Artikler, rapporter og annet (matematikk og statistikk): Nye registreringer
Viser treff 241-260 av 353
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Analysis of free text in electronic health records for identification of cancer patient trajectories
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-07)With an aging patient population and increasing complexity in patient disease trajectories, physicians are often met with complex patient histories from which clinical decisions must be made. Due to the increasing rate of adverse events and hospitals facing financial penalties for readmission, there has never been a greater need to enforce evidence-led medical decision-making using available ... -
Using anchors from free text in electronic health records to diagnose postoperative delirium
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-19)Objectives:<br> Postoperative delirium is a common complication after major surgery among the elderly. Despite its potentially serious consequences, the complication often goes undetected and undiagnosed. In order to provide diagnosis support one could potentially exploit the information hidden in free text documents from electronic health records usin ... -
Comparison of computer systems and ranking criteria for automatic melanoma detection in dermoscopic images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-21)Melanoma is the deadliest form of skin cancer, and early detection is crucial for patient survival. Computer systems can assist in melanoma detection, but are not widespread in clinical practice. In 2016, an open challenge in classification of dermoscopic images of skin lesions was announced. A training set of 900 images with corresponding class labels and semi-automatic/manual segmentation masks ... -
Leakage from medically-certified to self-certified workplace absence among norwegian employees
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-05)There are two different kinds of sickness absence in Norway: self-certified absence (SCA), and medically-certified absence (MCA). In this study of 6437 Norwegian employees, we applied logistic regression models for a dichotomous SCA variable on initially 38 independent vari- ables including age and gender. Our findings showed that employees reporting long-term health issues but no record of MCA ... -
Elemental carbon measurements in European Arctic snow packs
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013-12-26)Black carbon (BC) and other light-absorbing particles deposited on snow and ice are known to perturb the surface radiative balance. There are few published observations of the concentration of these particles in the snow in Scandinavia and the European Arctic. We measured BC concentrations in snow samples collected in this region from 2007 to 2009, and we present the results here. The data set ... -
Dynamic self-organisation of haematopoiesis and (a)symmetric cell division
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-05)A model of haematopoiesis that links self-organisation with symmetric and asymmetric cell division is presented in this paper. It is assumed that all cell divisions are completely random events, and that the daughter cells resulting from symmetric and asymmetric stem cell divisions are, in general, phenotypically identical, and still, the haematopoietic system has the flexibility to self-renew, ... -
Statistics of Regional Surface Temperatures after 1900: Long-Range versus Short-Range Dependence and Significance of Warming Trends
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)This paper studies regional climate variability for the time period 1900–2013 using parsimonious stochastic models. Instrumental data records on 5° × 5°, 2° × 2°, and equal-area grids are examined. A long-range dependent (LRD) stochastic process is used as a simplified description of the multitude of response times in the climate system. Fitting a linear trend to the global mean surface temperature ... -
Spectral characteristics of instrumental and climate model surface temperatures
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-05)The spatiotemporal temperature variability for several gridded instrumental and general circulation climate model data is characterized, contrasting power spectra of local and global temperatures, land and sea temperatures, and temperatures of different regions. There is generally a high degree of agreement between the spectral characteristics of instrumental and climate model data. All but the ... -
Early-warning signals for the onsets of Greenland interstadials and the younger dryas-preboreal transition
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-20)The climate system approaches a tipping point if the prevailing climate state loses stability, making a transition to a different state possible. A result from the theory of randomly driven dynamical systems is that the reduced stability in the vicinity of a tipping point is accompanied by increasing fluctuation levels and longer correlation times (critical slowing down) and can in principle serve ... -
On Data-Independent Properties for Density-Based Dissimilarity Measures in Hybrid Clustering
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-12)Hybrid clustering combines partitional and hierarchical clustering for computational effectiveness and versatility in cluster shape. In such clustering, a dissimilarity measure plays a crucial role in the hierarchical merging. The dissimilarity measure has great impact on the final clustering, and data-independent properties are needed to choose the right dissimilarity measure for the problem ... -
Are there multiple scaling regimes in Holocene temperature records?
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-28)In this article it is discussed how temperature variability on centennial timescales and longer can be described in a simplistic way. By analysing the scaling in late Holocene temperature reconstructions and longer temperature records from Greenland and Antarctic ice cores, we find that the choice of model depends heavily on the data material and timescale one chooses to emphasize. Ignoring data ... -
Comment on "Scaling regimes and linear/nonlinear responses of last millennium climate to volcanic and solar forcing" by S. Lovejoy and C. Varotsos (2016)
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-13)Lovejoy and Varotsos (2016) (L&V) analyse the temperature response to solar, volcanic, and solar plus volcanic forcing in the Zebiak–Cane (ZC) model, and to solar and solar plus volcanic forcing in the Goddard Institute for Space Studies (GISS) E2-R model. By using a simple wavelet filtering technique they conclude that the responses in the ZC model combine subadditively on timescales from 50 to ... -
Late Quaternary temperature variability described as abrupt transitions on a 1/f noise background
(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
(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
(Chronicle; Kronikk, 2015-11-25) -
Learning similarities between irregularly sampled short multivariate time series from EHRs
(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
(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
(Tidsskriftartikkel; Journal article; Peer reviewed, 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
(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
(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.