Cornesti-Iarcuri - a Bronze Age town in the Romanian Banat?

©2011 Antiquity PublicationsA massive Late Bronze Age fortified settlement in Central Europe has been the subject of a new and exemplary investigation by excavation and site survey. This prehistoric enclosure, nearly 6km across, had a complex development, dense occupation and signs of destruction by fire. It can hardly be other than a capital city playing a role in the determinant struggles of its day — weighty and far reaching events of the European continent now being chronicled by archaeology.Funding for the project has been provided by the Fritz-Thyssen-Stiftung, K¨oln, the County Council of Timis¸ and the Muzeul Banatului Timis¸oara

Isocyanate emissions from pyrolysis of mattresses containing polyurethane foam

This study examined the emissions of powerful asthmatic agents called isocyanates from small-scale pyrolysis experiments of two common foams employed in mattress production such as flexible polyurethane foam (FPUF) and viscoelastic memory foam (VMF). A nitrogen atmosphere and five different temperatures, 300, 350, 400, 450 and 850 °C, were selected to carry out the experiments in order to evaluate the worst possible conditions for thermal degradation. A similar trend for both materials was found. At lower temperatures, diisocyanates were the most important products whereas at 850 °C monoisocyanates, and mainly isocyanic acid released mainly from the thermal cracking of diisocyanates evolved directly from the polymer chains. The total yields of isocyanates were in the range of 1.43–11.95 mg/m3 for FPUF at 300-850 °C and 0.05–6.13 mg/m3 for VMF, 300-850 °C. This difference could be a consequence of the lower amount of isocyanates employed in the VMF production which was confirmed by the nitrogen content of the foams, 5.95% FPUF vs. 3.34% in VMF. Additionally, a qualitative search for so far unknown isocyanates was performed in samples from the pyrolysis of FPUF at 300, 400 and 850 °C. It was confirmed that six different aminoisocyanates at 300 °C were evolved, whereas at 400 and 850 °C only five of them were detected. The general trend observed was a decrease of the aminoisocyanate levels with increasing pyrolysis temperature.Support for this work was provided by the Spanish Ministry of Education, Culture and Sport, by the CTQ2013-41006-R project from the Ministry of Economy and Competitiveness (Spain), the PROMETEOII/2014/007 project from the Valencian Community Government (Spain) and a mobility grant by the Spanish Ministry of Education, Culture and Sport (Spain) that enabled María Garrido to visit EMPA, in Switzerland

Dynamic fluid shifts induced by fetal bypass

ObjectiveFluid shifts have been suggested to occur with fetal bypass. The degree or mechanisms behind these volume changes (or location) have not been defined. We characterized the preceding and correlated the findings to plasma vasopressin concentrations, the critical peptide of osmoregulation.MethodsSeventeen ovine fetuses (105–111 days' gestation) were started on bypass and followed 2 hours after bypass. Hemodynamics and volume replacements needed to maintain minimum reservoir volume during bypass and normal physiologic parameters after bypass were recorded. Serial blood samples were collected to assess gas exchange and vasopressin levels. Changes in total tissue water content were measured for several organs and the placenta. Plasma volume, fluid shifts, and osmolarity were calculated.ResultsHematocrit values decreased by 15 minutes of bypass to 28% from 33% and then increased to 34% by 120 minutes after bypass, corresponding to a decreased fetal plasma volume of 79 to 72 mL/kg by 120 minutes after bypass. The majority of volume shifts (approximately 100 mL/kg) occurred during bypass, but additional volume replacements were required after bypass to maintain normal hemodynamics, resulting in overall losses of 0.8 mL · kg−1 · min−1. Losses were not accounted for by placental or organ edema. Vasopressin levels increased dramatically with bypass (39–51.5 pg/mL) and were strongly predicted by increased fetal plasma volumes (R2 = 0.90), whereas osmolarity was not significantly associated with plasma volumes.ConclusionFetal bypass leads to significant fluid shifts that correlate strongly with increasing vasopressin levels (but not changes in osmolarity). The placenta is not the primary site of volume loss. Rehydration of the fetus is necessary after bypass

Magnetism and superconductivity of strongly correlated electrons on the triangular lattice

We investigate the phase diagram of the \tj Model on a triangular lattice using a Variational Monte-Carlo approach. We use an extended set of Gutzwiller projected fermionic trial wave-functions allowing for simultaneous magnetic and superconducting order parameters. We obtain energies at zero doping for the spin-1/2 Heisenberg model in very good agreement with the best estimates. Upon electron doping (with a hopping integral $t<0$) this phase is surprisingly stable variationally up to $n\approx 1.4$, while the $d_{x^{2}-y^{2}}+i d_{xy}$ order parameter is rather weak and disappears at $n\approx 1.1$. For hole doping however the coplanar magnetic state is almost immediately destroyed and $d_{x^{2}-y^{2}}+i d_{xy}$ superconductivity survives down to $n\approx 0.8$. For lower $n$, between 0.2 and 0.8, we find saturated ferromagnetism. Moreover, there is evidence for a narrow spin density wave phase around $n\approx 0.8$. Commensurate flux phases were also considered, but these turned out {\em not} to be competitive at finite doping.Comment: 11 pages; 11 figure

Staggered-vorticity correlations in a lightly doped t-J model: a variational approach

We report staggered vorticity correlations of current in the d-wave variational wave function for the lightly-doped t-J model. Such correlations are explained from the SU(2) symmetry relating d-wave and staggered-flux mean-field phases. The correlation functions computed by the variational Monte Carlo method suggest that pairs are formed of holes circulating in opposite directions.Comment: ReVTeX, 4 pages, 3 figure

Vortex Charging Effect in a Chiral px±ipyp_x\pm i p_y-Wave Superconductor

Quasiparticle states around a single vortex in a $p_x\pm i p_y$-wave superconductor are studied on the basis of the Bogoliubov-de Gennes (BdG) theory, where both charge and current screenings are taken into account. Due to the violation of time reversal symmetry, there are two types of vortices which are distinguished by their winding orientations relative to the angular momentum of the chiral Cooper pair. The BdG solution shows that the charges of the two types of vortices are quite different, reflecting the rotating Cooper pair of the $p_x\pm i p_y$-wave paring state.Comment: 10 pages, 5 figures, revtex, to be published in Phys. Rev.

Lower Critical Field Hc1(T) and Pairing Symmetry Based on Eilenberger Theory

We quantitatively estimate different T-dependences of Hc1 between s wave and d wave pairings by Eilenberger theory. The T-dependences of Hc1(T) show quantitative deviation from those in London theory. We also study differences of Hc1(T) between p+ and p- wave pairing in chiral p wave superconductors. There, Hc1(T) is lower in p- wave pairing, and shows the same T-dependence as in s wave pairing.Comment: 2 pages, 1 figur

Ginzburg-Landau Theory for a p-Wave Sr_2RuO_4 Superconductor: Vortex Core Structure and Extended London Theory

Based on a two dimensional odd-parity superconducting order parameter for Sr_2RuO_4 with p-wave symmetry, we investigate the single vortex and vortex lattice structure of the mixed phase near H_{c1}. Ginzburg-Landau calculations for a single vortex show a fourfold structure with an orientation depending on the microscopic Fermi surface properties. The corresponding extended London theory is developed to determine the vortex lattice structure and we find near H_{c1} a centered rectangular vortex lattice. As the field is increased from H_{c1} this lattice continuously deforms until a square vortex lattice is achieved. In the centered rectangular phase the field distribution, as measurable through \mu-SR experiments, exhibits a characteristic two peak structure (similar to that predicted in high temperature and borocarbide superconductors).Comment: 12 pages, 7 figure

Strong Pinning and Plastic Deformations of the Vortex Lattice

We investigate numerically the dynamically generated plastic deformations of a 3D vortex lattice (VL) driven through a disorder potential with isolated, strong pinning centers (point-like or extended along the field direction). We find that the VL exhibits a very peculiar dynamical behavior in the plastic flow regime, in particular, topological excitations consisting of three or four entangled vortices are formed. We determine the critical current density $j_c$ and the activation energy for depinning $U_c$ in the presence of a finite density of strong pinning centers.Comment: 12 pages, TeX type, Postscript figure

Phase transition in the one-dimensional Kondo lattice model with attractive electron-electron interaction

The one-dimensional Kondo lattice model with attractive interaction among the conduction electrons is analyzed in the case of half-filling. It is shown that there are three distinct phases depending on the coupling constants of the model. Two phases have a spin and charge gap. While one shows a clear separation of the spin and charge excitation spectrum the other phase may be characterized as a band insulator type where both excitations are due to two-particle states. The third phase is gapless in both channels and has quasi long-range order in the spin and charge density wave correlation. In this phase the spin and charge excitations have again a clearly separated spectrum. For the analysis we discuss first two limiting cases. Then a density matrix renormalization group calculation on finite systems is applied to determine the phase diagram and the correlation functions in the gapped and gapless phase for general couplding constants.Comment: 9 pages, 7 Postscript figures, REVTe