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  1. Free, publicly-accessible full text available June 1, 2024
  2. Abstract Motivation

    Spectral unmixing methods attempt to determine the concentrations of different fluorophores present at each pixel location in an image by analyzing a set of measured emission spectra. Unmixing algorithms have shown great promise for applications where samples contain many fluorescent labels; however, existing methods perform poorly when confronted with autofluorescence-contaminated images.

    Results

    We propose an unmixing algorithm designed to separate fluorophores with overlapping emission spectra from contamination by autofluorescence and background fluorescence. First, we formally define a generalization of the linear mixing model, called the affine mixture model (AMM), that specifically accounts for background fluorescence. Second, we use the AMM to derive an affine nonnegative matrix factorization method for estimating fluorophore endmember spectra from reference images. Lastly, we propose a semi-blind sparse affine spectral unmixing (SSASU) algorithm that uses knowledge of the estimated endmembers to learn the autofluorescence and background fluorescence spectra on a per-image basis. When unmixing real-world spectral images contaminated by autofluorescence, SSASU greatly improved proportion indeterminacy as compared to existing methods for a given relative reconstruction error.

    Availability and implementation

    The source code used for this paper was written in Julia and is available with the test data at https://github.com/brossetti/ssasu.

     
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  3. Free, publicly-accessible full text available September 1, 2024
  4. A<sc>bstract</sc>

    Measurements of the production of electrons from heavy-flavour hadron decays in pp collisions at$$ \sqrt{s} $$s= 13 TeV at midrapidity with the ALICE detector are presented down to a transverse momentum (pT) of 0.2 GeV/cand up topT= 35 GeV/c, which is the largest momentum range probed for inclusive electron measurements in ALICE. In p-Pb collisions, the production cross section and the nuclear modification factor of electrons from heavy-flavour hadron decays are measured in thepTrange 0.5< pT<26 GeV/cat$$ \sqrt{s_{\textrm{NN}}} $$sNN= 8.16 TeV. The nuclear modification factor is found to be consistent with unity within the statistical and systematic uncertainties. In both collision systems, first measurements of the yields of electrons from heavy-flavour hadron decays in different multiplicity intervals normalised to the multiplicity-integrated yield (self-normalised yield) at midrapidity are reported as a function of the self-normalised charged-particle multiplicity estimated at midrapidity. The self-normalised yields in pp and p-Pb collisions grow faster than linear with the self-normalised multiplicity. A strongpTdependence is observed in pp collisions, where the yield of high-pTelectrons increases faster as a function of multiplicity than the one of low-pTelectrons. The measurement in p-Pb collisions shows nopTdependence within uncertainties. The self-normalised yields in pp and p-Pb collisions are compared with measurements of other heavy-flavour, light-flavour, and strange particles, and with Monte Carlo simulations.

     
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    Free, publicly-accessible full text available August 1, 2024
  5. Free, publicly-accessible full text available August 1, 2024