SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Gustavsson Johan 1974 ) srt2:(2005-2009)"

Sökning: WFRF:(Gustavsson Johan 1974 ) > (2005-2009)

  • Resultat 1-10 av 59
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Althoff, Karin, 1974, et al. (författare)
  • Combined segmentation and tracking of neural stem-cells
  • 2005
  • Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - 1611-3349 .- 0302-9743. ; 3540, s. 282-291
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we analyze neural stem/progenitor cells in an time-lapse image sequence. By using information about the previous positions of the cells, we are able to make a. better selection of possible cells out of a collection of blob-like objects. As a blob detector we use Laplacian of Gaussian (LoG) filters at multiple scales, and the cell contours of the selected cells are segmented using dynamic programming. After the segmentation process the cells are tracked in the sequence using a. combined nearest-neighbor and correlation matching technique. An evaluation of the system show that 95% of the cells were correctly segmented and tracked between consecutive frames.
  •  
2.
  •  
3.
  • Degerman, Johan, 1976, et al. (författare)
  • An automatic system for in vitro cell migration studies
  • 2009
  • Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 233:1, s. 178-191
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper describes a system for in vitro cell migration analysis. Adult neural stem/progenitor cells are studied using time-lapse bright-field microscopy and thereafter stained immunohistochemically to find and distinguish undifferentiated glial progenitor cells and cells having differentiated into type-1 or type-2 astrocytes. The cells are automatically segmented and tracked through the time-lapse sequence. An extension to the Chan-Vese Level Set segmentation algorithm, including two new terms for specialized growing and pruning, made it possible to resolve clustered cells, and reduced the tracking error by 65%. We used a custom-built manual correction module to form a ground truth used as a reference for tracked cells that could be identified from the fluorescence staining. On average, the tracks were correct 95% of the time, using our new segmentation. The tracking, or association of segmented cells, was performed using a 2-state Hidden Markov Model describing the random behaviour of the cells. By re-estimating the motion model to conform with the segmented data we managed to reduce the number of tracking parameters to essentially only one. Upon characterization of the cell migration by the HMM state occupation function, it was found that glial progenitor cells were moving randomly 2/3 of the time, while the type-2 astrocytes showed a directed movement 2/3 of the time. This finding indicates possibilities for cell-type specific identification and cell sorting of live cells based on specific movement patterns in individual cell populations, which would have valuable applications in neurobiological research.
  •  
4.
  • Dumitrescu, Mihail, et al. (författare)
  • 10 Gb/s uncooled dilute nitride optical transmitters operating at 1300 nm
  • 2009
  • Ingår i: 2009 Conference on Optical Fiber Communication, OFC 2009; San Diego, CA; United States; 22 March 2009 through 26 March 2009. - Washington, D.C. : OSA. - 9781557528650
  • Konferensbidrag (refereegranskat)abstract
    • Dilute-nitride lasers with record performances have been used to build uncooled transceivers and failure free 10 Gb/s optical transmission was achieved over 815 m of multimode Corning InfiniCor fiber under the LRM standard.
  •  
5.
  •  
6.
  •  
7.
  • Gustavsson, Johan, 1974, et al. (författare)
  • Mode and polarization control in VCSELs using shallow surface structures
  • 2007
  • Ingår i: IET Optoelectronics. ; 1:5, s. 197-205
  • Tidskriftsartikel (refereegranskat)abstract
    • Monolithic techniques for mode and polarisation control in vertical-cavity surface emitting lasers (VCSELs) using shallow surface structures are summarized and put in the context with other techniques in terms of performance and manufacturability. The method of using circular-symmetric surface structures for mode control and their combination with a sub-wavelength surface grating for simultaneous mode and polarisation control is described in detail, and adherent experimental results for both 850-nm and 1.3-µm oxide-confined VCSELs are presented.
  •  
8.
  • Gustavsson, Johan, 1974, et al. (författare)
  • Optimized active region design for high speed 850 nm VCSELs
  • 2009
  • Ingår i: CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference; Munich; Germany; 14 June 2009 through 19 June 2009. - 9781424440801 ; , s. Art. no. 5192928-
  • Konferensbidrag (refereegranskat)abstract
    • Short wavelength (850 nm) VCSELs operating at speeds of 25 Gb/s and above are needed for future highcapacity, short reach data communication links. The modulation bandwidth is intrinsically limited by thedifferential gain of the QWs used in the active region of the VCSEL. In this work we explore the use of strainedInGaAs/AlGaAs QWs and benchmark the performance against conventional GaAs/AlGaAs QWs.An 8-band k⋅p model [1] was used to calculate the energy band dispersions, using band offsets from modelsolid theory [2]. In all cases, the QW and barrier compositions and QW thickness were chosen for a gain peak at845 nm, enabling emission at 850 nm with a small detuning between the gain peak and the cavity resonance.With increasing In-concentration the QW thickness is reduced and the Al-concentration in the barrier isincreased to maintain the gain peak at 845 nm and the number of QWs is increased to maintain opticalconfinement and enable operation at a low carrier density for high differential gain. It was found that theincorporation of up to 10% In leads to a significant reduction in threshold carrier density and increase indifferential gain. This is due to an increased separation and reduced mixing between the highest heavy-hole andlight-hole valence bands (Fig.1). A further increase of In concentration leads to a less marked improvement.With an optimum active region design (5 x 4 nm In0.10Ga0.90As/Al0.37Ga0.63As QWs) a differential gain twice ashigh as that of a conventional design with 3 x 8 nm GaAs/Al0.30Ga0.70As QWs was predicted (Table 1).The improvement of differential gain was experimentally confirmed by extracting the resonance frequencyand its dependence on current from the modulation response of VCSELs with optimized InGaAs/AlGaAs QWand conventional GaAs/AlGaAs QW active regions. The differential gain was calculated from the correspondingD-factors (Fig.2) [3]. Excellent agreement was obtained between theory and experiments (Table 1).VCSELs with an optimized InGaAs/AlGaAs QW active region have a modulation bandwidth of 20 GHz at25° and 15 GHz at 85°C [4] and have enabled error-free transmission over 50 (100) m multimode fiber up to 32(25) Gb/s at a bias current density as low as 11 kA/cm2 under direct current modulation.
  •  
9.
  •  
10.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 59
Typ av publikation
konferensbidrag (32)
tidskriftsartikel (26)
bokkapitel (1)
Typ av innehåll
refereegranskat (53)
övrigt vetenskapligt/konstnärligt (6)
Författare/redaktör
Gustavsson, Johan, 1 ... (57)
Larsson, Anders, 195 ... (51)
Haglund, Åsa, 1976 (27)
Wei, Yongqiang, 1975 (18)
Sadeghi, Mahdad, 196 ... (17)
Wang, Shu Min, 1963 (16)
visa fler...
Westbergh, Petter, 1 ... (16)
Adolfsson, Göran, 19 ... (9)
Hammar, Mattias (6)
Zhao Ternehäll, Huan ... (6)
Jedrasik, Piotr, 195 ... (6)
Bengtsson, Jörgen, 1 ... (5)
Berggren, Jesper (5)
Larkins, Eric (5)
Zhao, Qing Xiang, 19 ... (4)
Mackenzie, R (4)
Lim, Jun (3)
Melanen, P. (3)
Sipilä, Pekko (3)
Vukusic, Josip, 1972 (3)
Dumitrescu, Mihail (3)
Lim, J.J. (3)
Zhang, Z. (2)
Gustavsson, Tomas, 1 ... (2)
Larsson, A (2)
Althoff, Karin, 1974 (2)
Degerman, Johan, 197 ... (2)
Hammar, M (2)
Berggren, J (2)
Wolf, M. (1)
Wang, S (1)
Ghisoni, Marco (1)
Sköld, Mats, 1977 (1)
Berggren, Jan (1)
Carlsson, C (1)
Amann, M. C. (1)
Eriksson, Peter S, 1 ... (1)
Sunnerud, Henrik, 19 ... (1)
Bachmann, A. (1)
Sundgren, Petrus (1)
Thorlin, Thorleif (1)
Kögel, Benjamin, 197 ... (1)
Kashani-Shirazi, Kav ... (1)
Galt, Sheila, 1956 (1)
Marcks von Würtember ... (1)
Campion, R.P. (1)
Foxon, Tom (1)
Faijerson, Jonas, 19 ... (1)
Put, R V D (1)
Schultz, K (1)
visa färre...
Lärosäte
Chalmers tekniska högskola (59)
Kungliga Tekniska Högskolan (2)
Göteborgs universitet (1)
Språk
Engelska (59)
Forskningsämne (UKÄ/SCB)
Teknik (54)
Naturvetenskap (12)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy