) cleave radially. Despite a vast amount of recent molecular phylogenetic analyses, the interrelationships of lophotrochozoan phyla remain largely unresolved. Thereby, Entoprocta play a key role, because they have frequently been assigned to the Ectoprocta, despite their differently cleaving embryos. However, developmental data on entoprocts employing modern methods are virtually non-existent and the data available rely exclusively on sketch drawings, thus calling for thorough re-investigation. Results: By applying fluorescence staining in combination with confocal microscopy and 3D-imaging techniques, we analyzed early embryonic development of a basal loxosomatid entoproct. We found that cleavage is asynchronous, equal, and spiral. An apical rosette, typical for most spiralian embryos, is formed. We also identified two cross-like cellular arrangements that bear similarities to both, a "molluscan-like" as well as an "annelid-like" cross, respectively. Conclusions: A broad comparison of cleavage types and apical cross patterns across Lophotrochozoa shows high plasticity of these character sets and we therefore argue that these developmental traits should be treated and interpreted carefully when used for phylogenetic inferences

Inelastic Multiple Scattering of Interacting Bosons in Weak Random Potentials

We develop a diagrammatic scattering theory for interacting bosons in a three-dimensional, weakly disordered potential. We show how collisional energy transfer between the bosons induces the thermalization of the inelastic single-particle current which, after only few collision events, dominates over the elastic contribution described by the Gross-Pitaevskii ansatz.Comment: 5 pages, 3 figures, very close to published versio

Europas Rolle in der Welt stärken: Optionen für ein kohärenteres Außenhandeln der Europäischen Union

'Die globale Handlungsfähigkeit der Europäischen Union wird durch die zunehmende Komplexität ihres außenpolitischen Instrumentariums und der hierbei beteiligten Institutionen merklich behindert. Der Vertrag über eine Verfassung für Europa widmet sich diesen grundlegenden Funktionsproblemen europäischer Außenpolitik. Er sieht mit der Einrichtung des Amtes eines Außenministers der Union und eines Europäischen Auswärtigen Dienstes eine effektive Zusammenführung der supranationalen und intergouvernementalen Elemente europäischen Außenhandelns vor, ohne jedoch deren grundsätzliches Spannungsverhältnis aufzulösen. Seit Mitte 2005 liegt diese Reform auf Eis. Andere, politisch wie rechtlich machbare Reformen für eine Verbesserung der außenpolitischen Kohärenz der EU auf der geltenden Vertragsgrundlage wurden ebenso zurückgestellt. Die Studie analysiert konkrete Maßnahmen für eine kohärentere Gestaltung europäischer Außenpolitik - in Erwartung der und als Vorbereitung auf die mit dem Verfassungsvertrag angestrebten Reformen. Die Empfehlungen zielen darauf ab, das Zusammenspiel aller europäischen Akteure zu optimieren, Entscheidungsläufe effizienter zu gestalten und interinstitutionelle Konfliktpotentiale zu minimieren. Für eine Stärkung der Rolle Europas in der Welt bedarf es darüber hinaus aber einer grundsätzlichen Richtungsentscheidung im weiteren Integrationsprozess. Will die EU im globalen Maßstab als schlagkräftiger Akteur ernst genommen werden, dann muss das Verhältnis zwischen supranationalen und zwischenstaatlichen Elementen der europäischen Außenpolitik bereits in der Umsetzung der im Verfassungsvertrag angelegten Reformen offen angesprochen werden.' (Autorenreferat

Assessing Noise Emissions of Different Drones in Representative Flight Maneuvers

This scientific publication focuses (i) on the specifications of the various drones used in this study, (ii) on the specifics of the varying flight maneuvers undertaken in the flight tests and (iii) on sharing the overall flight test experience. In the course of two different flight test campaigns conducted at DLRs National Experimental Test Center for Unmanned Aerial Systems in Cochstedt (Germany) in December 2020 and July 2021, numerous acoustical measurements have been recorded and later analyzed. Within this research initiative, the German Environmental Agency was responsible for providing the required measurement equipment, specifying the required UAV flight routes and analyzing the obtained research data

Poly[[diaqua-μ2-hydroxido-(μ7-2-phos­pho­nato­ethane­sulfonato)­dicopper(II)] trihydrate]

The crystal structure of the title compound, [Cu2(C2H4O6PS)(OH)(H2O)2]·3H2O, consists of two Cu2+ ions, one (O3PC2H4SO3)3− ion and one OH− ion, as well as five water mol­ecules, two of which are coordinated to Cu2+. The Cu2+ ions are coordinated by six O atoms. The CuO6 polyhedra are connected by μ- and μ3-O atoms into zigzag chains along the b axis. These chains are further connected by –CH2CH2– groups to form layers, in turn building a three-dimensional framework via hydrogen bonding