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norskBlar i tittel Fakultet for naturvitenskap og teknologi
Viser treff 2187-2206 av 4765
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Ion-dispersion and rapid electron fluctuations in the cusp : a case study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008) -
Ionospheric bow waves and perturbations induced by the 21 August 2017 solar eclipse
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-04)During solar eclipses, the Moon's shadow causes a large reduction in atmospheric energy input, including not only the stratosphere but also the thermosphere and ionosphere. The eclipse shadow has a supersonic motion which is theoretically expected to generate atmospheric bow waves, similar to a fast‐moving river boat, with waves starting in the lower atmosphere and propagating into the ionosphere. ... -
Ionospheric Flow Vortex Induced by the Sudden Decrease in the Solar Wind Dynamic Pressure
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-30)Abrupt changes in the solar wind dynamic pressure can greatly affect the Earth's magnetosphere-ionosphere system. We present an ionospheric flow vortex in the morning sector during the sudden decrease in the solar wind dynamic pressure. The flow vortex was clearly observed by both the Hankasalmi radar and the azimuthal scan mode of the European Incoherent Scatter (EISCAT) Svalbard Radar (ESR). The ... -
Ionospheric Response Observed by EISCAT During the 6–8 September 2017 Space Weather Event: Overview
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-03)We present ionospheric plasma conditions observed by the EISCAT radars in Tromsø and on Svalbard, covering 68°–81° geomagnetic latitude, during 6–8 September 2017. This is a period when X2.2 and X9.3 X‐ray flares occurred, two interplanetary coronal mass ejections (ICMEs) arrived at the Earth accompanied by enhancements of MeV‐range energetic particle flux in both the solar wind (SEP event) and inner ... -
Iridium corroles exhibit weak near-infrared phosphorescence but efficiently sensitize singlet oxygen formation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-05)Six-coordinate iridium(III) triarylcorrole derivatives, Ir[T<i>p</i>XPC)]L<sub>2</sub>, where T<i>p</i>XPC = tris(para-X-phenyl)corrole (X = CF<sub>3</sub>, H, Me, and OCH<sub>3</sub>) and L = pyridine (py), trimethylamine (tma), isoquinoline (isoq), 4-dimethylaminopyridine (dmap), and 4-picolinic acid (4pa), have been examined, with a view to identifying axial ligands most conducive to near-infrared ... -
Iridium Corroles Exhibit Weak Near-Infrared Phosphorescence but Efficiently Sensitize Singlet Oxygen Formation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-05)Six-coordinate iridium(III) triarylcorrole derivatives, Ir[T<i>p</i>XPC)]L<sub>2</sub>, where T<i>p</i>XPC = tris(<i>para</i>-X-phenyl)corrole (X = CF<sub>3</sub>, H, Me, and OCH<sub>3</sub>) and L = pyridine (py), trimethylamine (tma), isoquinoline (isoq), 4-dimethylaminopyridine (dmap), and 4-picolinic acid (4pa), have been examined, with a view to identifying axial ligands most conducive to ... -
Iridium(VII)-Corrole Terminal Carbides Should Exist as Stable Compounds
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-14)Scalar-relativistic DFT calculations with multiple exchangecorrelation functionals and large basis sets foreshadow the existence of stable iridium(VII)−corrole terminal carbide derivatives. For the parent compound Ir[Cor](C), OLYP/STO-TZ2P calculations predict a short Ir− C bond distance of 1.69 Å, a moderately domed macrocycle with no indications of ligand noninnocence, a surprisingly low ... -
Iridium-PHOX-mediated alkene hydrogenation: Isomerisation influences the stereochemical outcome
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014-05-27)Recent experimental studies of iridium-phosphinooxazoline-mediated alkene hydrogenation indicated two dihydride species as resting states, with the minor isomer assumed to give rise to the major product enantiomer [Gruber and Pfaltz, Angew. Chem. Int. Ed. 2014, 53, 1896]. B3LYP-D2 calculations confirm the two dihydride intermediates as resting states but show that these species do not give rise to ... -
Iron cycling in Arctic methane seeps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-26)Anoxic marine sediments contribute a significant amount of dissolved iron (Fe<sup>2+</sup>) to the ocean which is crucial for the global carbon cycle. Here, we investigate iron cycling in four Arctic cold seeps where sediments are anoxic and sulfidic due to the high rates of methane-fueled sulfate reduction. We estimated Fe<sup>2+</sup> diffusive fluxes towards the oxic sediment layer to be in the ... -
Iron dependent gene regulation and siderophore systems in Vibrionaceae
(Doctoral thesis; Doktorgradsavhandling, 2017-03-15)Bacteria live in fluctuating environments, which they sense and respond to through gene regulation. Availably of iron is an example of an element fluctuating and that can Bacteria sense.Iron is an essential micronutrient that is scares in several environments, especially in a host. The ferric uptake regulator, Fur, is the major iron level sensing protein and regulator of iron acquisition systems in ... -
Iron isotopes constrain sub-seafloor hydrothermal processes at the Trans-Atlantic Geotraverse (TAG) active sulfide mound
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-29)Sub-seafloor hydrothermal processes along volcanically active plate boundaries are integral to the formation of seafloor massive sulfide deposits and to oceanic iron cycling, yet the nature of their relationship is poorly understood. Here we apply iron isotope analysis to sulfide minerals from the Trans-Atlantic Geotraverse (TAG) mound and underlying stockwork, 26°N Mid-Atlantic Ridge, to trace ... -
IRON-MAN: An Approach to Perform Temporal Motionless Analysis of Video Using CNN in MPSoC
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-20)This paper proposes a novel human-inspired methodology called IRON-MAN (Integrated RatiONal prediction and Motionless ANalysis) for mobile multi-processor systems-on-chips (MPSoCs). The methodology integrates analysis of the previous image frames of the video to represent the analysis of the current frame in order to perform Temporal Motionless Analysis of the Video (TMAV). This is the first work ... -
Iron/Brønsted Acid Catalyzed Asymmetric Hydrogenation: Mechanism and Selectivity-Determining Interactions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-06-03)Hydrogenation catalysts involving abundant base metals such as cobalt or iron are promising alternatives to precious metal systems. Despite rapid progress in this field, base metal catalysts do not yet achieve the activity and selectivity levels of their precious metal counterparts. Rational improvement of base metal complexes is facilitated by detailed knowledge about their mechanisms and ... -
Iron‐Catalyzed Carbenoid Transfer Reactions of Vinyl Sulfoxonium Ylides: An Experimental and Computational Study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-15)A method for the generation of unprecedented vinyl carbenoids from sulfoxonium ylides has been developed and applied in the synthesis of a diverse array of heterocycles such as indolizines, pyrroles, 3‐pyrrolin‐2‐ones, and furans. The reactions proceed by FeBr<sub>2</sub> catalysis under mild reaction conditions with a broad substrate scope. A reaction pathway involving iron carbenoids is proposed ... -
Irregular structures of the F layer at high latitudes during ionospheric heating.
(Journal article; Peer reviewed; Tidsskriftartikkel, 2000)Results on heating the ionospheric F region above Tromsø, Norway are presented. The ionosphere was monitored by satellite tomography and amplitude scintillation methods as well as the EISCAT incoherent scatter radar. No effect of heating was observed in the daytime. In the evening and in the pre-midnight sector, noticeable tilts of the F region were observed during heating periods. The tilts overlapped ... -
Is a net life cycle balance for energy and materials achievable for a zero emission single-family building in Norway?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-01)In this study, the objective is to redesign a previous concept for a single-family Zero greenhouse gas Emission Building (ZEB). The concept is redesigned based on comparing greenhouse gas (GHG) emission loads and compensation from different design solutions applied in Norwegian single-family ZEB pilot buildings and selected sensitivity studies. The objective is to see if a previously developed ZEB ... -
Is there a break in scaling on centennial time scales in Holocene temperature records?
(Conference object; Konferansebidrag, 2017) -
Is there a Climatic Control on Icelandic Volcanism?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-07)The evidence for periods of increased volcanic activity following deglaciation, such as following ice sheet retreat after the Last Glacial Maximum, has been examined in several formerly glaciated areas, including Iceland, Alaska, and the Andean Southern Volcanic Zone. Here we present new evidence supporting the theory that during episodes of cooling in the Holocene, Icelandic volcanic activity ... -
Isdynamikk i tre mindre fjord-trausystemer langs Finnmarkskysten
(Master thesis; Mastergradsoppgave, 2019-07-01)Multistråle batymetriske data og seismiske profiler fra den vestlige kysten av Finnmark er analysert med formålet om å rekonstruere dynamikken til det Fennoskandiske Isdekket gjennom siste glasiale maksimum, og påfølgende deglasiasjon. Fokuset har vært på tre prograderende kiler i forlengelsen av de glasiale trauene Rolvsøy-, Hjelmsøy- og Måsøytrauet. En seismisk stratigrafi er definert med tre ... -
Isocorroles as Homoaromatic NIR-Absorbing Chromophores: A First Quantum Chemical Study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-10)Density functional theory calculations of magnetically induced current densities have revealed high diatropic ring currents in unsubstituted isocorrole consistent with homoaromatic character. An examination of the Kohn-Sham molecular orbitals showed clear evidence of homoconjugative interactions in four occupied π-type molecular orbitals as well as in the LUMO. Remarkably, substituents at the saturated ...
