Phase transitions in a three dimensional U(1)×U(1)U(1) \times U(1) lattice London superconductor

We consider a three-dimensional lattice $U(1) \times U(1)$ superconductor in the London limit, with two individually conserved condensates. The problem, generically, has two types of intercomponent interactions of different characters. First, the condensates are interacting via a minimal coupling to the same fluctuating gauge field. A second type of coupling is the direct dissipationless drag represented by a local intercomponent current-current coupling term in the free energy functional. The interplay between these two types of interactions produces a number of physical effects not present in previously investigated $U(1)\times U(1)$ models with only one kind of intercomponent interaction. In this work, we present a study of the phase diagram of a $U(1) \times U(1)$ superconductor which includes both of these interactions. We study phase transitions and two types of competing paired phases which occur in this general model: (i) a metallic superfluid phase (where there is order only in the gauge invariant phase difference of the order parameters), (ii) a composite superconducting phase where there is order in the phase sum of the order parameters which has many properties of a single-component superconductor but with a doubled value of electric charge. We investigate the phase diagram with particular focus on what we call "preemptive phase transitions". These are phase transitions {\it unique to multicomponent condensates with competing topological objects}. A sudden proliferation of one kind of topological defects may come about due to a fluctuating background of topological defects in other sectors of the theory.Comment: 17 pages, 6 figures. Submitted to Physical Review

Observation of a metallic superfluid in a numerical experiment

We report the observation, in Monte Carlo simulations, of a novel type of quantum ordered state: {\it the metallic superfluid}. The metallic superfluid features ohmic resistance to counter-flows of protons and electrons, while featuring dissipationless co-flows of electrons and protons. One of the candidates for a physical realization of this remarkable state of matter is hydrogen or its isotopes under high compression. This adds another potential candidate to the presently known quantum dissipationless states, namely superconductors, superfluid liquids and vapours, and supersolids.Comment: 4 pages, 2 figures. Accepted for publication in Phys. Rev. Let

Effects of boundaries and density inhomogeneity on states of vortex matter in Bose--Einstein condensates at finite temperature

Most of the literature on quantum vortices predicting various states of vortex matter in three dimensions at finite temperatures in quantum fluids is based on an assumption of an extended and homogeneous system. It is well known not to be the case in actual Bose--Einstein condensates in traps which are finite systems with nonuniform density. This raises the question to what extent one can speak of different aggregate states of vortex matter (vortex lattices, liquids and tensionless vortex tangle) in these system. To address this point, in the present work we focus on the finite-size, boundaries and density inhomogeneity effects on thermal vortex matter in a Bose--Einstein condensate. To this end we perform Monte Carlo simulations on a model system describing trapped Bose--Einstein condensates. Throughout the paper, we draw on analogies with results for vortex matter obtained for extended systems. This work suggests that finiteness and intrinsic inhomogeneity of the system not withstanding, one nonetheless can approximately invoke the notion of distinct aggregate states of vortex matter realized at certain length scales. This might be helpful, in particular in search of possible new states of vortex matter in Bose--Einstein condensates with multiple components and different symmetries.Comment: 15 pages, 13 figures. Submitted to Physical Review A. High resolution pictures will be available in published versio

Strong diamagnetic response and specific heat anomaly above T_c in underdoped La_(2-x)Sr_xCuO_4

By measuring AC susceptibility using a very low amplitude of the AC field (<1 mG) it is shown that underdoped samples of La_(2-x)Sr_xCuO_4 (LASCO), are diamagnetic in a temperature region above T_c up to a temperature T^*. This behavior is only observed with AC fields along the c-axis whereas for fields in the ab-plane no diamagnetism above Tc was detected. The diamagnetism is almost frequency independent in the frequency range 0.1-10 kHz. At T* a broad step anomaly in the specific heat is inferred through measurements of the elastic constant c33. We suggest that the observed diamagnetism and the anomaly in the elastic constant are associated with the existence of phase incoherent Cooper pairs between Tc and T*.Comment: 5 pages 7 figures, to appear in Phys. rev

Conformation of 1,4-dihydropyridine — planar or boat-like?

AbstractThe geometry of the 1,4-dihydropyridine molecule was completely optimized employing three different ab initio basis sets (6–31 G*, 4–31 G, STO—3G). The most reliable 6–31G* basis set provides a very flat boat conformation which may easily undergo defolding to a planar ring arrangement. This result is discussed with respect to enzymatic redox cofactors and the pharmacological activity of dihydropyridine calcium antagonists

Demersal Fish Assemblages and Spatial Diversity Patterns in the Arctic-Atlantic Transition Zone in the Barents Sea

Direct and indirect effects of global warming are expected to be pronounced and fast in the Arctic, impacting terrestrial, freshwater and marine ecosystems. The Barents Sea is a high latitude shelf Sea and a boundary area between arctic and boreal faunas. These faunas are likely to respond differently to changes in climate. In addition, the Barents Sea is highly impacted by fisheries and other human activities. This strong human presence places great demands on scientific investigation and advisory capacity. In order to identify basic community structures against which future climate related or other human induced changes could be evaluated, we analyzed species composition and diversity of demersal fish in the Barents Sea. We found six main assemblages that were separated along depth and temperature gradients. There are indications that climate driven changes have already taken place, since boreal species were found in large parts of the Barents Sea shelf, including also the northern Arctic area. When modelling diversity as a function of depth and temperature, we found that two of the assemblages in the eastern Barents Sea showed lower diversity than expected from their depth and temperature. This is probably caused by low habitat complexity and the distance to the pool of boreal species in the western Barents Sea. In contrast coastal assemblages in south western Barents Sea and along Novaya Zemlya archipelago in the Eastern Barents Sea can be described as diversity “hotspots”; the South-western area had high density of species, abundance and biomass, and here some species have their northern distribution limit, whereas the Novaya Zemlya area has unique fauna of Arctic, coastal demersal fish. (see Information S1 for abstract in Russian)

Advice on fishing opportunities for Barents Sea capelin in 2024 — ICES subareas 1 and 2 excluding Division 2.a west of 5°W

Source at https://www.hi.no/hi/nettrapporter

Advice on fishing opportunities for Barents Sea capelin in 2024 — ICES subareas 1 and 2 excluding Division 2.a west of 5°W

publishedVersio

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Holmium Nanoparticles: Preparation and In Vitro Characterization of a New Device for Radioablation of Solid Malignancies

# The Author(s) 2010. This article is published with open access at Springerlink.com Purpose The present study introduces the preparation and in vitro characterization of a nanoparticle device comprising holmium acetylacetonate for radioablation of unresectable solid malignancies. Methods HoAcAc nanoparticles were prepared by dissolving holmium acetylacetonate in chloroform, followed by emulsification in an aqueous solution of a surfactant and evaporation of W. Bult: R. Varkevisser: P. R. Luijten: A. D. van het Schip