Correcting 100 years of misunderstanding: electric fields in superconductors, hole superconductivity, and the Meissner effect

From the outset of superconductivity research it was assumed that no electrostatic fields could exist inside superconductors, and this assumption was incorporated into conventional London electrodynamics. Yet the London brothers themselves initially (in 1935) had proposed an electrodynamic theory of superconductors that allowed for static electric fields in their interior, which they unfortunately discarded a year later. I argue that the Meissner effect in superconductors necessitates the existence of an electrostatic field in their interior, originating in the expulsion of negative charge from the interior to the surface when a metal becomes superconducting. The theory of hole superconductivity predicts this physics, and associated with it a macroscopic spin current in the ground state of superconductors ("Spin Meissner effect"), qualitatively different from what is predicted by conventional BCS-London theory. A new London-like electrodynamic description of superconductors is proposed to describe this physics. Within this theory superconductivity is driven by lowering of quantum kinetic energy, the fact that the Coulomb repulsion strongly depends on the character of the charge carriers, namely whether electron- or hole-like, and the spin-orbit interaction. The electron-phonon interaction does not play a significant role, yet the existence of an isotope effect in many superconductors is easily understood. In the strong coupling regime the theory appears to favor local charge inhomogeneity. The theory is proposed to apply to all superconducting materials, from the elements to the high $T_c$ cuprates and pnictides, is highly falsifiable, and explains a wide variety of experimental observations.Comment: Proceedings of the conference "Quantum phenomena in complex matter 2011 - Stripes 2011", Rome, 10 July -16 July 2011, to be published in J. Supercond. Nov. Mag

A Receptor Component of the Chloroplast Protein Translocation Machinery

The chloroplast outer envelope protein OEP86 functions as a receptor in precursor protein translocation into chloroplasts. Sequence analysis suggests that the precursor of OEP86 is directed to the chloroplast outer envelope by a cleavable, negatively charged, and unusually long amino-terminal peptide. This presequence is unlike other potential targeting signals and suggests the existence of another membrane insertion pathway. Insertion of precursor OEP86 required the hydrolysis of adenosine triphosphate and the existence of surface exposed chloroplast membrane components, and it was not competed by another precursor protein destined for the internal plastid compartments

Reproducing moral agents : the concept of human nature in an orthodox Jewish community.

SIGLEAvailable from British Library Document Supply Centre- DSC:DX177238 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Non-native populations of an invasive tree outperform their native conspecifics

Introduced plants often face new environmental conditions in their non-native ranges. To become invasive, they need to overcome several biotic and abiotic filters that may trigger adaptive changes in life-history traits, like postgermination processes. Such early life cycle traits may play a crucial role in the colonization and establishment success of invasive plants. As a previous study revealed that seeds of non-native populations of the woody Siberian elm, Ulmus pumila, germinated faster than those of native populations, we expected growth performance of seedlings to mirror this finding. Here, we conducted a common garden greenhouse experiment using different temperature and watering treatments to compare the biomass production of U. pumila seedlings derived from 7 native and 13 populations from two non-native ranges. Our results showed that under all treatments, non-native populations were characterized by higher biomass production and enhanced resource allocation to aboveground biomass compared to the native populations. The observed enhanced growth performance of non-native populations might be one of the contributing factors for the invasion success of U. pumila due to competitive advantages during the colonization of new sites.Fil: Hirsch, Heidi. Stellenbosch University, Centre for Invasion Biology, Department of Botany and Zoology; Sudáfrica. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; AlemaniaFil: Hensen, Isabell. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; Alemania. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; AlemaniaFil: Wesche, Karsten. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Alemania. Senckenberg Museum of Natural History Goerlitz; AlemaniaFil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Wypior, Catherina. Martin Luther University Halle-Wittenberg, Institute of Biology/Geobotany and Botanical Garden ; AlemaniaFil: Hartmann, Matthias. Charles University in Prague, Herbarium PRC & Department of Botany; República ChecaFil: von Wehrden, Henrik. Leuphana University, Institute of Ecology/Faculty of Sustainability, Centre of Methods; Alemania. Research Institute of Wildlife Ecology; Austri

An accurate and efficient algorithm for the computation of the characteristic polynomial of a general square matrix

An algorithm is presented for the efficient and accurate computation of the coefficients of the characteristic polynomial of a general square matrix. The algorithm is especially suited for the evaluation of canonical traces in determinant quantum Monte-Carlo methods.Comment: 8 pages, no figures, to appear in J. Comp. phy