Fakultet for naturvitenskap og teknologi: Nye registreringer

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    • Kinetically-Controlled Ni-Catalyzed Direct Carboxylation of Unactivated Secondary Alkyl Bromides without Chain Walking 

      Davies, Jacob; Lyonnet, Julien R.; Carvalho, Bjørn; Sahoo, Basudev; Day, Craig S.; Juliá-Hernández, Francisco; Duan, Yaya; Álvaro Velasco-Rubio, None; Obst, Marc; Norrby, Per-Ola; Hopmann, Kathrin Helen; Martin, Ruben (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-09)
      Herein, we report the direct carboxylation of unactivated secondary alkyl bromides enabled by the merger of photoredox and nickel catalysis, a previously inaccessible endeavor in the carboxylation arena. Site-selectivity is dictated by a kinetically controlled insertion of CO<sub>2</sub> at the initial C(sp<sup>3</sup> )−Br site by the rapid formation of Ni(I)−alkyl species, thus avoiding undesired ...

    • On the impact of net-zero forcing Q-flux change 

      Eiselt, Kai-Uwe; Graversen, Rune Grand (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-22)
      Numerical climate model simulations suggest that global warming is enhanced or hampered by the spatial pattern of the warming itself. This phenomenon is known as the “pattern effect” and has in recent years become the most promising explanation for the change over time of climate sensitivity in climate models. Under historical global warming, different patterns of surface-temperature change have ...

    • Synthesis of Cryptophanes: Recent Advances 

      Kancherla, Sindhu; Hansen, Jørn Hedløy (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-28)
      This review covers the latest developments in the synthesis of cryptophane host molecules since the publication of the last extensive review by Brotin and Dutasta in 2009. The literature has been categorized according to the synthetic method for generating the cryptophane core and we also emphasize emerging late-stage functionalization approaches. The synthetic strategies towards cryptophanes ...

    • Stochastic modeling of blob-like plasma filaments in the scrape-off layer: Correlated amplitudes and velocities 

      Losada, Juan Manuel; Paikina, Olga; Garcia, Odd Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-19)
      A stochastic model for a superposition of uncorrelated pulses with a random distribution of amplitudes, sizes, and velocities is analyzed. The pulses are assumed to move radially with fixed shape and amplitudes decreasing exponentially in time due to linear damping. The pulse velocities are taken to be time-independent but randomly distributed. The implications of a broad distribution of pulse ...

    • Two decades of increasing functional and phylogenetic richness in a mountaintop flora in central Norway 

      Vanneste, Thomas; Graae, Bente Jessen; Kyrkjeeide, Magni Olsen; Lindmo, Sigrid; Michelsen, Ottar; Naranjo-Orrico, Domenica J.; Ray, Courtenay A.; Vandersteene, Matthias; Verheyen, Kris; De Frenne, Pieter (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-27)
      Questions - Analysing how multiple facets of biodiversity vary across space and time can help to predict the vulnerability of mountaintop floras to future environmental changes. Here we addressed the following questions: (a) Are elevational patterns of mountaintop plant diversity consistent across taxonomy, function and phylogeny? (b) How have the taxonomic, functional and phylogenetic dimensions ...

    • An agent-based modelling framework for performance assessment of search and rescue operations in the Barents Sea 

      Ashrafi, Behrooz; Kim, Gibeom; Naseri, Masoud; Barabady, Javad; Dhar, Sushmit; Heo, Gyunyoung; Baek, Sejin (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-21)
      In recent years, the increase in Arctic offshore activities has raised concerns about the search and rescue (SAR) operations as mitigative measures to ensure the safety of shipping and cruise activities. Performing SAR operations in the remote Arctic offshore environment is exceptionally challenging due to the severe environmental conditions, including low temperatures, high waves, strong winds, ...

    • Glacial erosion and quaternary landscape development of the Eurasian Arctic 

      Patton, Henry Jared; Alexandropoulou, Nikolitsa; Lasabuda, Amando P. E.; Knies, Jochen Manfred; Andreassen, Karin Marie; Winsborrow, Monica Caroline Mackay; Laberg, Jan Sverre; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-09-19)
      Multiple ice age cycles spanning the last three million years have fundamentally transformed the Arctic landscape. The cadence, intensity and pattern of this glacial modification underpin the stability of Arctic geosystems over geologic time scales, including its hydrology, circulation patterns, slope stability, hydrocarbon fluid flow, geochemical/sediment cycling and nutrient supply. The Barents ...

    • Probabilistic impact localization in composites using wavelet scattering transform and multi-output Gaussian process regression 

      Ojha, Shivam; Jangid, Naveen; Shelke, Amit; Habib, Anowarul (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-06-14)
      Data-driven machine-learning models offer considerable promise for acoustic source localization. However, many existing models rely on training data that correlates time-of-flight (TOF) measurements with source locations, yet they struggle to handle the complexities arising from nonlinear wave propagation in materials with varying properties. Furthermore, these models overlook the noise and ...

    • VAMPyR—A high-level Python library for mathematical operations in a multiwavelet representation 

      Bjørgve, Magnar; Tantardini, Christian; Jensen, Stig Rune; Gerez Sazo, Gabriel Adolfo; Wind, Peter; Eikås, Roberto Di Remigio; Dinvay, Evgueni; Frediani, Luca (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-26)
      Wavelets and multiwavelets have lately been adopted in quantum chemistry to overcome challenges presented by the two main families of basis sets: Gaussian atomic orbitals and plane waves. In addition to their numerical advantages (high precision, locality, fast algorithms for operator application, linear scaling with respect to system size, to mention a few), they provide a framework that narrows ...

    • Mechanical Impact of Heterogeneously Distributed H2O on Quartz Deformation 

      Pongrac, Petar; Jeřábek, Petr; Stunitz, Holger; Raimbourg, Hugues; Racek, Martin; Jollands, Michael C.; Gies, Nils; Lueder, Mona; Lexa, Ondrej; Nègre, Lucille (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-07-31)
      In order to identify relations between mechanical behavior, deformation mechanisms, microstructural properties, and H<sub>2</sub>O distribution, Tana‐quartzite samples with added H<sub>2</sub>O ranging from 0 to 0.5 wt.% were deformed by axial shortening at constant displacement rates, at 900°C and 1 GPa, reaching up to ∼30% bulk strain. Samples with lower quantities of added H<sub>2</sub>O (0.1 ...

    • Asymmetric Boracarboxylation of Styrenes Using Carbon Dioxide 

      Pettersen, Martin; Do, Cuong Dat; Gorantla, Sai Manoj N. V. T.; Obst, Marc; Damm, Roman; Putra, Anggi Eka; Gevorgyan, Ashot; Pavlovic, Ljiljana; Hopmann, Kathrin Helen; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-22)
      The boracarboxylation reaction has potential for the production of natural products and drug candidates, but the development of an asymmetric version of this transformation is challenging. We report an enantioselective boracarboxylation of styrenes, enabled by a copper catalyst containing chiral phosphines. Our experimental conditions provide yields between 31–76% and enantiomeric ratios from ...

    • Deep learning models for regional phase detection on seismic stations in Northern Europe and the European Arctic 

      Myklebust, Erik B.; Köhler, Andreas (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-08-23)
      Seismic phase detection and classification using deep learning is so far poorly investigated for regional events since most studies focus on local events and short time windows as the input to the detection models. To evaluate deep learning on regional seismic records, we create a data set of events in Northern Europe and the European Arctic. This data set consists of about 151 000 three component ...

    • Statistical Analysis of Off-Great Circle Radio Wave Propagation in the Polar Cap 

      Cameron, T.G.; Fiori, R.A.D.; Perry, G.W.; Spicher, Andres; Thayaparan, T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-08)
      High latitude ionospheric density structures such as polar cap patches and arcs are capable of deflecting high frequency (HF) radio waves to off‐great circle paths, and are likely detrimental to technologies dependent on HF radio propagation. In this study, nearly 2.5 years of 4.6–14.4 MHz data from a multi‐frequency HF radio link between Qaanaaq, Greenland and Alert, Canada are used to investigate ...

    • A mesoscopic axially swept oblique plane microscope for imaging of freely moving organisms with near-isotropic resolution 

      Prevedel, Robert; Davis, Samuel; Sommernes, Jon-Richard; hambura, sebastian; Riedel, Levin; Gil, Alejandro; Ikmi, Aissam; Ströhl, Florian (Journal article; Tidsskriftartikkel, 2024-08-09)
      Rapid three-dimensional imaging over extended fields of views (FOVs) is crucial to the study of organism-wide systems and biological processes in vivo. Selective-plane illumination microscopy (SPIM) is a powerful method for high spatio-temporal resolution in toto imaging of such biological specimens. However, typical SPIM implementations preclude conventional sample mounting and have anisotropic ...

    • On the degree of varieties of sum of squares 

      Ferguson, Andrew; Ottaviani, Giorgio; Safey el Din, Mohab; Teixeira Turatti, Ettore (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-10)
      We study the problem of how many different sum of squares decompositions a general polynomial <i>f</i> with SOS-rank <i>k</i> admits. We show that there is a link between the variety SOS<sub><i>k</sub></i>(<i>f</i>) of all SOS-decompositions of <i>f</i> and the orthogonal group O(<i>k</i>). We exploit this connection to obtain the dimension of SOS<sub><i>k</sub></i>(<i>f</i>) and show that its degree ...

    • Arctic Freeboard and Snow Depth From Near-Coincident CryoSat-2 and ICESat-2 (CRYO2ICE) Observations: A First Examination of Winter Sea Ice During 2020–2022 

      Hansen, Renee Mie Fredensborg; Skourup, Henriette; Rinne, Eero; Høyland, Knut Vilhelm; Landy, Jack Christopher; Merkouriadi, Ioanna; Forsberg, René (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-04-18)
      In the summer of 2020, ESA changed the orbit of CryoSat-2 to align periodically with NASA's ICESat-2 mission, a campaign known as CRYO2ICE, which allows for near-coincident CryoSat-2 and ICESat-2 observations in space and time over the Arctic until summer 2022, where the CRYO2ICE Antarctic campaign was initiated. This study investigates the Arctic CRYO2ICE radar and laser freeboards acquired by ...

    • The span of singular tuples of a tensor beyond the boundary format 

      Sodomaco, Luca; Teixeira Turatti, Ettore (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-10)
      A singular <i>k</i>-tuple of a tensor T of format (<i>n<sub>1</sub></i>, ..., <i>n</i><sub><i><k></i></sub>) is essentially a complex critical point of the distance function from <i>T</i> constrained to the cone of tensors of format (<i>n</i><sub>1</sub>, ..., <i>n<sub>k</sub></i>) of rank at most one. A generic tensor has finitely many complex singular <i>k</i>-tuples, and their number depends only ...

    • Kulturens effekt på sikkerhetsatferd En kvalitativ studie av polske bygg- og anleggsarbeidere i Norge – forholdet mellom kultur, jobbkrav, ressurser og sikkerhetsatferd 

      Strand Jonsmyr, Ida (Master thesis; Mastergradsoppgave, 2024-06-28)
      Bygg- og anleggsbransjen utgjør en svært risikabel arbeidsplass, noe som gjenspeiler seg i omfanget av arbeidsulykker. Av berørte parter er utenlandske, og spesielt polske arbeidere, overrepresentert på skadestatistikken i forbindelse med de mest alvorlige arbeidsulykkene (Mostue et al., 2022). For å sikre en trygg arbeidsplass for alle aktører anses det som nødvendig å drive kontinuerlig ...

    • Migrasjon - en radikal forandring? En eksplorativ litteraturstudie om samspillet mellom migrasjon, radikalisering og samfunnssikkerhet i Norge 

      Vuckovic, Edin (Master thesis; Mastergradsoppgave, 2024-06-03)
      Studien undersøker hvordan migrasjon påvirker samfunnssikkerheten i Norge med tanke på radikalisering. Problemstillingen belyses gjennom en eksplorativ litteraturstudie, basert på en dokumentanalyse av eksisterende forskning. Studien benytter internasjonalt anerkjente teorier for å analysere sammenhengen mellom migrasjon og radikalisering i norsk kontekst. Funnene viser at migrasjonens komplekse ...

    • Utvikling av en positiv sikkerhetskultur gjennom økt risikoforståelse 

      Haugen, Maria (Master thesis; Mastergradsoppgave, 2024-05-30)
      Denne studien undersøker hvilke utfordringer organisasjoner i tunnelbransjen møter i utviklingen av en positiv sikkerhetskultur. En sektor som har en av de høyeste ulykkesratene i landet (Arbeidstilsynet, 2019). Sikkerhetskultur er identifisert som en viktig faktor i arbeidet mot en tryggere arbeidsplass. Tidligere forskning viser imidlertid at det fortsatt er behov for å utforske måter å optimalisere ...