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• Springer  (1,717,634)
• American Institute of Physics (AIP)  (241,953)
• American Association for the Advancement of Science (AAAS)  (101,540)
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• Springer  (1,717,634)
• American Institute of Physics (AIP)  (241,953)
• American Association for the Advancement of Science (AAAS)  (101,540)
• Elsevier  (1,693,209)
• Wiley-Blackwell  (472,256)
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• 1
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Springer
Publication Date: 2019-10-18
Description: Plastic has become indispensable for human life. When plastic debris is discarded into waterways, these items can interact with organisms. Of particular concern are microscopic plastic particles (microplastics) which are subject to ingestion by several taxa. This review summarizes the results of cutting-edge research about the interactions between a range of aquatic species and microplastics, including effects on biota physiology and secondary ingestion. Uptake pathways via digestive or ventilatory systems are discussed, including (1) the physical penetration of microplastic particles into cellular structures, (2) leaching of chemical additives or adsorbed persistent organic pollutants (POPs), and (3) consequences of bacterial or viral microbiota contamination associated with microplastic ingestion. Following uptake, a number of individual-level effects have been observed, including reduction of feeding activities, reduced growth and reproduction through cellular modifications, and oxidative stress. Microplastic-associated effects on marine biota have become increasingly investigated with growing concerns regarding human health through trophic transfer. We argue that research on the cellular interactions with microplastics provide an understanding of their impact to the organisms’ fitness and, therefore, its ability to sustain their functional role in the ecosystem. The review summarizes information from 236 scientific publications. Of those, only 4.6% extrapolate their research of microplastic intake on individual species to the impact on ecosystem functioning. We emphasize the need for risk evaluation from organismal effects to an ecosystem level to effectively evaluate the effect of microplastic pollution on marine environments. Further studies are encouraged to investigate sublethal effects in the context of environmentally relevant microplastic pollution conditions.
Repository Name: EPIC Alfred Wegener Institut
Type: Book , NonPeerReviewed
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• 2
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Intelligent drug delivery systems have attracted great attention in the field of biomedicine and cancer diagnosis. In this work, a drug delivery system that can be gated by doxorubicin itself and together with pH-responsive ability has been designed and prepared based on the upconversion nanoparticles. The drug delivery system is a special core–shell structure, consisting of upconversion nanoparticle core and mesoporous silica shell. The new system tactfully bypasses the use of auxiliary capping agents and exhibits desirable drug release at pH = 5, enhancing HeLa cells inhibition. The introduction of Schiff base plays a key role in the process of achieving pH-responsive drug release. Moreover, upconversion nanoparticles could emit bright yellow-green fluorescence (540 nm) under the irradiation of near-infrared light (980 nm) for in vivo bioimaging. This characteristic provides the possibility of locating tumor tissues and real-time tracing drug delivery.〈/p〉
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Topics: Maschinenwesen, Werkstoffwissenschaften, Fertigungstechnik, Bergbau u. Hüttenwesen, Verkehrstechnik, Feinwerktechnik , Physics
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• 3
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Polylactic acid (PLA) is a biodegradable thermoplastic polymer that is presented as a good alternative to petroleum-derived plastics. Some of the major drawbacks of this material are its lack of thermal stability and rapid degradation in large-scale production; thus, special care must be taken during processing. To improve their properties, a reactive extrusion with a multi-epoxy chain extender (SAmfE) has been performed at pilot plant scale. The induced topological modifications produce a mixture of several types of non-uniform structures. Conventional chromatographic (SEC—static light scattering) or spectroscopic (nuclear magnetic resonance) techniques usually fail in characterizing non-uniform structures. A method for the classification of modified PLA samples based on a multivariate treatment of the spectral data obtained by Fourier-transform infrared spectroscopy, jointly with the application of feature extraction and classification algorithms, was applied in this study. The results of this work show the potential of the methodology proposed to improve quality control during manufacturing.〈/p〉
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• 4
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Despite the vast available literature on the synergistic action between zeolites and intumescent formulations, the influence of the acidity of the zeolite on the flame-retardant properties of the materials has not yet been properly addressed. This work investigates the effect of the concentration and the strength of the acidic sites of faujasite Y zeolites on their synergistic action with an intumescent formulation composed of ammonium polyphosphate (APP) and pentaerythritol (PER) in a polypropylene matrix. The results from the limiting oxygen index, cone calorimetry and glow-wire indicate that the zeolites with higher concentration of moderate strength acidic sites can catalyse more efficiently the reaction between APP and PER, which produces phosphate esters, precursors of 〈em〉char〈/em〉, enhancing the flame-retardant properties. However, an over increase in the acidic sites strength shows the opposite effect, as the zeolite can be prematurely deactivated during the initial steps of 〈em〉char〈/em〉 formation. Therefore, the increase in the concentration of the faujasite Y acidic sites with moderate strength might be a good strategy in order to obtain materials with better flame-retardant properties.〈/p〉
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• 5
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉By means of the CRYSTAL computer program package, first-principles calculations of polar ZrO-, Ca- and O-terminated CaZrO〈sub〉3〈/sub〉 (011) surfaces were performed. Our calculation results for polar CaZrO〈sub〉3〈/sub〉 (011) surfaces are compared with the previous ab initio calculation results for ABO〈sub〉3〈/sub〉 perovskite (011) and (001) surfaces. From the results of our hybrid B3LYP calculations, all upper-layer atoms on the ZrO-, Ca- and O-terminated CaZrO〈sub〉3〈/sub〉 (011) surfaces relax inwards. The only exception from this systematic trend is outward relaxation of the oxygen atom on the ZrO-terminated CaZrO〈sub〉3〈/sub〉 (011) surface. Different ZrO, Ca and O terminations of the CaZrO〈sub〉3〈/sub〉 (011) surface lead to a quite different surface energies of 3.46, 1.49, and 2.08 eV. Our calculations predict a considerable increase in the Zr–O chemical bond covalency near the CaZrO〈sub〉3〈/sub〉 (011) surface, both in the directions perpendicular to the surface (0.240〈em〉e〈/em〉) as well as in the plane (0.138〈em〉e〈/em〉), as compared to the CaZrO〈sub〉3〈/sub〉 (001) surface (0.102〈em〉e〈/em〉) and to the bulk (0.086〈em〉e〈/em〉). Such increase in the B–O chemical bond population from the bulk towards the (001) and especially (011) surfaces is a systematic trend in all our eight calculated ABO〈sub〉3〈/sub〉 perovskites.〈/p〉
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• 6
Publication Date: 2020
Description: 〈p〉1) The symbol “〈em〉w〈/em〉〈sub〉〈em〉f〈/em〉〈/sub〉” in Eq. (2) on p. 3458 denotes the weight fraction of HNTs in PVA/ST/HNT nanocomposites.〈/p〉
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• 7
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉The needle-like TiO〈sub〉2〈/sub〉 obtained by hydrothermal treatment combines with Graphene by adding cetyltrimethylammonium bromide (CTAB) as auxiliary dispersant. On this basis, the needle-like TiO〈sub〉2〈/sub〉/Graphene composite conductive material was prepared which is increasing the compatibility of conductive Graphene. The growth mechanism of the needle-like TiO〈sub〉2〈/sub〉/Graphene was discussed and supported by scanning electron microscopy, transmission electron microscopy and other test methods. Experimental results show that hydrothermal temperature has a great influence on the formation of needle-like TiO〈sub〉2〈/sub〉. The quick electron transportation properties between TiO〈sub〉2〈/sub〉 and Graphene make the TiO〈sub〉2〈/sub〉/Graphene have excellent conductive ability. Needle-like TiO〈sub〉2〈/sub〉 can facilitate electron transport on the layer of Graphene. The three-dimensional mesh structure formed by crisscross of needle-like TiO〈sub〉2〈/sub〉 is attached to the Graphene surface by the auxiliary effect of CTAB, is forming a conductive network to increase the transmission rate of electrons, so that the TiO〈sub〉2〈/sub〉/Graphene is endowed with good electrical conductivity. Finally, the resistivity of TiO〈sub〉2〈/sub〉/Graphene is as low as 1.655 × 10〈sup〉−3〈/sup〉 Ω m at 7 wt% Graphene, which conforms to the electrical conductive standard of the materials prepared by the factory.〈/p〉
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• 8
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉The application of Co-W-P plating technology in high-temperature package structure is advantageous from a point of structural reliability because Co-W-P metallization is known to deliver strong bonding to both high-temperature-compatible Ag-sintered joining and high-temperature-compatible encapsulation resins. However, Co-W-P, unlike a noble metal, has a potential risk of surface oxidation in the module fabrication process. This surface oxidation can result in a decrease in resin adhesion. In this paper, the effects of W content (7 wt%, 11 wt%, 21 wt%) in Co-W-P metallization on both the oxidation resistance and the resin adhesion were studied. The resin adhesion on the annealed Co-W-P metallization with a high W content (21 wt%) was found to be sufficiently strong even after 250 °C anneal for 1 h. This resin adhesion strength was not present in other Co-W-P metallization tests. SEM–EDS analysis revealed that the oxidization of the Co-W-P-metallized surface during the anneal process proceeded more slowly in the case of the Co-W-P metallization with a doping 21 wt% W. XPS analysis revealed that Co(OH)〈sub〉2〈/sub〉, necessary for a chemical reaction with the resin, exists mainly on the Co-W-P-metallized surface in the case of doping 21 wt% W, even after 250 °C anneal. XRD analysis revealed its structure to be a characteristic Co-W solid solution, unlike the structures found in other Co-W-P metallization. The findings in this study are significant for the promotion of Co-W-P metallization in the module fabrication process, as well as to the fundamental understanding of oxidation resistance and adhesion behavior on Co-W-P metallization.〈/p〉
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• 9
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Semiconductor nanocrystals (NCs) heavily doped with cation/anion vacancies or foreign metal ions can support localized surface plasmon resonance (LSPR) in the near-infrared (NIR) and mid-infrared (MIR) spectral wavelengths. Typically, nonstoichiometric copper sulfide Cu〈sub〉2−〈em〉x〈/em〉〈/sub〉S NCs with different 〈em〉x〈/em〉 values (0 〈 〈em〉x〈/em〉 ≤ 1) have attracted numerous attention because of hole-based, particle size, morphology, hole density and crystal phase-dependent LSPR. In spite of excited development of methodology for LSPR manipulation, systematic LSPR tuning of Cu〈sub〉2−〈em〉x〈/em〉〈/sub〉S NCs with a special crystal phase has been limited. Herein, roxbyite Cu〈sub〉1.8〈/sub〉S nanodisks (NDs) were selected as a model and their LSPR was readily tuned by particle size, hole density via chemical oxidation and reduction, self-assembly and disassembly in solution and plasmon coupling in multilayer films. Particle size, hole density and plasmon coupling severely affect their LSPR peak position and absorption intensity. Therefore, the ability of flexible LSPR tuning gifts roxbyite Cu〈sub〉1.8〈/sub〉S NDs great potential in plasmonic applications, including photocatalysis, photothermal agent, two-photon photochemistry and many others in NIR and MIR regions.〈/p〉
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• 10
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉A series of promising Ce–Co–Fe catalysts were successfully synthesized using a cetyl-trimethylammonium-bromide-assisted co-precipitation method and investigated for diesel soot combustion. The surface morphological and structural properties were systematically examined using various techniques: X-ray diffraction, scanning electron microscope, N〈sub〉2〈/sub〉 adsorption–desorption, Raman spectroscopy, temperature-programmed reduction and in situ diffuse reflection infrared Fourier transform spectroscopy. The catalyst–soot combustion activities were tested in O〈sub〉2〈/sub〉 and NO + O〈sub〉2〈/sub〉 using a temperature-programmed technique. Nanometer crystalline solid solutions were formed with high surface areas when the Fe and Co cations were co-doped in the ceria lattice. Transition metals doping played a key role in increasing oxygen vacancies and promoting the redox performance of Ce–Co–Fe catalysts. Co–Fe co-doping accelerated the oxidation of soot under both “tight” and “loose” contact conditions. Among all the ceria-based catalysts, Ce〈sub〉80〈/sub〉Co〈sub〉15〈/sub〉Fe〈sub〉5〈/sub〉 showed superior activity with 〈em〉T〈/em〉〈sub〉10〈/sub〉 = 256 °C and high selectivity with 〈span〉 〈span〉$$S_{{{\text{CO}}_{ 2} }} \, = \,100\%$$〈/span〉 〈/span〉 under tight a contact mode. The observed high catalytic activity following co-doping was proved to have occurred because of various reasons such as improved redox properties, increased oxygen vacancies and high surface area. The presence of NO in O〈sub〉2〈/sub〉 also promoted soot oxidation, which follows the NO〈sub〉2〈/sub〉-assisted mechanism. Moreover, the in situ DRIFTS performed under an isothermal condition in NO + O〈sub〉2〈/sub〉 confirmed the strong adsorption capacity for NO〈em〉x〈/em〉 species on the doped ceria catalyst.〈/p〉
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• 11
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Wearable flexible sensors based on fabrics possessing advantages of softness, flexibility and foldability have gained great attention nowadays. Here, a flexible assembled sensor is composed of one fabric coated with a certain circuit pattern by polyaniline (PANI) coating and another fabric with PANI/nano-silver coating. The sensor is delicately designed by face-to-face placing the conductive surfaces of two cotton fabrics to form an interpolation structure. The features of resultant sensor are confirmed by SEM, XRD and EDS tests. In addition, the dynamic response tests of the sensor show high sensitivity of 0.04–0.10 kPa〈sup〉−1〈/sup〉, high durability of 500 cycles, broad sensing range of about 0–20 kPa and quick response and recovery time of about 0.40 s, and the breaking strength is 25.00 MPa and the elongation at break is 19.00%. The sensor also can effectively monitor various forces and detect multiple human body movements. Thanks to the unique properties of the fabric and the superior performance of the sensor, we believe this mechanical sensor based on flexible fabrics will exhibit great potential for motion monitoring and vocal cord vibration recognition.〈/p〉
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• 12
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Polyvinylidene fluoride (PVDF) membranes were surface-modified via a simple coating method for improvement of the hydrophilicity performance. In this work, TP/PEI/PVDF modified membrane was successfully prepared by using tea polyphenol as a multifunctional coating. The physicochemical properties of membranes were characterized by Fourier transform infrared spectroscopy, X-ray energy-dispersive spectrometry, X-ray photoelectron spectroscopy scanning electron microscopy and atomic force microscopy. The water contact angle, pure water flux and methylene blue rejection ratio of membranes were investigated in detail. Compared with the pristine membrane, the water contact angle of the modified membrane decreased to 48.8°, and the rejection ratios were increased to 95.2% when the modified membrane was used to separate methylene blue. In addition, the modified membrane showed excellent antifouling performance in the experiment, and the flux recovery ratio still reached 84.6% after three fouling/washing cycles. In the oxidation experiment, the modified membranes were immersed in KMnO〈sub〉4〈/sub〉 solution for 6 h, and the results show that the water contact angle, pure water flux and methylene blue rejection of the modified membranes only have changed slightly. Therefore, this study could have a great potential for widening the application of membranes in the treatment of dye wastewater containing oxidants.〈/p〉
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• 13
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉The electronic structures of 〈span〉 〈span〉$$\hbox {Hf}_{1-x}\hbox {Zr}_{x}\hbox {S}_{3}$$〈/span〉 〈/span〉 and 〈span〉 〈span〉$$\hbox {Hf}_{1-x}\hbox {Zr}_{x}\hbox {Se}_{3}$$〈/span〉 〈/span〉 trichalcogenides are investigated by first-principles calculation. In particular, step change of Zr concentration is intensively investigated. Our calculations reveal that doping of Zr atoms increase the strength of cohesion between the atoms in 〈span〉 〈span〉$$\hbox {HfX}_ 3$$〈/span〉 〈/span〉 (X = S, Se) monolayers, and results in occurring of energetically more stable alloys. In addition, doping of Zr atoms in 〈span〉 〈span〉$$\hbox {HfS}_3$$〈/span〉 〈/span〉 causes band gap bowing, which means the curve of band gap values shows quadratic nonlinearities while change from semimetal to semiconductor is observed in 〈span〉 〈span〉$$\hbox {HfSe}_3$$〈/span〉 〈/span〉 case. The examined band structures indicate that 〈span〉 〈span〉$$\hbox {Hf}_{1-x}\hbox {Zr}_{x}\hbox {S}_{3}$$〈/span〉 〈/span〉 monolayers have very suitable band gap values for water splitting and also their band edge potentials have sufficiently higher or lower positions than the required potential values for the reduction or oxidation potentials. 〈/p〉
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• 14
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉The texture structure of the multi-crystalline silicon (mc-Si) pyramid was realized by a combination of acidic and alkaline etching. The results showed that the structure of the corrosion pits could be first obtained on the mc-Si surface by acid etching, and the subsequent alkaline etching could further transform the pits into a pyramid structure. The best solar cell obtained based on the textured structure showed superior photovoltaic property, and its photovoltaic conversion efficiency reached 18.17%, which was significantly higher than that of solar cell without texture structure. The improvement in efficiency was mainly owing to the light-trapping effect of texture structure, which was confirmed by the external quantum efficiency measurement. This work offers a simple way to prepare low-cost mc-Si solar cells with high performance.〈/p〉
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• 15
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Flexible unidirectional (UD) composite laminates are commonly being used for ballistic-resistant body armor. These laminates comprise UD layers, each constructed by laminating thin layers of high-performance fibers held in place using very low modulus binder resins, with the fibers in each layer oriented parallel to each other. As these materials are used in body armor, it is important to investigate their long-term reliability, particularly with regard to exposure to temperature and humidity as these are known causes of degradation in other commonly used body armor materials. This work investigates the tensile behavior of a poly(〈em〉p〈/em〉-phenylene terephthalamide), or PPTA flexible UD laminate aged for up to 150 days at accelerated aging conditions of 70 °C and 76% relative humidity. Tests were performed at three different crosshead displacement rates and three different gauge lengths. The effect of aging on the mechanical properties of the material was observed as less than 10% degradation in tensile strength, with a more significant reduction in longer specimens when tested at slower rates.〈/p〉
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• 16
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉In this work, the magnetic and transport properties of La〈sub〉0.7〈/sub〉Ca〈sub〉0.3〈/sub〉MnO〈sub〉3〈/sub〉 (LCMO) films are compared with films capped with Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉. The capping layers for films with the thicknesses of 50 nm and 100 nm broadened the metal–insulator transition, though they produced rather few changes to other properties. The results were dramatically different for a 20-nm-thick LCMO layer compared to other thicker films. The metal–insulator transition temperature increased from 160 to 200 K for capped LCMO film despite the fact that the capping layer reduced the magnitude of magnetization. The temperature of maximum magnetoresistance (MR) shifted from 115 to 185 K. However, its magnitude, 1500% at 5 T, remained unchanged due to capping. This behavior was attributed to atomic inter-diffusion at the LCMO/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 interface which resulted in the generation of Mn〈sup〉2+〈/sup〉 ions. These results are of great significance and suggest a promising future for both the fundamental research and device applications involving thin films of LCMO.〈/p〉
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• 17
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Magnesium-based alloys presented great potential for biodegradable implant materials. However, the poor mechanical properties and high corrosion rate blocked its extensive application. In this study, a new biodegradable Mg–Zn–Y–Gd–Zr alloy was fabricated and extruded. The microstructure, corrosion morphologies and corrosion products film of the as-cast, homogenized and as-extruded alloys were characterized by optical micrographs, scanning electron microscopy, X-ray diffraction and laser scanning confocal microscopy. Moreover, the corrosion mechanisms of the as-cast and as-extruded alloys were proposed, and the influencing factors of corrosion properties were discussed. The electrochemical test, immersion tests and corrosion morphologies demonstrated that the as-extruded alloy exhibited favorable corrosion properties. The as-cast and homogenized alloys displayed localized corrosion mode, and the as-extruded alloy displayed uniform corrosion mode. The Volta potential of the Mg〈sub〉3〈/sub〉(Y,Gd)〈sub〉2〈/sub〉Zn〈sub〉3〈/sub〉 phase relative to Mg matrix was measured by using Kelvin probe force microscopy. 〈/p〉
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• 18
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉2,4,6-Triamino-5-nitropyrimidine-1,3-dioxide (ICM-102) is a new high-energy crystal which has outstanding combination of performance, effects of three common small molecules H〈sub〉2〈/sub〉O, NH〈sub〉3〈/sub〉 and H〈sub〉2〈/sub〉S on its molecular, crystal and electronic structures, and elastic, optical and thermodynamic properties of the compound were studied by the first-principle calculation and Hirshfeld surface analysis in this work. The results showed that H〈sub〉2〈/sub〉O, NH〈sub〉3〈/sub〉 and H〈sub〉2〈/sub〉S do have significant effects on the structure and property of ICM-102, and different molecules made various influence on all kinds of properties. The low-sensitivity feature of ICM-102 was confirmed, and H〈sub〉2〈/sub〉O molecule was found to further increase the stability of ICM-102 crystal obviously by enriching different kinds of close contacts. While the stabilization effect of NH〈sub〉3〈/sub〉 and H〈sub〉2〈/sub〉S on the ICM-102 was weaker than that of H〈sub〉2〈/sub〉O and H〈sub〉2〈/sub〉O also improved the density, stiffness, fracture strength and ductility, absorption to purple, blue, green and yellow lights, and thermodynamics parameters of ICM-102, but it decreased the band gap, anisotropy, plasticity, absorption to near ultraviolet and orange, red and infrared lights, and dielectric constant. However, different to H〈sub〉2〈/sub〉O, NH〈sub〉3〈/sub〉 and H〈sub〉2〈/sub〉S reduced stiffness, fracture strength and ductility but increased the band gap of ICM-102. Besides, H〈sub〉2〈/sub〉S was found to completely eliminate the region where light cannot be transmitted in the solid crystal ICM-102. This study may be helpful for using small molecules to stabilize the structure and adjust the property of energetic materials. 〈/p〉
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Topics: Maschinenwesen, Werkstoffwissenschaften, Fertigungstechnik, Bergbau u. Hüttenwesen, Verkehrstechnik, Feinwerktechnik , Physics
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Springer
Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉Transition metal phosphides have been regarded as reliable supercapacitor electrode materials and extensively researched. In this work, a facile three-step way has been taken to synthesize NiCoP@NiCoP core–shell nanoarrays directly grown on carbon cloth, which was used as a high-performance supercapacitor electrode. Compared with the NiCo-LDH precursor and NiCoP nanowire and NiCoP nanosheet, NiCoP@NiCoP core–shell composite shows higher electrochemical performance owing to the integration of the advantages of phosphides and core–shell structure. To be specific, the as-fabricated NiCoP C–S electrode exhibits great electrochemical performance with high specific capacitance (1492.5 F g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉), good rate performance (68.82% of the initial specific capacitance at 15 A g〈sup〉−1〈/sup〉) and outstanding cycling stability (maintains 80.9% of the initial capacitances after 5000 cycles at 10 A g〈sup〉−1〈/sup〉). Moreover, the assembled NiCoP C–S//rGO asymmetric supercapacitor device delivers a high energy density of 48.13 Wh kg〈sup〉−1〈/sup〉 at the power density of 1125 W kg〈sup〉−1〈/sup〉 and it still retains 20.94 Wh kg〈sup〉−1〈/sup〉 at a high power density of 11250 W kg〈sup〉−1〈/sup〉, indicating its great possibility of practical application. 〈/p〉
Print ISSN: 0022-2461
Electronic ISSN: 1573-4803
Topics: Maschinenwesen, Werkstoffwissenschaften, Fertigungstechnik, Bergbau u. Hüttenwesen, Verkehrstechnik, Feinwerktechnik , Physics
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Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉In this work, a novel magnetic nanocomposite combining selenium nanoparticles (SeNPs) with iron oxide nanoparticles (IONPs) was synthesized for the first time, in which the size of the iron oxide nanoparticles was 7–12 nm, and nearly spherical or rod-like selenium nanoparticles were obtained according to the different pH values of the reaction mixtures. Selenium incorporation into iron oxide nanoparticles was improved by using a chitosan coating with pentasodium triphosphate as a crosslinking agent. The micromorphology, crystalline structure and magnetic properties of the nanocomposites were characterized by a transmission electron microscope, X-ray diffractometer and a superconducting quantum interference device. More importantly, the nanocomposites exhibited excellent anti-biofilm activity in the presence of an external magnetic field with significantly less toxicity toward human dermal fibroblast cells. The relative fraction of dead-to-live bacteria of the nanocomposites (400.0%) was much higher than that of SeNPs (51.6%) and IONPs (60.0%) by using ImageJ analysis. In this manner, the results of this study suggest that this presently created composite of selenium nanoparticles and iron oxide nanoparticles should be further studied (including in vivo assessment for blood compatibility and immune response) for a wide range of magnetically controlled biomedical applications.〈/p〉
Print ISSN: 0022-2461
Electronic ISSN: 1573-4803
Topics: Maschinenwesen, Werkstoffwissenschaften, Fertigungstechnik, Bergbau u. Hüttenwesen, Verkehrstechnik, Feinwerktechnik , Physics
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Publication Date: 2020
Description: 〈h3〉Abstract〈/h3〉 〈p〉The growing interest and rapid development of portable and flexible wearable electronics has significantly escalated the need of designing miniaturized on-chip energy storage and conversion units as power sources for smart electronic devices. Current aqueous microsupercapacitors suffer from a low energy density due to their small working potential, which limits their potential application. This study presents the fabrication of a 1.6 V flexible, aqueous asymmetric microsupercapacitor (AMSC) with 83% capacitance retention after 5000 cycles which designed by the integration and voltage balance of functionalized graphene-based cathode as a double-layer supercapacitive electrode and iodine-doped graphene anode as a pseudocapacitive electrode. The combination of electrostatic and faradic charge storage mechanism in this all-graphene-based AMSC enables the device to deliver an ultra-high energy–power density (4.75 mWh cm〈sup〉−3〈/sup〉 at 61.55 W cm〈sup〉−3〈/sup〉) and a stabilized performance even after 2000 repeated bending cycles, which suggests the promising potential of the all-graphene AMSC as a substantial power source for future flexible electronic devices.〈/p〉
Print ISSN: 0022-2461
Electronic ISSN: 1573-4803
Topics: Maschinenwesen, Werkstoffwissenschaften, Fertigungstechnik, Bergbau u. Hüttenwesen, Verkehrstechnik, Feinwerktechnik , Physics
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In:  Climate Dynamics, 52 (1-2). pp. 417-438.
Publication Date: 2019-03-28
Description: Beside its global effects, climate change is manifested in many regionally pronounced features mainly resulting from changes in the oceanic and atmospheric circulation. Here we investigate the influence of the North Atlantic SST on shaping the winter-time response to global warming. Our results are based on a long-term climate projection with the Max Planck Institute Earth System Model (MPI-ESM) to investigate the influence of North Atlantic sea surface temperature pattern changes on shaping the atmospheric climate change signal. In sensitivity experiments with the model’s atmospheric component we decompose the response into components controlled by the local SST structure and components controlled by global/remote changes. MPI-ESM simulates a global warming response in SST similar to other climate models: there is a warming minimum—or ”warming hole”—in the subpolar North Atlantic, and the sharp SST gradients associated with the Gulf Stream and the North Atlantic Current shift northward by a few a degrees. Over the warming hole, global warming causes a relatively weak increase in rainfall. Beyond this, our experiments show more localized effects, likely resulting from future SST gradient changes in the North Atlantic. This includes a significant precipitation decrease to the south of the Gulf Stream despite increased underlying SSTs. Since this region is characterised by a strong band of precipitation in the current climate, this is contrary to the usual case that wet regions become wetter and dry regions become drier in a warmer climate. A moisture budget analysis identifies a complex interplay of various processes in the region of modified SST gradients: reduced surface winds cause a decrease in evaporation; and thermodynamic, modified atmospheric eddy transports, and coastal processes cause a change in the moisture convergence. The changes in the the North Atlantic storm track are mainly controlled by the non-regional changes in the forcing. The impact of the local SST pattern changes on regions outside the North Atlantic is small in our setup.
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In:  In: Oceanographic and Biological Aspects of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer, Cham, Switzerland, pp. 401-418. ISBN 978-3-319-99416-1
Publication Date: 2018-12-14
Description: Coral reefs in the Red Sea belong to the most diverse and productive reef ecosystems worldwide, although they are exposed to strong seasonal variability, high temperature, and high salinity. These factors are considered stressful for coral reef biota and challenge reef growth in other oceans, but coral reefs in the Red Sea thrive despite these challenges. In the central Red Sea high temperatures, high salinities, and low dissolved oxygen on the one hand reflect conditions that are predicted for ‘future oceans’ under global warming. On the other hand, alkalinity and other carbonate chemistry parameters are considered favourable for coral growth. In coral reefs of the central Red Sea, temperature and salinity follow a seasonal cycle, while chlorophyll and inorganic nutrients mostly vary spatially, and dissolved oxygen and pH fluctuate on the scale of hours to days. Within these strong environmental gradients micro- and macroscopic reef communities are dynamic and demonstrate plasticity and acclimatisation potential. Epilithic biofilm communities of bacteria and algae, crucial for the recruitment of reef-builders, undergo seasonal community shifts that are mainly driven by changes in temperature, salinity, and dissolved oxygen. These variables are predicted to change with the progression of global environmental change and suggest an immediate effect of climate change on the microbial community composition of biofilms. Corals are so-called holobionts and associate with a variety of microbial organisms that fulfill important functions in coral health and productivity. For instance, coral-associated bacterial communities are more specific and less diverse than those of marine biofilms, and in many coral species in the central Red Sea they are dominated by bacteria from the genus Endozoicomonas. Generally, coral microbiomes align with ecological differences between reef sites. They are similar at sites where these corals are abundant and successful. Coral microbiomes reveal a measurable footprint of anthropogenic influence at polluted sites. Coral-associated communities of endosymbiotic dinoflagellates in central Red Sea corals are dominated by Symbiodinium from clade C. Some corals harbour the same specific symbiont with a high physiological plasticity throughout their distribution range, while others maintain a more flexible association with varying symbionts of high physiological specificity over depths, seasons, or reef locations. The coral-Symbiodinium endosymbiosis drives calcification of the coral skeleton, which is a key process that provides maintenance and formation of the reef framework. Calcification rates and reef growth are not higher than in other coral reef regions, despite the beneficial carbonate chemistry in the central Red Sea. This may be related to the comparatively high temperatures, as indicated by reduced summer calcification and long-term slowing of growth rates that correlate with ocean warming trends. Indeed, thermal limits of abundant coral species in the central Red Sea may have been exceeded, as evidenced by repeated mass bleaching events during previous years. Recent comprehensive baseline data from central Red Sea reefs allow for insight into coral reef functioning and for quantification of the impacts of environmental change in the region.
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In:  Marine Biology, 166 (3). Art.Nr. 33.
Publication Date: 2019-02-22
Description: Dosidicus gigas (the Humboldt squid) is a widely distributed and ecologically important predator in the eastern Pacific Ocean, but its mating behaviour is poorly understood. Individuals of this species have undergone a drastic change in size at maturity in the last years. We investigated mating activity of Humboldt squid in the Gulf of California in 2013, 2014, and 2015 by quantifying spermatangia deposited in the tissue of the buccal area. In 2015, we encountered the smallest mean mantle length of mature specimens recorded to date in the Gulf of California. In all years, numerous males were encountered that had been mated by other males. Spermatangia in males were deposited on the tissue in similar numbers and in the same location as normally occurs in females (the buccal area), suggesting that male-to-male mating behaviour is similar to male-to-female. This behaviour is referred to as same-sex sexual behaviour and has been described for various taxa, including other cephalopods. Overall similarity in mating frequency between males and females and in body size of mated individuals (in 2015) suggests non-discriminative and brief encounters with body size being a cue for mating. This mating strategy may be beneficial for males, as Humboldt squid live in groups where competition for mates is likely high. The energetic costs of male-to-male mating events may be counterbalanced by the fitness profits of indiscriminate mating behaviour.
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American Association for the Advancement of Science (AAAS)
In:  Science, 363 (6432). pp. 1193-1199.
Publication Date: 2019-04-04
Description: We quantify the oceanic sink for anthropogenic carbon dioxide (CO 2 ) over the period 1994 to 2007 by using observations from the global repeat hydrography program and contrasting them to observations from the 1990s. Using a linear regression–based method, we find a global increase in the anthropogenic CO 2 inventory of 34 ± 4 petagrams of carbon (Pg C) between 1994 and 2007. This is equivalent to an average uptake rate of 2.6 ± 0.3 Pg C year −1 and represents 31 ± 4% of the global anthropogenic CO 2 emissions over this period. Although this global ocean sink estimate is consistent with the expectation of the ocean uptake having increased in proportion to the rise in atmospheric CO 2 , substantial regional differences in storage rate are found, likely owing to climate variability–driven changes in ocean circulation.
Type: Article , PeerReviewed , info:eu-repo/semantics/article
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In:  Marine Biodiversity, 49 (2). pp. 1043-1046.
Publication Date: 2019-04-26
Description: An interactive (multi-access) global identification key (OncIdent) has been developed for the pelagic marine microcopepod family Oncaeidae and made accessible online. Details of the general approach and development of the key are given in Bottger-Schnack and Schnack (J Nat Hist 49:2727-2741, 2015). After beta-testing, new additions include illustrations for all species and feature attributes considered, plus a textual summary of each species' feature states in the key. Additional taxonomic notes are given where required, highlighting morphological or molecular genetic peculiarities or problems, with links to large data bases leading directly to more comprehensive information about each species. The present paper briefly reviews the taxonomic background for key construction, summarizes the opportunities and limitations of the current online version OncIdent2.0, and provides guidance for its practical use.
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Publication Date: 2019-04-10
Description: Our knowledge on distribution, habitats and behavior of Southern Ocean fishes living at water depths beyond scuba-diving limits is still sparse, as it is difficult to obtain quantitative data on these aspects of their biology. Here, we report the results of an analysis of seabed images to investigate species composition, behavior, spatial distribution and preferred habitats of demersal fish assemblages in the southern Weddell Sea. Our study was based on a total of 2736 high-resolution images, covering a total seabed area of 11,317 m2, which were taken at 13 stations at water depths between 200 and 750 m. Fish were found in 380 images. A total of 379 notothenioid specimens were recorded, representing four families (Nototheniidae, Artedidraconidae, Bathydraconidae, Channichthyidae), 17 genera and 25 species. Nototheniidae was the most speciose fam- ily, including benthic species (Trematomus spp.) and the pelagic species Pleuragramma antarctica, which was occasionally recorded in dense shoals. Bathydraconids ranked second with six species, followed by artedidraconids and channichthyids, both with five species. Most abundant species were Trematomus scotti and T. lepidorhinus among nototheniids, and Dol- loidraco longedorsalis and Pagetopsis maculatus among artedidraconids and channichthyids, respectively. Both T. lepi- dorhinus and P. maculatus preferred seabed habitats characterized by biogenous debris and rich epibenthic fauna, whereas T. scotti and D. longedorsalis were frequently seen resting on fine sediments and scattered gravel. Several fish species were recorded to make use of the three-dimensional structure formed by epibenthic foundation species, like sponges, for perching or hiding inside. Nesting behavior was observed, frequently in association with dropstones, in species from various families, including Channichthyidae (Chaenodraco wilsoni and Pagetopsis macropterus) and Bathydraconidae (Cygnodraco mawsoni).
Repository Name: EPIC Alfred Wegener Institut
Type: Article , NonPeerReviewed
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In:  In: Oceanographic and Biological Aspects of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer Oceanography Series . Springer, Cham, pp. 185-194.
Publication Date: 2018-12-11
Description: The deep-sea brines of the Red Sea are unusual extreme environments and form characteristically steep gradients across the brine-seawater interfaces. Due to their unusual nature and unique combination of physical-chemical conditions these interfaces provide an interesting source of new ﬁndings in the ﬁelds of geochemistry, geology, microbiology, biotechnology, virology, and general biology. The current chapter summarizes recent and new results in the study of geochemistry and life at the interfaces of brine-ﬁlled deeps of the Red Sea.
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In:  Atlas of Ecosystem Services
Publication Date: 2019-03-14
Type: inbook
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In:  A Mathematical Modeling Approach from Nonlinear Dynamics to Complex Systems
Publication Date: 2018-03-05
Type: inbook
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• 31
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In:  Atlas of Ecosystem Services
Publication Date: 2019-03-14
Type: inbook
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In:  In: Geological Setting, Palaeoenvironment and Archaeology of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer, Cham, Switzerland, pp. 221-232.
Publication Date: 2019-04-16
Description: Hydrothermal circulation at mid-ocean ridges and assimilation of hydrothermally altered crust or hydrothermal ﬂuids by rising magma can be traced by measuring chlorine (Cl) excess in erupted lavas. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an ultra-slow spreading ridge (maximum 1.6 cm yr−1 full spreading rate) by Cl, due to its saline seawater (40–42‰, cf. 35‰ in open ocean water), the presence of (hot) brine pools (up to 270‰ salinity and 68 °C) and the thick evaporite sequences that ﬂank the young rift. Absolute chlorine concentrations (up to 1300 ppm) and Cl concentrations relative to minor or trace elements of similar mantle incompatibility (e.g., K, Nb) are much higher in Red Sea basalts than in basalts from average slow spreading ridges. Mantle Cl/Nb concentrations can be used to calculate the Cl-excess, above the magmatic Cl, that is present in the samples. Homogeneous within-sample Cl concentrations, high Cl/H2O, the decoupling of Cl-excess from other trace elements and its independence of the presence of highly saline seaﬂoor brines at the site of eruption indicate that Cl is not enriched at the seaﬂoor. Instead we ﬁnd basaltic Cl-excess to be spatially closely correlated with evidence of hydrothermal activity, suggesting that deeper assimilation of hydrothermal Cl is the dominant Cl-enrichment process. A proximity of samples to both evaporite outcrops and bathymetric signs of volcanism on the seaﬂoor enhance Cl-excess in basalts. The basaltic Cl-excess can be used as a tracer together with new bathymetric maps as well as indications of hydrothermal venting (hot brine pools, metalliferous Hydrothermal circulation at mid-ocean ridges and assimilation of hydrothermally altered crust or hydrothermal ﬂuids by rising magma can be traced by measuring chlorine (Cl) excess in erupted lavas. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an ultra-slow spreading ridge (maximum 1.6 cm yr−1 full spreading rate) by Cl, due to its saline seawater (40–42‰, cf. 35‰ in open ocean water), the presence of (hot) brine pools (up to 270‰ salinity and 68 °C) and the thick evaporite sequences that ﬂank the young rift. Absolute chlorine concentrations (up to 1300 ppm) and Cl concentrations relative to minor or trace elements of similar mantle incompatibility (e.g., K, Nb) are much higher in Red Sea basalts than in basalts from average slow spreading ridges. Mantle Cl/Nb concentrations can be used to calculate the Cl-excess, above the magmatic Cl, that is present in the samples. Homogeneous within-sample Cl concentrations, high Cl/H2O, the decoupling of Cl-excess from other trace elements and its independence of the presence of highly saline seaﬂoor brines at the site of eruption indicate that Cl is not enriched at the seaﬂoor. Instead we ﬁnd basaltic Cl-excess to be spatially closely correlated with evidence of hydrothermal activity, suggesting that deeper assimilation of hydrothermal Cl is the dominant Cl-enrichment process. A proximity of samples to both evaporite outcrops and bathymetric signs of volcanism on the seaﬂoor enhance Cl-excess in basalts. The basaltic Cl-excess can be used as a tracer together with new bathymetric maps as well as indications of hydrothermal venting (hot brine pools, metalliferous sediments) to predict where hydrothermal venting or now inactive hydrothermal vent ﬁelds can be expected. Sites of particular interest for future hydrothermal research are the Mabahiss Deep, the Thetis-HadarbaHatiba Deeps and Shagara-Aswad-Erba Deeps (especially their large axial domes), and Poseidon Deep. Older hydrothermal vent ﬁelds may be present at the Nereus and Suakin Deeps. These sites signiﬁcantly increase the potential of hydrothermal vent ﬁeld prospection in the Red Sea.
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In:  In: Geological Setting, Palaeoenvironment and Archaeology of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer, Cham, Switzerland, pp. 37-52. ISBN 978-3-319-99407-9
Publication Date: 2019-04-16
Type: Book chapter , NonPeerReviewed
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In:  Springer Oceanography Book series . Springer, Cham, Switzerland, 550 pp. ISBN 978-3-319-99417-8
Publication Date: 2018-12-14
Description: This book includes invited contributions presenting the latest research on the oceanography and environment of the Red Sea. In addition to covering topics relevant to research in the region and providing insights into marine science for non-experts, it is also of interest to those involved in the management of coastal zones and encourages further research on the Red Sea
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In:  Marine Biology, 166 (3). Art.Nr. 30.
Publication Date: 2019-02-11
Description: The present study details the effects of basin-scale hydrographic characteristics of the Red Sea on the macroecology of Chaetognatha, a major plankton component in the pelagic realm. The hydrographic attributes and circulation of the Red Sea as a result of its limited connection with the northern Indian Ocean make it a unique ecohydrographic region in the world ocean. Here, we aimed to identify the prime determinants governing the community structure and vertical distribution of the Cheatognatha in this ecologically significant world ocean basin. The intrusion of Gulf of Aden Water influenced the Chaetognatha community composition in the south, whereas the overturning circulation altered their vertical distribution in the north. The existence of hypoxic waters (〈 100 µmol kg−1) at mid-depth also influenced their vertical distribution. The detailed evaluation of the responses of the different life stages of Chaetognatha revealed an increased susceptibility of adult individuals to hypoxic waters compared to immature stages. Higher oxygen demands of the adults for the egg and sperm production might have prevented them from inhabiting the oxygen-deficient mid-depth zones. The carbon and nitrogen content of the Copepoda and Chaetognatha communities and the quantification of the predation impact of Chaetognatha on Copepoda based on the feeding rate helped in corroborating the significant trophic link between these two prey–predator taxa. The observed influences of physical and chemical attributes on the distribution of Chaetognatha can be used as a model example for the role of the hydrography on the zooplankton community of the Red Sea.
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In:  Climate Dynamics, 52 (3-4). pp. 1505-1531.
Publication Date: 2019-03-20
Description: Climate model components involve both high-dimensional input and output fields. It is desirable to efficiently generate spatio-temporal outputs of these models for applications in integrated assessment modelling or to assess the statistical relationship between such sets of inputs and outputs, for example, uncertainty analysis. However, the need for efficiency often compromises the fidelity of output through the use of low complexity models. Here, we develop a technique which combines statistical emulation with a dimensionality reduction technique to emulate a wide range of outputs from an atmospheric general circulation model, PLASIM, as functions of the boundary forcing prescribed by the ocean component of a lower complexity climate model, GENIE-1. Although accurate and detailed spatial information on atmospheric variables such as precipitation and wind speed is well beyond the capability of GENIE-1’s energy-moisture balance model of the atmosphere, this study demonstrates that the output of this model is useful in predicting PLASIM’s spatio-temporal fields through multi-level emulation. Meaningful information from the fast model, GENIE-1 was extracted by utilising the correlation between variables of the same type in the two models and between variables of different types in PLASIM. We present here the construction and validation of several PLASIM variable emulators and discuss their potential use in developing a hybrid model with statistical components.
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In:  Climatic Change .
Publication Date: 2019-03-04
Description: Climate engineering (CE) deployment would alter prevailing relationships between Earth system variables, making indicators and metrics used so far in the climate change assessment context less appropriate to assess CE measures. Achieving a comprehensive CE assessment requires a systematic and transparent reevaluation of the indicator selection process from Earth system variables. Here, we provide a first step towards such a systematic assessment of changes in correlations between Earth system variables following simulated deployment of different CE methods. We therefore analyze changes in the correlation structure of a broad set of Earth system variables for two conventional climate change scenarios without CE and with three idealized CE model experiments: (i) solar radiation management, (ii) large-scale afforestation, and (iii) ocean alkalinity enhancement. First, we investigate how the three CE scenarios alter prevailing correlations between Earth system variables when compared to an intermediate-high and a business-as-usual future climate change scenario. Second, we contrast the indicators identified for the non-CE climate change scenarios and the indicators identified when all five scenarios are considered. Finally, we use the identified indicator sets for an evaluation of the five climate change scenarios. We find that the additional indicators provide valuable information for the assessment of the CE measures, and their application hence allows for a more comprehensive and a comparative assessment of the mitigation and CE deployment scenarios.
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Publication Date: 2019-03-04
Description: Many marine gastropods show species-specific behavioral responses to different predators, but less is known about the mechanisms influencing differences or similarities in specific responses. Herein, we examined whether two limpet species, Scurria viridula (Lamarck, 1819) and Fissurella latimarginata (Sowerby, 1835), show species- and size-specific similarities or differences in their reaction to predatory seastars and crabs. Both S. viridula and F. latimarginata reacted to their main seastar predators with escape responses. In contrast, both limpets did not flee from common crab predators, but, instead, fastened to the rock. All tested size classes of both limpet species reacted in a similar way, escaping from seastars, but clamping onto the rock in response to crabs. Limpets could reach velocities sufficient to outrun their specific seastar predators, but they were not fast enough to escape crabs. Experiments with limpets of different shell conditions (with and without shell damage) indicated that F. latimarginata with a damaged shell showed “accommodation movements” (slow movements away from stimulus) in response to predatory crabs. In contrast, intact F. latimarginata and all S. viridula (intact and damaged) clamped the shell down to the substratum. The response details suggest that the keyhole limpet F. latimarginata is more sensitive to predators (faster reaction time, longer escape distances, and higher proportion of reacting individuals) than S. viridula, possibly because the morphology of F. latimarginata (the relationship of its shell size and structure to its total body size) makes this species more vulnerable to predation. Our study suggests that chemically mediated effects of seastar and crab predators result in contrasting behavioral responses of both limpet species, independent of their habitat and morphology. Despite the different characteristics of the limpet species and the identity of predators, the limpets react in comparable ways to similar predator types.
Repository Name: EPIC Alfred Wegener Institut
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In:  Climatic Change, 153 (3). pp. 305-322.
Publication Date: 2019-05-16
Description: Climate engineering (CE) deployment would alter prevailing relationships between Earth system variables, making indicators and metrics used so far in the climate change assessment context less appropriate to assess CE measures. Achieving a comprehensive CE assessment requires a systematic and transparent reevaluation of the indicator selection process from Earth system variables. Here, we provide a first step towards such a systematic assessment of changes in correlations between Earth system variables following simulated deployment of different CE methods. We therefore analyze changes in the correlation structure of a broad set of Earth system variables for two conventional climate change scenarios without CE and with three idealized CE model experiments: (i) solar radiation management, (ii) large-scale afforestation, and (iii) ocean alkalinity enhancement. First, we investigate how the three CE scenarios alter prevailing correlations between Earth system variables when compared to an intermediate-high and a business-as-usual future climate change scenario. Second, we contrast the indicators identified for the non-CE climate change scenarios and the indicators identified when all five scenarios are considered. Finally, we use the identified indicator sets for an evaluation of the five climate change scenarios. We find that the additional indicators provide valuable information for the assessment of the CE measures, and their application hence allows for a more comprehensive and a comparative assessment of the mitigation and CE deployment scenarios.
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Publication Date: 2019-04-23
Description: Author Posting. © The Author(s), 2019. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in , Zakroff, C., Mooney, T.A. & Berumen, M.L. Dose-dependence and small-scale variability in responses to ocean acidification during squid, Doryteuthis pealeii, development. Marine Biology, (2019), 166: 62. doi:10.1007/s00227-019-3510-8.
Description: Coastal squids lay their eggs on the benthos, leaving them to develop in a dynamic system that is undergoing rapid acidification due to human influence. Prior studies have broadly investigated the impacts of ocean acidification on embryonic squid, but have not addressed the thresholds at which these responses occur or their potential variability. We raised squid, Doryteuthis pealeii (captured in Vineyard Sound, Massachusetts, USA: 41° 23.370N 70° 46.418´W), eggs in three trials across the breeding season (May - September, 2013) in a total of six chronic pCO2 exposures (400, 550, 850, 1300, 1900, and 2200 ppm). Hatchlings were counted and subsampled for mantle length, yolk volume, hatching time, hatching success, and statolith morphology. New methods for analysis of statolith shape, rugosity, and surface degradation were developed and are presented (with code). Responses to acidification (e.g., reduced mantle lengths, delayed hatching, and smaller, more degraded statoliths) were evident at ~ 1300 ppm CO2. However, patterns of physiological response and energy management, based on comparisons of yolk consumption and growth, varied among trials. Interactions between pCO2 and hatching day indicated a potential influence of exposure time on responses, while interactions with culture vessel highlighted the substantive natural variability within a clutch of eggs. While this study is consistent with, and expands upon, previous findings of sensitivity of the early life stages to acidification, it also highlights the plasticity and potential for resilience in this population of squid.
Description: This material was based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1122374 to CZ. This project was funded by National Science Foundation Grant No. 1220034 to TAM.
Description: 2020-04-19
Keywords: cephalopod ; embryo ; hypercapnia ; paralarvae ; statolith ; stress
Repository Name: Woods Hole Open Access Server
Type: Preprint
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In:  Hydrobiologia, 832 (1). pp. 215-233.
Publication Date: 2019-06-06
Description: Differences in habitat and diet between species are often associated with morphological differences. Habitat and trophic adaptation have therefore been proposed as important drivers of speciation and adaptive radiation. Importantly, habitat and diet shifts likely impose changes in exposure to different parasites and infection risk. As strong selective agents influencing survival and mate choice, parasites might play an important role in host diversification. We explore this possibility for the adaptive radiation of Lake Tanganyika (LT) cichlids. We first compare metazoan macroparasites infection levels between cichlid tribes. We then describe the cichlids’ genetic diversity at the major histocompatibility complex (MHC), which plays a key role in vertebrate immunity. Finally, we evaluate to what extent trophic ecology and morphology explain variation in infection levels and MHC, accounting for phylogenetic relationships. We show that different cichlid tribes in LT feature partially non-overlapping parasite communities and partially non-overlapping MHC diversity. While morphology explained 15% of the variation in mean parasite abundance, trophic ecology accounted for 16% and 22% of the MHC variation at the nucleotide and at the amino acid level, respectively. Parasitism and immunogenetic adaptation may thus add additional dimensions to the LT cichlid radiation.
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In:  Climate Dynamics, 52 (5-6). pp. 3489-3501.
Publication Date: 2019-05-28
Description: The spatial pattern of the first mode of interannual variability associated with the East Asian summer monsoon (EASM), obtained from a multivariate Empirical Orthogonal Functions (MV-EOF) analysis, corresponds to the Pacific–Japan (PJ) pattern and is referred to as the PJ-mode. The present study investigates the interannual variation of the PJ-mode from the perspective of the intraseasonal timescale. In particular, the impact of the Madden–Julian oscillation (MJO) on the interannual variation of the PJ-mode is investigated. The results show that the MJO has a significant influence on the interannual variation of the PJ-mode mainly in the lower troposphere (850 hPa) and that the former accounts for approximately 11% of the amplitude of the latter. The major part of the contribution comes from a change in frequency of the different phases of the MJO, especially that of MJO phase 6. This suggests that intraseasonal variation of the convection anomalies over the tropical eastern Indian and western Pacific Oceans plays an important role in the interannual variation of the PJ-mode. In addition, MJO phase 7 also contributes to the interannual variability of the PJ-mode, in this case induced by both the change in frequency and the change in circulation anomalies associated with MJO phase 7.
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In:  Climate Dynamics, 52 (9-10). pp. 5585-5604.
Publication Date: 2019-05-28
Description: Solar signals in the atmosphere and the ocean, especially in tropopause temperatures and lower stratospheric water vapour are investigated using recent observational and reanalyses data sets for the period from 1958 through 2013. Previous observational and modeling studies demonstrated solar influences in the lower stratosphere resembling a positive Northern Annular Mode due to the top-down mechanism involving enhanced solar UV radiation in the stratosphere during solar maxima and dynamical amplification mechanisms in the atmosphere. We found that these stratospheric changes might propagate down to the troposphere and become zonally asymmetric with characteristic pressure and wind pattern over the North Atlantic and North Pacific. Such changes in tropospheric circulation are related to anomalous positive SST anomalies in the central Pacific which resemble an El Niño Modoki event. We show for the first time with ocean reanalysis data that these SST anomalies are amplified by a positive feedback through oceanic subsurface currents and heat transport in the equatorial Pacific. Anomalous warm SSTs in the equatorial central Pacific change the zonal SST gradient and lead to anomalous westerly winds and currents in the western Pacific and easterly winds and currents in the eastern Pacific. This indicates a convergence and less upwelling and therefore enhances the positive SST anomalies in the equatorial central Pacific. Such a positive feedback results in a peak of El Niño Modoki events about 2 years after the solar maximum. These solar-induced signals in the ocean in turn modify the circulation and convection in the troposphere, resulting in lagged solar signals of anomalous high tropopause heights and negative anomalies in tropopause temperatures as well as in lower stratospheric water vapour over the equatorial Pacific which are in agreement with a time evolving solar-induced El Niño Modoki-like SST pattern. We demonstrate a solar modulation of intrinsic decadal climate variability over the Pacific which is amplified by positive feedbacks between the ocean and the atmosphere.
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In:  Natural Gas Engines: For Transportation and Power Generation | Energy, Environment, and Sustainability
Publication Date: 2019-06-14
Description: Lean-burn natural gas engines can be used to reduce exhaust emissions significantly. However, as the mixture is leaned out, the occurrence of extinction and incomplete combustion increases, resulting in poor performance and stability, as well as elevated levels of unburned hydrocarbon (UHC) and nitrogen oxides (NOx) emissions. The partially stratified charge (PSC) method can be used to mitigate these issues, while extending the lean misfire limit (LML) beyond its equivalent, homogeneous level. In this chapter, the PSC ignition and combustion processes are examined following a comprehensive experimental and numerical approach. Experiments are conducted in an idealized PSC configuration, using a constant volume combustion chamber (CVCC), to identify the principle enabling mechanisms of the PSC methodology. Engine tests conducted in a single-cylinder research engine (SCRE) demonstrate the feasibility of various PSC implementations in improving performance and emission characteristics in real-world settings. Complementary numerical analyses for the CVCC are obtained through large eddy simulations (LES), while Reynolds-averaged Navier?Stokes (RANS) simulations are conducted for SCRE with reduced chemical kinetics. The corresponding simulated results provide additional insights in characterizing the effect of fuel stratification on flame kernel maturation and flame propagation, the interplay between chemistry and turbulence at different overall air?fuel ratios, as well as formation of major pollutant species.
Language: English
Type: http://purl.org/eprint/type/BookItem
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In:  Journal of Applied Phycology, 31 (3). pp. 1845-1854.
Publication Date: 2019-06-13
Description: Diseases increasingly threaten aquaculture of kelps and other seaweeds. At the same time, protection concepts that are based upon application of biocides are usually not applicable, as such compounds would be rapidly diluted in the sea, causing ecological damage. An alternative concept could be the application of immune stimulants to prevent and control diseases in farmed seaweeds. We here present a pilot study that investigated the effects of oligoalginate elicitation on juvenile and adult sporophytes of Saccharina japonica cultivated in China and on adult sporophytes of Saccharina latissima cultivated in Germany. In two consecutive years, treatment with oligoalginate clearly reduced the detachment of S. japonica juveniles from their substrate curtains during the nursery stage in greenhouse ponds. Oligoalginate elicitation also decreased the density of endobionts and the number of bacterial cells on sporophytes of S. latissima that were cultivated on sea-based rafts. However, the treatment increased the susceptibility of kelp adults to settlement of epibionts (barnacles in Germany and filamentous algal epiphytes in China). In addition, oligoalginate elicitation accelerated the aging of S. japonica adults. Based upon these findings, oligoalginate elicitation could be a feasible way to provide “environmentally friendly” protection of kelp juveniles in nurseries. The same treatment causes not only beneficial, but also unwanted effects in adult kelp sporophytes. Therefore, it is not recommended as a treatment after the juvenile stage is completed. Future tests with other elicitors and other cultivated seaweed species may allow for the development of more feasible applications of targeted defense elicitation in seaweed aquaculture.
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In:  Computational Geosciences, 23 (2). pp. 355-372.
Publication Date: 2019-06-14
Description: Methane gas hydrates have increasingly become a topic of interest because of their potential as a future energy resource. There are significant economical and environmental risks associated with extraction from hydrate reservoirs, so a variety of multiphysics models have been developed to analyze prospective risks and benefits. These models generally have a large number of empirical parameters which are not known a priori. Traditional optimization-based parameter estimation frameworks may be ill-posed or computationally prohibitive. Bayesian inference methods have increasingly been found effective for estimating parameters in complex geophysical systems. These methods often are not viable in cases of computationally expensive models and high-dimensional parameter spaces. Recently, methods have been developed to effectively reduce the dimension of Bayesian inverse problems by identifying low-dimensional structures that are most informed by data. Active subspaces is one of the most generally applicable methods of performing this dimension reduction. In this paper, Bayesian inference of the parameters of a state-of-the-art mathematical model for methane hydrates based on experimental data from a triaxial compression test with gas hydrate-bearing sand is performed in an efficient way by utilizing active subspaces. Active subspaces are used to identify low-dimensional structure in the parameter space which is exploited by generating a cheap regression-based surrogate model and implementing a modified Markov chain Monte Carlo algorithm. Posterior densities having means that match the experimental data are approximated in a computationally efficient way.
Type: Article , PeerReviewed , info:eu-repo/semantics/article
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In:  Marine Biology, 166 (7). Art.Nr. 85.
Publication Date: 2019-06-21
Description: Reproductive systems of rare adult specimens of the deep-sea squid genera Chiroteuthis, Mastigoteuthis, Liocranchia, and Bathoteuthis were collected in 2006 and 2015 in the different research surveys in the Atlantic Ocean between 46 degrees 40'S and 17 degrees 11'N. Whole squids were preserved in 4% buffered formaldehyde solution, subsequently transferred into 70% ethanol and studied in laboratory condition providing initial observations on spawning pattern in these animals. The potential fecundity of Ch. cf. joubini was similar to 45,000-50,000, the maximum egg size was 1.6-1.7 mm, while those of M. agassizii were similar to 8000-16,000 and 1.7-1.9 mm respectively. A maturing female of B. skolops had similar to 4800 eggs of which some similar to 1200 were atretic. The ovary of a spent L. reinhardti contained similar to 116,500 post-ovulatory follicles and no residual egg. Mature females of Chiroteuthis and Mastigoteuthis had spematangia implanted externally in the mantle, whereas Liocranchia had a specialised spermatangia receptacle on the inside of the mantle. Reproductive adaptations of these genera are discussed in relation to spawning habits of other deep-sea squids. Synchronous ovulation was found to be a prevailing type of the gonad development with all eggs being spawned as a single batch, with ot without brooding. In some species, this single batch is not released at once but in several consequent portions exhibiting 'extended synchronous' spawning.
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In:  Climate Dynamics, 53 (1-2). pp. 1111-1124.
Publication Date: 2019-06-27
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In:  Microbial Ecology .
Publication Date: 2019-06-27
Description: Biodiversity is generally believed to be a main determinant of ecosystem functioning. This principle also applies to the microbiome and could consequently contribute to host health. According to ecological theory, communities are shaped by top predators whose direct and indirect interactions with community members cause stability and diversity. Bdellovibrio and like organisms (BALOs) are a neglected group of predatory bacteria that feed on Gram-negative bacteria and can thereby influence microbiome composition. We asked whether BALOs can predict biodiversity levels in microbiomes from distinct host groups and environments. We demonstrate that genetic signatures of BALOs are commonly found within the 16S rRNA reads from diverse host taxa. In many cases, their presence, abundance, and especially richness are positively correlated with overall microbiome diversity. Our findings suggest that BALOs can act as drivers of microbial alpha-diversity and should therefore be considered candidates for the restoration of microbiomes and the prevention of dysbiosis.
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In:  Geo-Marine Letters .
Publication Date: 2019-07-10
Description: High-resolution bathymetry collected with an autonomous underwater vehicle (AUV) along the flanks of three ridges of the accretionary prism offshore southwestern (SW) Taiwan revealed more than 650 elongated depressions in water depths ranging from 1155 to 1420 m. The depressions are between 12 and 129 m long, 5 to 70 m wide, and up 9 m deep at their center and shallowing downslope to about 1-m depth. Due to their shape in downslope cross section, they are termed comet-shaped depressions (CSD). The CSD occur in patches of more than 100 with densities of 53 to 98 CSD/km2. In addition, seven topographic mounds were mapped and interpreted as pingos, which remotely operate vehicle (ROV) observations and sampling show to be covered with authigenic carbonate. These features overlie areas where multichannel seismic reflection (MCS) profiles show bottom simulating reflectors (BSR) and dipping strata extending from below the BSR to near the seafloor. We consider comet-shaped depression, a new type of pockmark, forms on a sloping seafloor where fluids expulsion occurred. We also suggest that the two types of distinctive geomorphic features are attributed to fluid venting which occurs at different rates, with the mounds developing slowly over time, but the CSD forming in discrete events perhaps associated with large earthquakes.
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In:  Archaeological and Anthropological Sciences, 11 (4). pp. 1359-1371.
Publication Date: 2019-07-08
Description: Using a portable gas analyzer system, the geogenic gas regime below and around an ancient gate to hell at Hierapolis/Phrygia was characterized. The site was first described by Strabo and Plinius as a gate to the underworld. During centuries, it attracted even ancient tourists. In a grotto below the temple of Pluto, CO2 was found to be at deadly concentrations of up to 91%. Astonishingly, these vapors are still emitted in concentrations that nowadays kill insects, birds, and mammals. The concentrations of CO2 escaping from the mouth of the grotto to the outside atmosphere are still in the range of 4–53% CO2 depending on the height above ground level. They reach concentrations during the night that would easily kill even a human being within a minute. These emissions are thought to reflect the Hadean breath and/or the breath of the hellhound Kerberos guarding the entrance to hell. The origin of the geogenic CO2 is the still active seismic structure that crosses the old town of ancient Hierapolis as part of the Babadag fracture zone. Our measurements confirm the presence of geogenic CO2 in concentrations that explain ancient stories of killed bulls, rams, and songbirds during religious ceremonies. They also strongly corroborate that at least in the case of Hierapolis, ancient writers like Strabo or Plinius described a mystic phenomenon very exactly without much exaggeration. Two thousand years ago, only supernatural forces could explain these phenomena from Hadean depths whereas nowadays, modern techniques hint to the well-known phenomenon of geogenic CO2 degassing having mantle components with relatively higher helium and radon concentrations.
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In:  Earth Systems and Environment, 3 (2). pp. 241-253.
Publication Date: 2019-07-15
Description: Dramatic changes from a cold and dry last glacial to a warm and wet Holocene period intensified the Indian summer monsoon (ISM), resulting in vigorous hydrology and increased terrestrial erosion. Here we present seawater neodymium (Nd) data (expressed in εNd) from Andaman Sea sediments to assess past changes in the ISM and the related impact of Irrawaddy–Salween and Sittoung (ISS) river discharge into the Andaman Sea in the northeastern Indian Ocean. Four major isotopic changes were identified: (1) a gradual increase in εNd toward a more radiogenic signature during the Last Glacial Maximum (22–18 ka), suggesting a gradual decrease in the ISS discharge; (2) a relatively stable radiogenic seawater εNd between 17.2 and 8.8 ka, perhaps related to a stable reduced outflow; (3) a rapid transition to less radiogenic εNd signature after 8.8 ka, reflecting a very wet early–mid-Holocene with the highest discharge; and (4) a decrease in εNd signal stability in the mid–late Holocene. Taking into account the contribution of the ISS rivers to the Andaman Sea εNd signature that changes proportionally with the strengthening (less radiogenic εNd) or weakening (more radiogenic εNd) of the ISM, we propose a binary model mixing between the Salween and Irrawaddy rivers to explain the εNd variability in Andaman Sea sediments. We hypothesize that the Irrawaddy river mainly contributed detrital sediment to the northeastern Andaman Sea for the past 24 ka. Our εNd data shed new light on the regional changes in Indo-Asian monsoon systems when compared with the existing Indian and Chinese paleo-proxy records.
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In:  Journal of Coastal Conservation, 23 (3). pp. 571-587.
Publication Date: 2019-07-31
Description: As coastal areas become increasingly vulnerable to climate change, the study of nearshore sediment textures along the littoral cell of the Medjerda delta in the Gulf of Tunis, southern Mediterranean coast can provide valuable information (i) on the origin (continental or marine) of the sediment, (ii) its transport direction, and (iii) constitutes an important tool in the assessment of coastal sensitivity. A total of 120 sediments samples underwent grain size analysis and statistic parameters have been calculated. These allowed the identification of five different Sedimentary Types (ST). Accordingly, using grain size indexes (i.e. Mz, SKI and Ku), Sediment Trend Analysis (STA) modeling tools were applied to define the seasonal sediment transport pathways throughout the nearshore of the Medjerda sedimentary cell. Results show that grain size distribution (GSD) and STA model pathways are determined by cross-shore geomorphology, location of the sediment-cell, seasonal incident wave and local terrestrial supply. The appearance in an atypical seabed location of the finer (Mo = 0.1 mm) and the coarser STs (Mo = 0.8 mm) can be indicative of human influence since the coarser particles are usually retained by dam structures. Moreover, the bimodality and the increased distribution of mud are also related to the seasonal incident wave winnowing of the historic deltaic plain submerged by the relative rise in sea level. The evolution of the sediment pattern towards a greater proportion of very fine grains indicates a deficit of sediment supply, particularly of the coarser grains, and demonstrates the coastal vulnerability of the Gulf of Tunis due to anthropic effects.
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In:  Antonie van Leeuwenhoek International Journal of General and Molecular Microbiology, 112 (8). pp. 1169-1175.
Publication Date: 2019-08-02
Description: The genus Tabrizicola with its type species and strain Tabrizicola aquatica RCRI19T was previously described as a purely chemotrophic genus of Gram-negative, aerobic, non-motile and rod-shaped bacteria. With the present study, we expand the description of the metabolic capabilities of this genus and the T. aquatica type strain to include chlorophyll-dependent phototrophy. Our results confirmed that T. aquatica, does not grow under anaerobic photoautotrophic or photoheterotrophic conditions. However, the presence of the photosynthesis-related genes pufL and pufM could be demonstrated in the genomes of several Tabrizicola strains. Additionally, photosynthetic pigments (bacteriochlorophyll a) were formed under aerobic, heterotrophic and low light conditions in T. aquatica strain RCRI19T. Furthermore, all the genes necessary for a fully operational photosynthetic apparatus and bacteriochlorophyll a are present in the T. aquatica type strain genome. Therefore, we suggest categorising T. aquatica RCRI19T, isolated from freshwater environment of Qurugöl Lake, as an aerobic anoxygenic phototrophic (AAP) bacterium.
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In:  In: Deep Oil Spills: Facts, Fate, and Effects. , ed. by Murawski, S. A., Ainsworth, C. H., Gilbert, S., Hollander, D. J., Paris, C. B., Schlüter, M. and Wetzel, D. L. Springer, Cham, Switzerland, pp. 139-154. ISBN 978-3-030-11604-0
Publication Date: 2019-08-07
Description: Deepwater spills pose a unique challenge for reliable predictions of oil transport and fate, since live oil spewing under very high hydrostatic pressure has characteristics remarkably distinct from oil spilling in shallow water. It is thus important to describe in detail the complex thermodynamic processes occurring in the near-field, meters above the wellhead, and the hydrodynamic processes in the far-field, up to kilometers away. However, these processes are typically modeled separately since they occur at different scales. Here we directly couple two oil prediction applications developed during the Deepwater Horizon blowout operating at different scales: the near-field Texas A&M Oilspill Calculator (TAMOC) and the far-field oil application of the Connectivity Modeling System (oil-CMS). To achieve this coupling, new oil-CMS modules were developed to read TAMOC output, which consists of the description of distinct oil droplet “types,” each of specific size and pseudo-component mixture that enters at a given mass flow rate, time, and position into the far field. These variables are transformed for use in the individual-based framework of CMS, where each droplet type fits into a droplet size distribution (DSD). Here we used 19 pseudo-components representing a large range of hydrocarbon compounds and their respective thermodynamic properties. Simulation results show that the dispersion pathway of the different droplet types varies significantly. Indeed, some droplet types remain suspended in the subsea over months, while others accumulate in the surface layers. In addition, the decay rate of oil pseudo-components significantly alters the dispersion, denoting the importance of more biodegradation and dissolution studies of chemically and naturally dispersed live oil at high pressure. This new modeling tool shows the potential for improved accuracy in predictions of oil partition in the water column and of advancing impact assessment and response during a deepwater spill.
Type: Book chapter , NonPeerReviewed
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In:  In: Deep Oil Spills: Facts, Fate, and Effects. , ed. by Murawski, S. A., Ainsworth, C. H., Gilbert, S., Hollander, D. J., Paris, C. B., Schlüter, M. and Wetzel, D. L. Springer, Cham, Switzerland, pp. 25-42. ISBN 978-3-030-11604-0
Publication Date: 2019-08-07
Description: Petroleum is one of the most complex naturally occurring organic mixtures. The physical and chemical properties of petroleum in a reservoir depend on its molecular composition and the reservoir conditions (temperature, pressure). The composition of petroleum varies greatly, ranging from the simplest gas (methane), condensates, conventional crude oil to heavy oil and oil sands bitumen with complex molecules having molecular weights in excess of 1000 daltons (Da). The distribution of petroleum constituents in a reservoir largely depends on source facies (original organic material buried), age (evolution of organisms), depositional environment (dysoxic versus anoxic), maturity of the source rock (kerogen) at time of expulsion, primary/secondary migration, and in-reservoir alteration such as biodegradation, gas washing, water washing, segregation, and/or mixing from different oil charges. These geochemical aspects define the physical characteristics of a petroleum in the reservoir, including its density and viscosity. When the petroleum is released from the reservoir through an oil exploration accident like in the case of the Deepwater Horizon event, several processes are affecting the physical and chemical properties of the petroleum from the well head into the deep sea. A better understanding of these properties is crucial for the development of near-field oil spill models, oil droplet and gas bubble calculations, and partitioning behavior of oil components in the water. Section 3.1 introduces general aspects of the origin of petroleum, the impact of geochemical processes on the composition of a petroleum, and some molecular compositional and physicochemical background information of the Macondo well oil. Section 3.2 gives an overview over experimental determination of all relevant physicochemical properties of petroleum, especially of petroleum under reservoir conditions. Based on the phase equilibrium modeling using equations of state (EOS), a number of these properties can be predicted which is presented in Sect. 3.3 along with a comparison to experimental data obtained with methods described in Sect. 3.2.
Type: Book chapter , NonPeerReviewed
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In:  Marine Biodiversity, 49 (1). pp. 131-146.
Publication Date: 2019-08-06
Description: Biodiversity is critical for maintaining and stabilizing ecosystem processes. There is a need for high-resolution biodiversity maps that cover large sea areas in order to address ecological questions related to biodiversity-ecosystem functioning relationships and to provide data for marine environmental protection and management decisions. However, traditional sampling-point-wise field work is not suitable for covering extensive areas in high detail. Spatial predictive modeling using biodiversity data from sampling points and georeferenced environmental data layers covering the whole study area is a potential way to create biodiversity maps for large spatial extents. Random forest (RF), generalized additive models (GAM), and boosted regression trees (BRT) were used in this study to produce benthic (macroinvertebrates, macrophytes) biodiversity maps in the northern Baltic Sea. Environmental raster layers (wave exposure, salinity, temperature, etc.) were used as independent variables in the models to predict the spatial distribution of species richness. A validation dataset containing data that was not included in model calibration was used to compare the prediction accuracy of the models. Each model was also evaluated visually to check for possible modeling artifacts that are not revealed by mathematical validation. All three models proved to have high predictive ability. RF and BRT predictions had higher correlations with validation data and lower mean absolute error than those of GAM. Both mathematically and visually, the predictions by RF and BRT were very similar. Depth and seabed sediments were the most influential abiotic variables in predicting the spatial patterns of biodiversity.
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In:  Animal Cognition .
Publication Date: 2019-08-20
Description: The ecological approach to comparative cognition emphasizes that the ecological and social environment are important predictors of cognitive performance. We used this approach to test whether differences in habitat use and social behavior in the facultative Caribbean cleaning goby Elacatinus prochilos predict differences in learning performance in two discriminatory two-choice tasks. This species has two behavioral ecotypes: one that frequently engages in cleaning interactions and inhabits corals in male–female pairs (cleaning gobies) and another that rarely engages in cleaning interactions and inhabits barrel sponges in large groups (sponge-dwellers). We predicted that cleaning gobies would outperform sponge-dwellers in a pattern-cued task, which consisted of identifying the pattern on a plate that consistently provided food, while sponge-dwellers would outperform cleaning gobies in a spatial task, which consisted of identifying the location of the plate. Contrary to our predictions, there was no difference in performance between the two ecotypes. Most of the gobies performed poorly in the pattern-cued task and well in the spatial task. A possible explanation for these results is that the association of a pattern with positive and negative reinforcement may not be a pre-requisite for engaging in cleaning interactions, while spatial skills might be equally required in both ecotypes. Alternatively, the two ecotypes can flexibly adjust to new feeding conditions, which would explain their similar performance in the spatial task. Further research should investigate which aspects of E. prochilos’ social and ecological environment might impose challenges that require spatial cognition and whether individuals can flexibly adjust to new habitats and feeding conditions.
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In:  Environmental Chemistry Letters, 17 (3). pp. 1281-1298.
Publication Date: 2019-08-21
Description: A broad variety of materials of biological origin have been successfully used in recent decades for the removal of pollutants from waters. These biosorbents include natural polymers that play a key role for adsorption. It is therefore critical to understand the physicochemical properties of the chemical groups of these biopolymers. The acid–base properties of biomass are affected by pH, ionic strength and medium composition. Nevertheless, these parameters are not always considered during biosorption studies. According to the literature, less than 3% of biosorption reports include studies on proton binding. Moreover, in 60% of these papers, there is key experimental information missing such as the calibration of the electrodes employed for potentiometric titrations. We consider therefore that there is an important need for reviewing the role of proton binding in biosorption studies. This review outlines the major advances on data interpretation and modelling of proton binding on biosorbents. In addition, we discuss issues concerning the acid–base properties of biosorbents.
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Publication Date: 2019-08-29
Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Mitchell, S. J., Houghton, B. F., Carey, R. J., Manga, M., Fauria, K. E., Jones, M. R., Soule, S. A., Conway, C. E., Wei, Z., & Giachetti, T. Submarine giant pumice: A window into the shallow conduit dynamics of a recent silicic eruption. Bulletin of Volcanology, 81(7), (2019): 42, doi:10.1007/s00445-019-1298-5.
Description: Meter-scale vesicular blocks, termed “giant pumice,” are characteristic primary products of many subaqueous silicic eruptions. The size of giant pumices allows us to describe meter-scale variations in textures and geochemistry with implications for shearing processes, ascent dynamics, and thermal histories within submarine conduits prior to eruption. The submarine eruption of Havre volcano, Kermadec Arc, in 2012, produced at least 0.1 km3 of rhyolitic giant pumice from a single 900-m-deep vent, with blocks up to 10 m in size transported to at least 6 km from source. We sampled and analyzed 29 giant pumices from the 2012 Havre eruption. Geochemical analyses of whole rock and matrix glass show no evidence for geochemical heterogeneities in parental magma; any textural variations can be attributed to crystallization of phenocrysts and microlites, and degassing. Extensive growth of microlites occurred near conduit walls where magma was then mingled with ascending microlite-poor, low viscosity rhyolite. Meter- to micron-scale textural analyses of giant pumices identify diversity throughout an individual block and between the exteriors of individual blocks. We identify evidence for post-disruption vesicle growth during pumice ascent in the water column above the submarine vent. A 2D cumulative strain model with a flared, shallow conduit may explain observed vesicularity contrasts (elongate tube vesicles vs spherical vesicles). Low vesicle number densities in these pumices from this high-intensity silicic eruption demonstrate the effect of hydrostatic pressure above a deep submarine vent in suppressing rapid late-stage bubble nucleation and inhibiting explosive fragmentation in the shallow conduit.
Description: This study was funded primarily through an NSF Ocean grant: OCE-1357443 (SJM, BFH and RJC). MM is supported by NSF EAR 1447559. The μXRT analysis was performed at the Lawrence Berkeley National Lab Advanced Light Source beamline 8.3.2 and the large CT scan by SAS at the University of Texas Austin micro-CT facility. Capillary flow porometry and He-pycnometry were assisted by TG and MRJ at the University of Oregon. Microprobe analysis was conducted at the University of Hawai’i at Mānoa. CEC was supported by post-doctoral research fellowship from the Japan Society for the Promotion of Science (JSPS16788). We would like to thank Kenichiro Tani, Takashi Sano, and Eric Hellebrand for their assistance with geochemical data acquisition, JoAnn Sinton and Wagner Petrographic for thin section preparation, Zachary Langdalen for binary processing of BSE images, Warren M. McKenzie for measuring clast densities, and Dula Parkinson for guidance with the μXRT imaging. We further acknowledge the full scientific team, crew and Jason ROV team (Woods Hole Oceanographic Institute) aboard the R/V Roger Revelle (Scripps Institute of Oceanography) during the MESH expedition in 2015, without whom, this study would not have been possible. Finally, we thank Andrew Harris, Katharine Cashman, Lucia Gurioli and an anonymous reviewer for their insightful and helpful reviews of the manuscript.
Keywords: Giant pumice ; Submarine volcanism ; Banding ; Tube pumice ; Bubble deformation ; Conduit dynamics
Repository Name: Woods Hole Open Access Server
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Nature Publishing Group | Springer
In:  Nature Communications, 10 (Article number: 4025 ).
Publication Date: 2019-09-17
Description: Export of warm and salty waters from the Caribbean to the North Atlantic is an essential component of the Atlantic Meridional Overturning Circulation (AMOC). However, there was also an active AMOC during the Miocene, despite evidence for an open Central American Seaway (CAS) that would have allowed low-salinity Pacific waters to enter the Caribbean. To address this apparent contradiction and to constrain the timing of CAS closure we present the first continuous Nd isotope record of intermediate waters in the Florida Strait over the past 12.5 million years. Our results indicate that there was no direct intermediate water mass export from the Caribbean to the Florida Strait between 11.5 and 9.5 Ma, at the same time as a strengthened AMOC. After 9 Ma a strong AMOC was maintained due to a major step in CAS closure and the consequent cessation of low-salinity Pacific waters entering the Caribbean.
Type: Article , PeerReviewed
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Springer
In:  Climate Dynamics, 53 (1-2). pp. 261-274.
Publication Date: 2019-09-23
Description: A strong warm event occurred in the southeastern tropical Atlantic Ocean off Angola and Namibia in January and February 2016 with sea surface temperature anomalies reaching 3 °C. In contrast to classical Benguela Niño events, the analysis of various direct observations indicates that the warming was not predominantly forced by an equatorial Kelvin wave exciting a coastally trapped wave but instead resulted from a combination of local processes that are related to (1) a weakening of the alongshore, i.e. mainly southerly, winds and (2) enhanced freshwater input through local precipitation and river discharge. Consistent with the weakened winds, we find a reduction in latent heat loss from the ocean and a poleward surface current anomaly. The surface freshening, which is detected in satellite observations of sea surface salinity, caused a very shallow mixed layer and enhanced upper ocean stratification. This is supported by the analysis of the velocity structure of the Angola Current at 11°S, which shows that at the time of the event subsurface velocities were directed northward while surface velocities were directed southward. The shallow layer of warm and fresh surface water was thus advected poleward by the surface current. In addition, a reduction of the local upwelling and the formation of a barrier layer that inhibits the entrainment of cool subsurface waters into the surface mixed layer might have contributed to the warm surface anomaly. The sudden termination of the warm event was accompanied by a re-intensification of southerly winds in March
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Springer
In:  Climate Dynamics, 53 (1-2). pp. 155-172.
Publication Date: 2019-09-23
Description: Common problems in state-of-the-art climate models are a cold sea surface temperature (SST) bias in the equatorial Pacific and the underestimation of the two most important atmospheric feedbacks operating in the El Niño/Southern Oscillation (ENSO): the positive, i.e. amplifying wind-SST feedback and the negative, i.e. damping heat flux-SST feedback. To a large extent, the underestimation of those feedbacks can be explained by the cold equatorial SST bias, which shifts the rising branch of the Pacific Walker Circulation (PWC) too far to the west by up to 30°, resulting in an erroneous convective response during ENSO events. Based on simulations from the Kiel Climate Model (KCM) and the 5th phase of Coupled Model Intercomparison Project (CMIP5), we investigate how well ENSO dynamics are simulated in case of underestimated ENSO atmospheric feedbacks (EAF), with a special focus on ocean–atmosphere coupling over the equatorial Pacific. While models featuring realistic atmospheric feedbacks simulate ENSO dynamics close to observations, models with underestimated EAF exhibit fundamental biases in ENSO dynamics. In models with too weak feedbacks, ENSO is not predominantly wind-driven as observed; instead ENSO is driven significantly by a positive shortwave radiation feedback. Thus, although these models simulate ENSO, which in terms of simple indices is consistent with observations, it originates from very different dynamics. A too weak oceanic forcing on the SST via the positive thermocline, the Ekman and the zonal advection feedback is compensated by weaker atmospheric heat flux damping. The latter is mainly caused by a biased shortwave-SST feedback that erroneously is positive in most climate models. In the most biased models, the shortwave-SST feedback contributes to the SST anomaly growth to a similar degree as the ocean circulation. Our results suggest that a broad continuum of ENSO dynamics can exist in climate models and explain why climate models with less than a half of the observed EAF strength can still depict realistic ENSO amplitude.
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Springer
In:  Climate Dynamics, 52 (3-4). pp. 1983-2003.
Publication Date: 2019-09-23
Description: A long-standing difficulty of climate models is to capture the annual cycle (AC) of eastern equatorial Pacific (EEP) sea surface temperature (SST). In this study, we first examine the EEP SST AC in a set of integrations of the coupled Kiel Climate Model, in which only atmosphere model resolution differs. When employing coarse horizontal and vertical atmospheric resolution, significant biases in the EEP SST AC are observed. These are reflected in an erroneous timing of the cold tongue’s onset and termination as well as in an underestimation of the boreal spring warming amplitude. A large portion of these biases are linked to a wrong simulation of zonal surface winds, which can be traced back to precipitation biases on both sides of the equator and an erroneous low-level atmospheric circulation over land. Part of the SST biases also is related to shortwave radiation biases related to cloud cover biases. Both wind and cloud cover biases are inherent to the atmospheric component, as shown by companion uncoupled atmosphere model integrations forced by observed SSTs. Enhancing atmosphere model resolution, horizontal and vertical, markedly reduces zonal wind and cloud cover biases in coupled as well as uncoupled mode and generally improves simulation of the EEP SST AC. Enhanced atmospheric resolution reduces convection biases and improves simulation of surface winds over land. Analysis of a subset of models from the Coupled Model Intercomparison Project phase 5 (CMIP5) reveals that in these models, very similar mechanisms are at work in driving EEP SST AC biases.
Type: Article , PeerReviewed , info:eu-repo/semantics/article
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Springer
In:  Climate Dynamics, 52 (5-6). pp. 3223-3239.
Publication Date: 2019-09-23
Description: The Earth will exhibit continued global surface warming in response to a sustained increase of atmospheric carbon dioxide (CO2) levels. Massive meltwater input from the Antarctic ice sheet into the Southern Ocean could be one consequence of this warming. Here we investigate the impacts which this meltwater input may have on Earth’s surface climate and ocean circulation in a warming world. To this end a set of ensemble experiments has been conducted with a global climate model forced by increasing atmospheric CO2-concentration and an idealized Antarctic meltwater input to the Southern Ocean with varying amplitude and spatial pattern. As long as the atmospheric CO2-concentration stays moderate, i.e. below approximately twice the preindustrial concentration, and if a strong meltwater forcing of either 0.05 or 0.1 Sv is applied, enhanced Antarctic sea–ice cover and surface air temperature cooling over most parts of the Southern Ocean is observed. When the atmospheric CO2-concentration becomes larger than twice the preindustrial concentration, the meltwater only plays a minor role. The Antarctic meltwater drives significant slowing of the Southern Ocean meridional overturning circulation (MOC). Again, the meltwater influence only is detectable as long as the CO2-forcing is moderate. Much larger MOC changes develop in response to highly elevated atmospheric CO2-levels independent of whether or not a meltwater forcing is applied. The response of the Antarctic circumpolar current (ACC) is nonlinear. Substantial and persistent ACC slowing is simulated when solely the meltwater forcing of 0.1 Sv is applied, which is due to the halt of Weddell Sea deep convection and subsequent collapse of the Southern Ocean MOC. When the increasing atmospheric CO2-concentration additionally drives the model the ACC partly recovers in the long run. The partial recovery is due to strengthening westerly wind stress over the Southern Ocean, which intensifies the Ekman Cell. This study suggests that Southern Hemisphere climate projections for the twenty-first century could benefit from incorporating interactive Antarctic ice sheet.
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Springer
In:  International Journal of Earth Sciences, 108 . pp. 587-620.
Publication Date: 2019-09-23
Description: The nature of the warm climates of the Cretaceous has been enigmatic since the first numerical climate models were run in the late 1970s. Quantitative simulations of the paleoclimate have consistently failed to agree with information from plant and animal fossils and climate sensitive sediments. The ‘cold continental interior paradox’ (first described by DeConto et al. in Barrera E, Johnson C (eds) Evolution of the Cretaceous Ocean/climate system, vol 332. Geological Society of America Special Paper, Boulder, pp 391–406, 1999), has been an enigma, with extensive continental interiors, especially in northeast Asia, modeled as below freezing in spite of plant and other evidence to the contrary. We reconsider the paleoelevations of specific areas, particularly along the northeastern Siberian continental margin, where paleofloras indeed indicate higher temperatures than suggested by current climate models. Evidence for significant masses of ice on land during even the otherwise warmest times of the Cretaceous is solved by reinterpretation of the δ18O record of fossil plankton. The signal interpreted as an increase in ice volume on land is the same as the signal for an increase in the volume of groundwater reservoirs on land. The problem of a warm Arctic, where fossil floras indicate that they never experienced freezing conditions in winter, could not be solved by numerical simulations using higher CO2 equivalent greenhouse gas concentrations. We propose a solution by assuming that paleoelevations were less than today and that there were much more extensive wetlands (lakes, meandering rivers, swamps, bogs) on the continents than previously assumed. Using ~ 8 × CO2 equivalent greenhouse gas concentrations and assuming 50–75% water surfaces providing water vapor as a supplementary greenhouse gas on the continents reduces the meridional temperature gradients. Under these conditions the equatorial to polar region temperature gradients produce conditions compatible with fossil and sedimentological evidence.
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American Association for the Advancement of Science (AAAS)
In:  Science, 363 (6426). pp. 516-521.
Publication Date: 2019-09-23
Description: To provide an observational basis for the Intergovernmental Panel on Climate Change projections of a slowing Atlantic meridional overturning circulation (MOC) in the 21st century, the Overturning in the Subpolar North Atlantic Program (OSNAP) observing system was launched in the summer of 2014. The first 21-month record reveals a highly variable overturning circulation responsible for the majority of the heat and freshwater transport across the OSNAP line. In a departure from the prevailing view that changes in deep water formation in the Labrador Sea dominate MOC variability, these results suggest that the conversion of warm, salty, shallow Atlantic waters into colder, fresher, deep waters that move southward in the Irminger and Iceland basins is largely responsible for overturning and its variability in the subpolar basin.
Type: Article , PeerReviewed , info:eu-repo/semantics/article
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Springer
In:  Estuaries and Coasts .
Publication Date: 2019-09-23
Description: Fluctuations in abundance of dominant species can cause competitive release of resources with consequences on community structure and functioning. In the present study, changes in the intertidal macroinfauna community of an exposed sandy beach were evaluated during two contrasting periods characterized by low and high densities of the yellow clam Amarilladesma mactroides. The increase in clam abundance and biomass was associated with a significant decrease in abundance of the rest of the community. In particular, a decline was observed for the pea crab Austinixa patagoniensis, a commensal species that lives in the burrows of the shrimp Sergio mirim. Our study demonstrates that fluctuations in clam abundance lead to long-term changes in community structure, suggesting the presence of competitive interactions. The environmental stability over the two periods strengthens the hypothesis that the competition between species is crucial for shaping the ecological community. Stable isotope analysis allows discarding trophic competition as mechanism of exclusion. Image maps reveal complementary distribution of species, showing the relevance of the spatial competition, which is mediated by changes in abundance of a third species. Indeed, high densities of A. mactroides reduce the available area for the establishment of the S. mirim burrows, limiting the foraging behavior of its commensal, the pea crab. Such an interaction drives density-dependent exclusion of the pea crab from the intertidal zone following the establishment of the yellow clam population. This study illustrates that spatial competition triggered by the increase of a bed-forming species can have community-wide consequences in exposed sandy beaches
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Springer
In:  In: Remote Sensing of the Asian Seas. , ed. by Barale, V. and Gade, M. Springer, Cham, pp. 123-138. ISBN 978-3-319-94065-6
Publication Date: 2019-09-23
Description: The Laptev and Eastern Siberian shelves are the world’s broadest shallow shelf systems. Large Siberian rivers and coastal erosion of up to meters per summer deliver large volumes of terrestrial matter into the Arctic shelf seas. In this chapter we investigate the applicability of Ocean Colour Remote Sensing during the ice-free summer season in the Siberian Laptev Sea region. We show that the early summer river peak discharge may be traced using remote sensing in years characterized by early sea-ice retreat. In the summer time after the peak discharge, the spreading of the main Lena River plume east and north-east of the Lena River Delta into the shelf system becomes hardly traceable using optical remote sensing methods. Measurements of suspended particulate matter (SPM) and coloured dissolved organic matter (cDOM) are of the same magnitude in the coastal waters of Buor Khaya Bay as in the Lena River. Match-up analyses of in situ chlorophyll-a (Chl-a) show that standard Medium Resolution Imaging Spectrometer (MERIS) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-derived Chl-a is not a valid remote sensing product for the coastal waters and the inner shelf region of the Laptev Sea. All MERIS and MODIS-derived Chl-a products are overestimated by at least a factor of ten, probably due to absorption by the extraordinarily high amount of non-algal particles and cDOM in these coastal and inner-shelf waters. Instead, Ocean Colour remote sensing provides information on wide-spread resuspension over shallows and lateral advection visible in satellite-derived turbidity. Satellite Sea Surface Temperature (SST) data clearly show hydrodynamics and delineate the outflow of the Lena River for hundreds of kilometres out into the shelf seas.
Type: Book chapter , NonPeerReviewed
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Springer
In:  In: Pattern Recognition - GCPR 2018. , ed. by Brox, T., Bruhn, A. and Fritz, M. Lecture Notes in Computer Science, 11269 . Springer, Cham, Switzerland, pp. 391-404. ISBN 978-3-030-12939-2
Publication Date: 2019-09-23
Description: The size of current plankton image datasets renders manual classification virtually infeasible. The training of models for machine classification is complicated by the fact that a large number of classes consist of only a few examples. We employ the recently introduced weight imprinting technique in order to use the available training data to train accurate classifiers in absence of enough examples for some classes. The model architecture used in this work succeeds in the identification of plankton using machine learning with its unique challenges, i.e. a limited number of training examples and a severely skewed class size distribution. Weight imprinting enables a neural network to recognize small classes immediately without re-training. This permits the mining of examples for novel classes.
Type: Book chapter , PeerReviewed
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Springer
In:  Marine Biodiversity .
Publication Date: 2019-10-09
Description: This manuscript reports the first sightings and collection of the swimming crab Cronius ruber (Lamarck, 1818) on the coast of Madeira Island, Portugal. After the recent record in the Canary Islands, this represents a further step northward on this species’ expansion in distribution in the eastern Atlantic. The crab was first spotted during underwater visual census surveys done by scuba diving in July 2018 and was repeatedly observed during the following months, in different locations on the south coast of Madeira. Analysis of temperature data from several geographic locations where C. ruber is present was performed to assess how thermal regimes and ongoing changes may influence this recent distribution shift. Current temperature trends in Madeira suggest that the arrival and establishment of C. ruber to Madeira might have been facilitated this thermophilic species, adding evidence for the ongoing tropicalization of this area. Finally, the current spread of C. ruber in both Canaries and Madeira island systems highlights the need for a long-term monitoring program targeting this and other non-indigenous species (NIS).
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