Sedimentary deposits and bioturbation in an Early Cretaceous subarctic stormy greenhouse shelf environment

This study of the Aptian lower part of the Carolinefjellet Formation in Svalbard, Norwegian high Arctic, is based on well cores and outcrop section in the Adventdalen area of Spitsbergen and reports on the deposits and bioturbation structures of an ancient subpolar marine shelf from a well-known period of global greenhouse climate. The study documents the sedimentation conditions and benthic fauna activity on a warm-water aggrading shelf subject to harsh Arctic wave climate and eurybatic base-level changes, with episodic bottom incursions of cold polar water. Lithofacies associations and 38 observed ichnotaxa represent subenvironments ranging from offshore to lower shoreface and hosting the Cruziana ichnofacies in its distal to proximal expression, with a brief mid-Aptian encroachment of middle shoreface zone with a distal expression of the Skolithos ichnofacies. The ichnofacies are variously impoverished compared to their archetypes. The sediment bioturbation intensity varies, but similar lithofacies associations show a comparable intensity throughout the stratigraphic succession, which indicates an ichnofauna ecology controlled by the seafloor hydraulic regime and oxygenation, and thus mainly by the wave climate and relative sea-level changes. Sandstone tempestites indicate high-frequency storms, commonly exceeding the magnitude of largest modern hurricane events. The study confirms that a change in global climate mode, such as the Early Cretaceous warming, entails extreme weather conditions.publishedVersio

Evaluation of Positioning Functionality in ASG EUPOS for Hydrography and Off-Shore Navigation

The paper discusses the ASG EUPOS services. There is presented an assessment of the possibility of using this system selected sites in hydrography and off-shore navigation tasks. Presented and analyzed the experiments were carried out in the port of Gdynia and on the Gulf of Gda?sk. The results obtaining in the work confirm the possibility of the position accuracy guaranteed by ASG EUPOS services. The obtained accuracy greatly exceeds the needs and requirements of coastal navigation and underwater mining and exploration of sea bottom

Long-range corrected DFT calculations of charge-transfer integrals in model metal-free phthalocyanine complexes

An assessment of several widely used exchange--correlation potentials in computing charge-transfer integrals is performed. In particular, we employ the recently proposed Coulomb-attenuated model which was proven by other authors to improve upon conventional functionals in the case of charge-transfer excitations. For further validation, two distinct approaches to compute the property in question are compared for a phthalocyanine dimer

Temporal imaging for ultra-narrowband few-photon states of light

Plenty of quantum information protocols are enabled by manipulation and detection of photonic spectro-temporal degrees of freedom via light-matter interfaces. While present implementations are well suited for high-bandwidth photon sources such as quantum dots, they lack the high resolution required for intrinsically narrow-band light-atom interactions. Here, we demonstrate far-field temporal imaging based on ac-Stark spatial spin-wave phase manipulation in a multimode gradient echo memory. We achieve spectral resolution of 20 kHz with MHz-level bandwidth and ultra-low noise equivalent to 0.023 photons, enabling operation in the single-quantum regime.Comment: 10 pages, 9 figure

Superradiant parametric conversion of spin waves

Atomic-ensemble spin waves carrying single-photon Fock states exhibit nonclassical many-body correlations in-between atoms. The same correlations are inherently associated with single-photon superradiance, forming the basis of a plethora of quantum light-matter interfaces. We devise a scheme allowing the preparation of spatially-structured superradiant states in the atomic two-photon cascade using spin-wave light storage. We thus show that long-lived atomic ground-state spin waves can be converted to photon pairs opening the way towards nonlinear optics of spin waves via multi-wave mixing processes.Comment: 9 pages, 6 figure

Mechanism of Hydrogen Sensing by AlGaN/GaN Pt-Gate Field Effect Transistors: Magnetoresistance Studies

Physical mechanism responsible for hydrogen sensing by AlGaN/GaN transistors was investigated. Original resistance studies versus magnetic fields (up to 8T) were used to determine precisely hydrogen induced change of carrier mobility and density. Results clearly show that the carrier mobility change is responsible for less than five percent and that the hydrogen sensitivity is mainly related (more than 95 percent) to the carrier density change. These results support the physical model that relates hydrogen sensing with a change of surface charges resulting in modification of the GaN depletion layer

Na[Li(NH2BH3)(2)] - the first mixed-cation amidoborane with unusual crystal structure

We describe the successful synthesis of the first mixed-cation (pseudoternary) amidoborane, Na[Li(NH2BH3)(2)], with theoretical hydrogen capacity of 11.1 wt%. Na[Li(NH2BH3)(2)] crystallizes triclinic (P (1) over bar ) with a = 5.0197(4) angstrom, b = 7.1203(7) angstrom, c = 8.9198(9) angstrom, alpha = 103.003(6)degrees, beta = 102.200(5)degrees, gamma = 103.575(5)degrees, and V = 289.98(5) angstrom(3) (Z = 2), as additionally confirmed by Density Functional Theory calculations. Its crystal structure is topologically different from those of its orthorhombic LiNH2BH3 and NaNH2BH3 constituents, with distinctly different coordination spheres of Li (3 N atoms and 1 hydride anion) and Na (6 hydride anions). Na[Li(NH2BH3)(2)], which may be viewed as a product of a Lewis acid (LiNH2BH3)/Lewis base (NaNH2BH3) reaction, is an important candidate for a novel lightweight hydrogen storage material. The title material decomposes at low temperature (with onset at 75 degrees C, 6.0% mass loss up to 110 degrees C, and an additional 3.0% up to 200 degrees C) while evolving hydrogen contaminated with ammonia