Pressure-Induced Superconductivity in Sc to 74 GPa

Using a diamond anvil cell with nearly hydrostatic helium pressure medium we have significantly extended the superconducting phase diagram Tc(P) of Sc, the lightest of all transition metals. We find that superconductivity is induced in Sc under pressure, Tc increasing monotonically to 8.2 K at 74.2 GPa. The Tc(P) dependences of the trivalent d-electron metals Sc, Y, La, and Lu are compared and discussed within a simple s-d charge transfer framework.Comment: to be published in Phys. Rev. B (Brief Reports

Density of high area-to-mass objects in Geostationary and Medium Earth orbits through semi-analytical equations and differential algebra

This paper introduces and combines two novel techniques. Firstly, we introduce an efficient numerical method for the propagation of entire sets of initial conditions in the phase space and their associated phase space densities based on Differential Algebra (DA) techniques. Secondly, this DA density propagator is applied to a DA-enabled implementation of Semi-Analytical (SA) averaged dynamics, combining for the first time the power of the SA and DA techniques. While the DA-based method for the propagation of densities introduced in this paper is independent of the dynamical system under consideration, the particular combination of DA techniques with SA equations yields a fast and accurate method to propagate large clouds of initial conditions and their associated probability density functions very efficiently for long time. This enables the study of the long-term behavior of particles subjected to the given dynamics. To demonstrate the effectiveness of the proposed method, the evolution of a cloud of high area-to-mass objects in Medium Earth Orbit is reproduced considering the effects of solar radiation pressure, the Earth’s oblateness and luni-solar perturbations. The computational efficiency is demonstrated by propagating 10; 000 random samples taking snapshots of their state and density at evenly spaced intervals throughout the integration. The total time required for a propagation for 16 years in the dynamics is on the order of tens of seconds on a common desktop PC

Non-perturbative quark mass renormalization

We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the $\Lambda$--parameter in this theory with completely controlled errors.Comment: Talk given at LATTICE '97, 6 pages, Latex source, 7 eps figures, needs epsfi

Unter Mordverdacht: Differenzialdiagnose einer Arsenvergiftung

Zusammenfassung: Es wird ein Fall vorgestellt, der auf den ersten Blick an spektakuläre Arsenmorde der Vergangenheit anzuknüpfen scheint. Im Rahmen von Scheidungsstreitigkeiten zwischen einem 70-jährigen Mann und seiner knapp 30Jahre jüngeren Frau war es beim Betroffenen zu Symptomen einer Arsenvergiftung gekommen. Nach dem unerwarteten Tod seines Hundes hatte der Mann seinen Hausarzt aufgesucht, der bei einer Blutuntersuchung einen erhöhten Arsenspiegel feststellte. Bei chemisch-toxikologischen Analysen von Probenmaterial, das im Rahmen rechtsmedizinischer Untersuchungen der Betroffenen sowie einer Exhumierung des Hundes gewonnen wurde, fanden sich bei dem Mann und seiner Frau auffällig erhöhte Arsenspiegel. Die vorliegende Kasuistik unterstreicht eindrücklich die Wichtigkeit der Arsenspezifizierung in einem qualifizierten Labor im Fall einer erhöhten Arsenkonzentration in Probenmateria

Postweaning maternal care increases male chimpanzee reproductive success

International audienceHumans are unusual among animals for continuing to provision and care for their offspring until adulthood. This "prolonged dependency" is considered key for the evolution of other notable human traits, such as large brains, complex societies, and extended postreproductive lifespans. Prolonged dependency must therefore have evolved under conditions in which reproductive success is gained with parental investment and diminished with early parental loss. We tested this idea using data from wild chimpanzees, which have similarly extended immature years as humans and prolonged mother-offspring associations. Males who lost their mothers after weaning but before maturity began reproducing later and had lower average reproductive success. Thus, persistent motherimmature son associations seem vital for enhancing male reproductive success, although mothers barely provision sons after weaning. We posit that these associations lead to social gains, crucial for successful reproduction in complex social societies, and offer insights into the evolution of prolonged dependency

Infinite coupling duals of N=2 gauge theories and new rank 1 superconformal field theories

We show that a proposed duality [arXiv:0711.0054] between infinitely coupled gauge theories and superconformal field theories (SCFTs) with weakly gauged flavor groups predicts the existence of new rank 1 SCFTs. These superconformal fixed point theories have the same Coulomb branch singularities as the rank 1 E_6, E_7, and E_8 SCFTs, but have smaller flavor symmetry algebras and different central charges. Gauging various subalgebras of the flavor algebras of these rank 1 SCFTs provides many examples of infinite-coupling dualities, satisfying an intricate set of consistency checks. They also provide examples of N=2 conformal theories with marginal couplings but no weak-coupling limits.Comment: 12 page