Viser treff 241-260 av 341

    • Late Quaternary temperature variability described as abrupt transitions on a 1/f noise background 

      Rypdal, Kristoffer; Rypdal, Martin Wibe (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-03-31)
      In order to have a scaling description of the climate system that is not inherently non-stationary, the rapid shifts between stadials and interstadials during the last glaciation (the Dansgaard-Oeschger events) cannot be included in the scaling law. The same is true for the shifts between the glacial and interglacial states in the Quaternary climate. When these events are omitted from a scaling ...
    • Global warming projections derived from an observation-based minimal model 

      Rypdal, Kristoffer (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-29)
      A simple conceptual model for the global mean surface temperature (GMST) response to CO2 emissions is presented and analysed. It consists of linear long-memory models for the GMST anomaly response 1T to radiative forcing and the atmospheric CO2-concentration response 1C to emission rate. The responses are connected by the standard logarithmic relation between CO2 concentration and its radiative ...
    • Paris-toppmøtet og spillet om CO2-kvotene 

      Rypdal, Kristoffer (Chronicle; Kronikk, 2015-11-25)
    • Learning similarities between irregularly sampled short multivariate time series from EHRs 

      Mikalsen, Karl Øyvind; Bianchi, Filippo Maria; Soguero-Ruiz, Cristina; Skrøvseth, Stein Olav; Lindsetmo, Rolv-Ole; Revhaug, Arthur; Jenssen, Robert (Conference object; Konferansebidrag, 2016-12-04)
      A large fraction of the Electronic Health Records consists of clinical multivariate time series. Building models for extracting information from these is important for improving the understanding of diseases, patient care and treatment. Such time series are oftentimes particularly challenging since they are characterized by multiple, possibly dependent variables, length variability and irregular ...
    • COPD in primary lung cancer patients: prevalence and mortality 

      Ytterstad, Elinor; Moe, Per Christian; Hjalmarsen, Audhild (Journal article; Peer reviewed; Tidsskriftartikkel, 2016-03-23)
      Background: Previous studies have relied on international spirometry criteria to diagnose COPD in patients with lung cancer without considering the effect lung cancer might have on spirometric results. The aim of this study was to examine the prevalence of COPD and emphysema at the time of primary lung cancer diagnosis and to examine factors associated with survival. Materials and methods: Medical ...
    • A generalization of weight polynomials to matroids 

      Johnsen, Trygve; Roksvold, Jan Nyquist; Verdure, Hugues (Tidsskriftartikkel; Peer reviewed; Journal article, 2015-11-11)
      Generalizing polynomials previously studied in the context of linear codes, we define weight polynomials and an enumerator for a matroid M. Our main result is that these polynomials are determined by Betti numbers associated with N0-graded minimal free resolutions of the Stanley-Reisner ideals of M and so-called elongations of M. Generalizing Greene’s the- orem from coding theory, we show that ...
    • A generalization of Kung’s theorem 

      Johnsen, Trygve; Shiromoto, Keisuke; Verdure, Hugues (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-01)
      We give a generalization of Kung’s theorem on critical exponents of linear codes over a finite field, in terms of sums of extended weight polynomials of linear codes. For all i=k+1,…,ni=k+1,…,n, we give an upper bound on the smallest integer m such that there exist m codewords whose union of supports has cardinality at least i.
    • Stanley-Reisner resolution of constant weight linear codes 

      Johnsen, Trygve; Verdure, Hugues (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-08)
      Given a constant weight linear code, we investigate its weight hierarchy and the Stanley–Reisner resolution of its associated matroid regarded as a simplicial complex. We also exhibit conditions on the higher weights sufficient to conclude that the code is of constant weight.
    • Betti numbers associated to the facet ideal of a matroid 

      Johnsen, Trygve; Roksvold, Jan Nyquist; Verdure, Hugues (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-06)
      To a matroid M with n edges, we associate the so-called facet ideal F(M)⊂k[x1,…,xn] , generated by monomials corresponding to bases of M. We show that when M is a graph, the Betti numbers related to an ℕ0-graded minimal free resolution of F(M) are determined by the Betti numbers related to the blocks of M. Similarly, we show that the higher weight hierarchy of M is determined by the weight hierarchies ...
    • Stem cell regulation: Implications when differentiated cells regulate symmetric stem cell division 

      Høyem, Marte Rørvik; Måløy, Frode; Jakobsen, Per; Brandsdal, Bjørn Olav (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-05-19)
      We use a mathematical model to show that if symmetric stem cell division is regulated by differentiated cells, then changes in the population dynamics of the differentiated cells can lead to changes in the population dynamics of the stem cells. More precisely, the relative fitness of the stem cells can be affected by modifying the death rate of the differentiated cells. This result is interesting ...
    • Dørene lukkes for klimamålene 

      Rypdal, Kristoffer (Journal article; Tidsskriftartikkel, 2016)
      FNs klimapanel har utarbeidet en rekke prognoser for økningen i global middeltemperatur basert på ulike scenarier for ­ut­vik­lingen av utslipp av drivhusgasser og partikler fra menneskelig aktivitet. Disse prognosene er i hovedsak basert på en lang rekke svært komplekse modeller. De mest komplekse, såkalte jordsystemmodeller, omfatter sirkulasjonen i atmosfære og hav, men også isdynamikk, og kjemiske ...
    • Holdbarhet på klippfisk. Vekst av rødmidd i klippfisk lagret ved forhøyede temperaturer (AP2) 

      Lorentzen, Grete Elisabeth; Johansen, Jørn-Owe; Breiland, Mette Serine Wesmajervi; Dahl, Reidun Wenche; Sandaker, Elin Kristianne; Ytterstad, Elinor (Research report; Forskningsrapport, 2016-02)
      I prosjektet «Holdbarhet på klippfisk» er det foretatt studier for å fastsette holdbarhet på klippfisk basert på vekst av rødmidd. Denne rapporten referer til studier hvor klippfisk er lagret ved forhøyede temperaturer. Rød misfarging skyldes vekst av rødmidd som er en ekstrem halofil bakterie og denne blir naturlig tilført fisken gjennom saltet. Emballert loins av klippfisk og flekket klippfisk ble ...
    • Limits to the quantification of local climate change 

      Chapman, Sandra; Stainforth, David A.; Watkins, Nicholas W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-16)
      Abstract Wedemonstrate how the fundamental timescales of anthropogenic climate change limit the identification of societally relevant aspects of changes in precipitation.Weshow that it is nevertheless possible to extract, solely from observations, some confident quantified assessments of change at certain thresholds and locations. Maps of such changes, for a variety of hydrologically-relevant, ...
    • Computer-aided decision support for melanoma detection applied on melanocytic and non-melanocytic skin lesions: a comparison of two systems based on automatic analysis of dermoscopic images 

      Møllersen, Kajsa; Kirchesch, Herbert M.; Zortea, Maciel; Schopf, Thomas Roger Griesbeck; Hindberg, Kristian; Godtliebsen, Fred (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
      Commercially available clinical decision support systems (CDSSs) for skin cancer have been designed for the detection of melanoma only. Correct use of the systems requires expert knowledge, hampering their utility for nonexperts. Furthermore, there are no systems to detect other common skin cancer types, that is, nonmelanoma skin cancer (NMSC). As early diagnosis of skin cancer is essential, there ...
    • Attribution in the presence of a long-memory climate response 

      Rypdal, Kristoffer (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-18)
      Multiple, linear regression is employed to attribute variability in the global surface temperature to various forcing components and prominent internal climatic modes. The purpose of the study is to assess how sensitive attribution is to long-range memory (LRM) in the model for the temperature response. The model response to a given forcing component is its fingerprint and is different for a zero ...
    • Network analysis of geomagnetic substorms using the SuperMAG database of ground-based magnetometer stations 

      Dods, Joe; Chapman, Sandra; Gjerløv, Jesper (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-26)
      The overall morphology and dynamics of magnetospheric substorms is well established in terms of the observed qualitative auroral features seen in ground-based magnetometers. This paper focuses on the quantitative characterization of substorm dynamics captured by ground-based magnetometer stations. We present the first analysis of substorms using dynamical networks obtained from the full available ...
    • Klimakrisen og økonomisk politikk 

      Rypdal, Kristoffer (Chronicle; Kronikk, 2015-11-14)
    • Long-memory effects in linear response models of Earth's temperature and implications for future global warming 

      Rypdal, Martin Wibe; Rypdal, Kristoffer (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-07-15)
      A linearized energy-balance model for global temperature is formulated, featuring a scale-invariant longrange memory (LRM) response and stochastic forcing representing the influence on the ocean heat reservoir from atmospheric weather systems. The model is parameterized by an effective response strength, the stochastic forcing strength, and the memory exponent. The instrumental global surface ...
    • Dørene lukkes for klimamålene 

      Rypdal, Kristoffer (Chronicle; Kronikk, 2015-11-10)
    • Global warming projections derived from an observation-based minimal model 

      Rypdal, Kristoffer (Journal article; Tidsskriftartikkel, 2015-09-18)
      A simple conceptual model for the global mean surface temperature (GMST) response to CO2 emissions is presented and analysed. It consists of linear long-memory models for the GMST anomaly response ∆T to radiative forcing and atmospheric CO2 - 5 concentration response ∆C to emission rate. The responses are connected by the standard logarithmic relation between CO2 concentration and its radiative ...