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  • 1. Aad, G.
    et al.
    Lund-Jensen, Bengt
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Røhne, O
    KTH, School of Engineering Sciences (SCI), Physics.
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zwalinski, L.
    et al.,
    Search for anomaly-mediated supersymmetry breaking with the ATLAS detector based on a disappearing-track signature in pp collisions at root s=7 TeV2012In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 72, no 4, p. 1993-Article in journal (Refereed)
    Abstract [en]

    In models of anomaly-mediated supersymmetry breaking (AMSB), the lightest chargino is predicted to have a lifetime long enough to be detected in collider experiments. This letter explores AMSB scenarios in pp collisions at root s = 7 TeV by attempting to identify decaying charginos which result in tracks that appear to have few associated hits in the outer region of the tracking system. The search was based on data corresponding to an integrated luminosity of 1.02 fb(-1) collected with the ATLAS detector in 2011. The p(T) spectrum of candidate tracks is found to be consistent with the expectation from Standard Model background processes and constraints on the lifetime and the production cross section were obtained. In the minimal AMSB framework with m(3/2) < 32 TeV, m(0) < 1.5 TeV, tan beta = 5 and mu > 0, a chargino having mass below 92 GeV and a lifetime between 0.5 ns and 2 ns is excluded at 95 % confidence level.

  • 2.
    Ahlquist, Mårten S. G.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Marcos-Escartin, Rocio
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Bicarbonate hydrogenation by iron: Effects of solvent and ligand on the mechanism2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 3. Arimoto, Makoto
    et al.
    Asano, Katsuaki
    Ohno, Masanori
    Veres, Peter
    Axelsson, Magnus
    KTH, School of Engineering Sciences (SCI), Physics. Tokyo Metropolitan University, Japan.
    Bissaldi, Elisabetta
    Tachibana, Yutaro
    Kawai, Nobuyuki
    HIGH-ENERGY NON-THERMAL AND THERMAL EMISSION FROM GRB 141207A DETECTED BY FERMI2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 833, no 2, article id 139Article in journal (Refereed)
    Abstract [en]

    A bright long gamma-ray burst GRB 141207A was observed by the Fermi Gamma-ray Space Telescope and detected by both instruments onboard. The observations show that the spectrum in the prompt phase is not well described by the canonical empirical Band function alone, and that an additional power-law component is needed. In the early phase of the prompt emission, a modified blackbody with a hard low-energy photon index (alpha = +0.2 to +0.4) is detected, which suggests a photospheric origin. In a finely time-resolved analysis, the spectra are also well fitted by the modified blackbody combined with a power-law function. We discuss the physical parameters of the photosphere such as the bulk Lorentz factor of the relativistic flow and the radius. We also discuss the physical origin of the extra power-law component observed during the prompt phase in the context of different models such as leptonic and hadronic scenarios in the internal shock regime and synchrotron emission in the external forward shock. In the afterglow phase, the temporal and spectral behaviors of the temporally extended high-energy emission and the fading X-ray emission detected by the X-Ray Telescope on-board Swift are consistent with synchrotron emission in a radiative external forward shock.

  • 4.
    Chen, Guanying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ohulchanskyy, T. Y.
    Liu, S.
    Law, W. -C
    Wu, F.
    Swihart, M. T.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, P. N.
    Core/shell NaGdF 4:Nd 3+/NaGdF 4 nanocrystals with efficient near-infrared to near-infrared downconversion photoluminescence for bioimaging applications2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 4, p. 2969-2977Article in journal (Refereed)
    Abstract [en]

    We have synthesized core/shell NaGdF 4:Nd 3+/NaGdF 4 nanocrystals with an average size of 15 nm and exceptionally high photoluminescence (PL) quantum yield. When excited at 740 nm, the nanocrystals manifest spectrally distinguished, near-infrared to near-infrared (NIR-to-NIR) downconversion PL peaked at ∌900, ∌1050, and ∌1300 nm. The absolute quantum yield of NIR-to-NIR PL reached 40% for core-shell nanoparticles dispersed in hexane. Time-resolved PL measurements revealed that this high quantum yield was achieved through suppression of nonradiative recombination originating from surface states and cross relaxations between dopants. NaGdF 4:Nd 3+/NaGdF 4 nanocrystals, synthesized in organic media, were further converted to be water-dispersible by eliminating the capping ligand of oleic acid. NIR-to-NIR PL bioimaging was demonstrated both in vitro and in vivo through visualization of the NIR-to-NIR PL at ∌900 nm under incoherent lamp light excitation. The fact that both excitation and the PL of these nanocrystals are in the biological window of optical transparency, combined with their high quantum efficiency, spectral sharpness, and photostability, makes these nanocrystals extremely promising as optical biomaging probes.

  • 5.
    Chen, Guanying
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Shen, Jie
    Ohulchanskyy, Tymish Y.
    Patel, Nayan J.
    Kutikov, Artem
    Li, Zhipeng
    Song, Jie
    Pandey, Ravindra K.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    Han, Gang
    (alpha-NaYbF4:Tm3+)/CaF2 Core/Shell Nanoparticles with Efficient Near-Infrared to Near-Infrared Upconversion for High-Contrast Deep Tissue Bioimaging2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 9, p. 8280-8287Article in journal (Refereed)
    Abstract [en]

    We describe the development of novel and biocompatible core/shell (alpha-NaYbF4:Tm3+)/CaF2 nanoparticles that exhibit highly efficient NIRin-NIROut upconversion (UC) for high contrast and deep bioimaging. When excited at similar to 980 nm, these nanoparticles emit photoluminescence (PL) peaked at similar to 800 nm. The quantum yield of this UC PL under low power density excitation (similar to 0.3 W/cm(2)) is 0.6 +/- 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF2 shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).

  • 6. Fuhrmann, L.
    et al.
    Angelakis, E.
    Zensus, J. A.
    Nestoras, I.
    Marchili, N.
    Pavlidou, V.
    Karamanavis, V.
    Ungerechts, H.
    Krichbaum, T. P.
    Larsson, S.
    KTH, School of Engineering Sciences (SCI), Physics.
    Lee, S. S.
    Max-Moerbeck, W.
    Myserlis, I.
    Pearson, T. J.
    Readhead, A. C. S.
    Richards, J. L.
    Sievers, A.
    Sohn, B. W.
    The F-GAMMA programme: multi-frequency study of active galactic nuclei in the Fermi era Programme description and the first 2.5 years of monitoring2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 596, article id A45Article in journal (Refereed)
    Abstract [en]

    Context. To fully exploit the scientific potential of the Fermi mission for the physics of active galactic nuclei (AGN), we initiated the F-GAMMA programme. Between 2007 and 2015 the F-GAMMA was the prime provider of complementary multi-frequency monitoring in the radio regime. Aims. We quantify the radio variability of gamma-ray blazars. We investigate its dependence on source class and examine whether the radio variability is related to the gamma-ray loudness. Finally, we assess the validity of a putative correlation between the two bands. Methods. The F-GAMMA performed monthly monitoring of a sample of about 60 sources at up to twelve radio frequencies between 2.64 and 228.39 GHz. We perform a time series analysis on the first 2.5-yr data set to obtain variability parameters. A maximum likelihood analysis is used to assess the significance of a correlation between radio and gamma-ray fluxes. Results. We present light curves and spectra (coherent within ten days) obtained with the Effelsberg 100 m and IRAM 30 m telescopes. All sources are variable across all frequency bands with amplitudes increasing with frequency up to rest frame frequencies of around 60-80 GHz as expected by shock-in-jet models. Compared to flat-spectrum radio quasars (FSRQs), BL Lacertae objects (BL Lacs) show systematically lower variability amplitudes, brightness temperatures, and Doppler factors at lower frequencies, while the difference vanishes towards higher ones. The time scales appear similar for the two classes. The distribution of spectral indices appears flatter or more inverted at higher frequencies for BL Lacs. Evolving synchrotron self-absorbed components can naturally account for the observed spectral variability. We find that the Fermi-detected sources show larger variability amplitudes, brightness temperatures, and Doppler factors than non-detected ones. Flux densities at 86.2 and 142.3 GHz correlate with 1 GeV fluxes at a significance level better than 3 sigma, implying that gamma rays are produced very close to the mm-band emission region.

  • 7.
    Gasser, T. Christian
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Gallinetti, Sara
    Xing, Xiao
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Forsell, Caroline
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Swedenborg, Jesper
    Roy, Joy
    Spatial orientation of collagen fibers in the abdominal aortic aneurysm's wall and its relation to wall mechanics2012In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 8, no 8, p. 3091-3103Article in journal (Refereed)
    Abstract [en]

    Collagen is the most abundant protein in mammals and provides the abdominal aortic aneurysm (AAA) wall with mechanical strength, stiffness and toughness. Specifically, the spatial orientation of collagen fibers in the wall has a major impact on its mechanical properties. Apart from valuable microhistological information, this data can be integrated by histomechanical constitutive models thought to improve biomechanical simulations, i.e. to improve the biomechanical rupture risk assessment of AAAs. Tissue samples (n = 24) from the AAA wall were harvested during elective AAA repair, fixated, embedded, sectioned and investigated by polarized light microscopy. The birefringent properties of collagen were reinforced by picrosirius red staining and the three-dimensional collagen fiber orientations were identified with a universal rotary stage. Two constitutive models for collagen fibers were used to integrate the identified structural information in a macroscopic AAA wall model. The collagen fiber orientation in the AM wall was widely dispersed and could be captured by a Bingham distribution function (kappa(1) = 11.6, kappa(2) = 9.7). The dispersion was much larger in the tangential plane than in the cross-sectional plane, and no significant difference between the medial and adventitial layers could be identified. The layered directional organization of collagen in normal aortas was not evident in the AAA. The collagen organization identified, combined with constitutive descriptions of collagen fibers that depend on its orientation, explain the anisotropic (orthotropic) mechanical properties of the AAA wall. The mechanical properties of collagen fibers depend largely on their undulation, which is an important structural parameter that requires further experimental investigation.

  • 8.
    Jiang, Haowei
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Pan, F.
    Zhao, Y. M.
    Arima, A.
    Number of spin-I states for three identical particles in a single-j shell2013In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 87, no 3, p. 034313-Article in journal (Refereed)
    Abstract [en]

    In this paper we derive the analytical formulas of the number of spin-I states (denoted as D-I) for three identical particles, in a unified form for both fermions and bosons. This is done by using (n) over bar virtual bosons with spin 3/2, where (n) over bar equals 2j - 2 if one studies fermions in a single-j shell or 2l if one studies bosons with spin l. We first obtain a reduction rule from U(4) to O(3) for such virtual bosons and thereby derive the formulas of D-I. The formulas thus obtained are proved to be consistent with previous empirical formulas.

  • 9.
    Jyothishkumar, V
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx). KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Semlitsch, Bernhard
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx). KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Fuchs, Laszlo
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx). KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Numerical Flow Analysis in a Centrifugal Compressor near Surge Condition2013In: 43rd AIAA Fluid Dynamics Conference and Exhibit, 2013 / [ed] AIAA, AIAA , 2013Conference paper (Refereed)
    Abstract [en]

    This numerical study presents data relevant to the flow characteristics inside of a centrifugal compressor, at design and near-surge conditions. The main objectives were to characterize the flow structures and the associated instabilities near the stall point (prior to surge) and to contrast the obtained results against data acquired for a design operation condition. Generally, the operational range of compressors is limited at low mass flow rates by development of instabilities, e.g. stall and rotating stall. Such conditions lead to breakdown of the operability of the compressor, with flow reversal in the wheel passage. This results in large mass flow variations and pressure fluctuations within the compressor, lowering the compressor efficiency and pressure ratio. Large vibratory stresses are induced in the blade under such off-design operating conditions, affecting the blade life duration. Compressor stall and rotating stall are frequently regarded as “precursors” to the more damaging surge instability.  The flow fields under design and off-design operating conditions are calculated using the Large Eddy Simulation (LES) approach.  The complete geometry (360 degree) of the compressor is considered during analysis. It includes the ported shroud, the compressor wheel, the vaneless diffuser, the volute, and the exit pipe. The computationally expensive transient sliding mesh technique is used in order to capture the interaction between the wheel, the flow, and the stationary components of the compressor. The LES data are validated against available experimental measurements obtained under the same operating conditions (i.e. at design and off-design). The calculated frequency spectra when the compressor operated near-by the surge line indicated the presence of the rotating stall.

  • 10. Karlsson, Charlie
    et al.
    Gråsjö, Urban
    KTH, School of Industrial Engineering and Management (ITM), Centres, Centre of Excellence for Science and Innovation Studies, CESIS. University West, Sweden .
    Entrepreneurial knowledge, technology and the transformation of regions: An introduction2013In: Entrepreneurial Knowledge Technology and the Transformation of Regions, Taylor & Francis, 2013, p. 1-18Chapter in book (Refereed)
  • 11.
    Kateb, Movaffaq
    et al.
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Hajihoseini, Hamidreza
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Ingvarsson, Snorri
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Comparison of magnetic and structural properties of permalloy Ni80Fe20 grown by dc and high power impulse magnetron sputtering2018In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 28, article id 285005Article in journal (Refereed)
    Abstract [en]

    We study the microstructure and magnetic properties of Ni80Fe20 thin films grown by high power impulse magnetron sputtering (HiPIMS), and compare with films grown by dc magnetron sputtering (dcMS). The films were grown under a tilt angle of 35 degrees to identical thickness of 37 nm using both techniques, at different pressure (0.13-0.73 Pa) and substrate temperature (room temperature and 100 degrees C). All of our films display effective in-plane uniaxial anisotropy with square easy axis and linear hard axis magnetization traces. X-ray diffraction reveals that there is very little change in grain size within the pressure and temperature ranges explored. However, variations in film density, obtained by x-ray reflectivity measurements, with pressure have a significant effect on magnetic properties such as anisotropy field (H-k) and coercivity (H-c). Depositions where adatom energy is high produce dense films, while low adatom energy results in void-rich films with higher H-k and H-c. The latter applies to our dcMS deposited films at room temperature and high pressure. However, the HiPIMS deposition method gives higher adatom energy than the dcMS and results in dense films with low H-k and H-c. The surface roughness is found to increase with increased pressure, in all cases, however it showed negligible contribution to the increase in H-k, and H-c.

  • 12.
    Kevrekidis, P. G.
    et al.
    Univ Massachusetts, Dept Math & Stat, Amherst, MA 01003 USA..
    Wang, Wenlong
    KTH, School of Engineering Sciences (SCI), Physics.
    Carretero-Gonzalez, R.
    San Diego State Univ, Nonlinear Dynam Syst Grp, Computat Sci Res Ctr, San Diego, CA 92182 USA.;San Diego State Univ, Dept Math & Stat, San Diego, CA 92182 USA..
    Frantzeskakis, D. J.
    Univ Athens, Dept Phys, Athens 15784, Greece..
    Adiabatic invariant analysis of dark and dark-bright soliton stripes in two-dimensional Bose-Einstein condensates2018In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 97, no 6, article id 063604Article in journal (Refereed)
    Abstract [en]

    In the present work, we develop an adiabatic invariant approach for the evolution of quasi-one-dimensional (stripe) solitons embedded in a two-dimensional Bose-Einstein condensate. The results of the theory are obtained both for the one-component case of dark soliton stripes, as well as for the considerably more involved case of the two-component dark-bright (alias "filled dark") soliton stripes. In both cases, analytical predictions regarding the stability and dynamics of these structures are obtained. One of our main findings is the determination of the instability modes of the waves as a function of the parameters of the system (such as the trap strength and the chemical potential). Our analytical predictions are favorably compared with results of direct numerical simulations.

  • 13.
    Klintström, Eva
    et al.
    Linköping Univ, Dept Med & Hlth Sci, Campus US, S-58185 Linköping, Sweden.;Linkoping Univ, Ctr Med Image Sci & Visualizat CMIV, Campus US, S-58185 Linkoping, Sweden..
    Klintström, Benjamin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Pahr, Dieter
    Vienna Univ Technol, Inst Lightweight Design & Struct Biomech, Vienna, Austria..
    Brismar, Torkel B.
    Karolinska Univ Hosp, Karolinska Inst, Dept Clin Sci Intervent & Technol, Stockholm, Sweden.;Karolinska Univ Hosp, Dept Radiol, Stockholm, Sweden..
    Smedby, Örjan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Medical Imaging. Linköping Univ, Dept Med & Hlth Sci, Linköping, Sweden..
    Moreno, Rodrigo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Medical Imaging.
    Direct estimation of human trabecular bone stiffness using cone beam computed tomography2018In: Oral surgery, oral medicine, oral pathology and oral radiology, ISSN 2212-4403, E-ISSN 2212-4411, Vol. 126, no 1, p. 72-82Article in journal (Refereed)
    Abstract [en]

    Objectives. The aim of this study was to evaluate the possibility of estimating the biomechanical properties of trabecular bone through finite element simulations by using dental cone beam computed tomography data. Study Design. Fourteen human radius specimens were scanned in 3 cone beam computed tomography devices: 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan), NewTom 5 G (QR Verona, Verona, Italy), and Verity (Planmed, Helsinki, Finland). The imaging data were segmented by using 2 different methods. Stiffness (Young modulus), shear moduli, and the size and shape of the stiffness tensor were studied. Corresponding evaluations by using micro-CT were regarded as the reference standard. Results. The 3-D Accuitomo 80 (J. Morita MFG., Kyoto, Japan) showed good performance in estimating stiffness and shear moduli but was sensitive to the choice of segmentation method. Newtom 5 G (QR Verona, Verona, Italy) and Verity (Planmed, Helsinki, Finland) yielded good correlations, but they were not as strong as Accuitomo 80 U. Morita MFG., Kyoto, Japan). The cone beam computed tomography devices overestimated both stiffness and shear compared with the micro-CT estimations. Conclusions. Finite element-based calculations of biomechanics from cone beam computed tomography data are feasible, with strong correlations for the Accuitomo 80 scanner a. Morita MFG., Kyoto, Japan) combined with an appropriate segmentation method. Such measurements might be useful for predicting implant survival by in vivo estimations of bone properties.

  • 14.
    Levamäki, Henrik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Tian, Liyun
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Kokko, Kalevi
    Univ Turku, Dept Phys & Astron, Turku 20014, Finland.;Turku Univ, Ctr Mat & Surfaces MatSurf, Turku, Finland..
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Hungarian Acad Sci, Inst Solid State Phys & Opt, Wigner Res Ctr Phys, POB 49, H-1525 Budapest, Hungary.;Uppsala Univ, Div Mat Theory, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden..
    Gradient-level and nonlocal density functional descriptions of Cu-Au intermetallic compounds2018In: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 91, no 6, article id 128Article in journal (Refereed)
    Abstract [en]

    We use three gradient level and two nonlocal density functional approximations to study the thermodynamic properties of Cu-Au compounds. It is found that a well-designed gradient level approximation (quasi non-uniform approximation, QNA) reproduces the experimental equilibrium volumes and the formation energies of L12 and L10 phases. On the other hand, QNA predicts a non-existent beta(2) phase, which can be remedied only when employing the nonlocal hybrid-level Heyd-Scuseria-Ernzerhof (HSE06) or Perdew-Burke-Ernzerhof (PBE0) approximations. Gradient-level approximations lead to similar electronic structures for the Cu-Au compounds whereas hybrids shift the d-band towards negative energies and account for the complex d-d hybridization more accurately.

  • 15.
    Li, Liang
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Wu, Xue-Feng
    Huang, Yong-Feng
    Wang, Xiang-Gao
    Tang, Qing-Wen
    Liang, Yun-Feng
    Zhang, Bin-Bin
    Wang, Yu
    Geng, Jin-Jun
    Liang, En-Wei
    Wei, Jian-Yan
    Zhang, Bing
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    A CORRELATED STUDY OF OPTICAL AND X-RAY AFTERGLOWS OF GRBs2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 805, no 1, article id 13Article in journal (Refereed)
    Abstract [en]

    We study an extensive sample of 87 gamma-ray bursts (GRBs) for which there are well-sampled and simultaneous optical and X-ray light curves. We extract the cleanest possible signal of the afterglow component. and compare the temporal behaviors of the X-ray light. curve, observed by Swift XRT, and optical data, observed by UVOT and ground-based telescopes for each individual burst. Overall we find that 62% of the GRBs. are consistent with the standard afterglow model. When more advanced modeling is invoked, up to 91% of the bursts in our sample may be consistent with the external-shock model. A large fraction of these bursts are consistent with occurring in a constant interstellar density medium (61%) while only 39% of them occur in a wind-like medium. Only nine cases have afterglow light curves that exactly match the standard fireball model prediction, having a single power-law decay in both energy bands that are observed during their entire duration. In particular, for the bursts with chromatic behavior, additional model assumptions must be made over limited segments of the light curves in order for these bursts to fully agree with the external-shock model. Interestingly, for 54% of the X-ray and 40% of the optical band observations, the end of the shallow decay (t(similar to-0.5)) period coincides with the jet-break (t(similar to-p)) time, causing an abrupt change in decay slope. The fraction of the burst that is consistent with the external-shock model is independent of the observational epochs in the rest frame of GRBs. Moreover, no cases can be explained by the cooling frequency crossing the X-ray or optical band.

  • 16.
    Liu, Xuejin
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Persson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Bornefalk, Hans
    KTH, School of Engineering Sciences (SCI), Physics.
    Karlsson, Staffan
    KTH, School of Engineering Sciences (SCI), Physics.
    Xu, Cheng
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Huber, Ben
    KTH, School of Engineering Sciences (SCI), Physics.
    Spectral response model for a multibin photon-counting spectral computed tomography detector and its applications (vol 2, 033502, 2015)2016In: Journal of Medical Imaging, ISSN 2329-4302, E-ISSN 2329-4310, Vol. 3, no 4, article id 049801Article in journal (Refereed)
  • 17.
    Lopez-Cortes, Daniel
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Tarasenko, O.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    All-fiber Kerr cell2012In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, no 15, p. 3288-3290Article in journal (Refereed)
    Abstract [en]

    An all-fiber nanosecond Kerr light gate is described that was constructed using microstructured fibers. The switching voltage for a 20 cm long device is as low as Vp ∌ 85 V at a 1.06 Όm wavelength. The device is fully spliced. The active element is a three-hole fiber provided with internal electrodes in the side-holes and a liquid core of nitrobenzene, which is fully enclosed. This work allows the exploiting of electrically driven liquid-core fibers and demonstrated the removal of the major limitations of Kerr cells in the past, allowing for integration, safe use, and relatively low switching voltage.

  • 18.
    Ning, Zhijun
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, He
    Organic dyes for dye-sensitized solar cells2012In: Molecular Design and Applications of Photofunctional Polymers and Materials, Royal Society of Chemistry, 2012, p. 373-398Chapter in book (Refereed)
  • 19. Vergote, K.
    et al.
    Lee, J. S.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Claeys, C. C.
    Vandepitte, D.
    Desmet, W.
    On the potential of the wave based method for the efficient optimisation of local vibration control treatments for structural components2012In: International Conference on Noise and Vibration Engineering 2012, ISMA 2012, including USD 2012: International Conference on Uncertainty in Structure Dynamics, Katholieke Universiteit Leuven , 2012, Vol. 3, p. 1985-2002Conference paper (Refereed)
    Abstract [en]

    Local vibration absorbers, such as tuned vibration absorbers or local active control systems, can be used to reduce the response of structural components. The optimisation of the position, the number and the properties of these absorbers, is however a problem of many unknowns. This paper studies the use of an efficient simulation technique, namely the wave based method (WBM), in order to obtain these optimal parameters. In contrast to the finite element method (FEM), where the problem is divided into a large number of small elements in which the field variable is described using simple polynomial shape functions, the WBM divides the problem into a small number of domains in which exact solutions of the governing equation are used as basis functions. This approach not only leads to a numerical efficient technique for the simulation of a system response, it also has inherent advantages over the FEM in an optimisation context. This paper studies the advantages of the WBM in a gradient based optimisation scheme and applies the proposed method for the optimisation of local resonators in order to reduce the vibrational response of a simple plate.

  • 20.
    Wang, Lin
    et al.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Markdahl, Johan
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Hu, Xiaoming
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Computer Science and Communication (CSC), Centres, Centre for Autonomous Systems, CAS.
    Wang, Xiaofan
    Position and attitude tracking for a formation of three agents2012In: Chinese Control Conference, CCC, 2012, p. 6406-6410Conference paper (Refereed)
    Abstract [en]

    In this paper we consider a trajectory tracking control problem for a multi-agent formation consisting of three agents. The agents provide a high level representation of three manipulators that have grasped a rigid object. More precisely, the agents' positions represent the end-effectors' grasp points. The agents are modelled by single integrators, and are designed to move the object such that it is located at a particular position with a particular attitude in a particular time, i.e. position and attitude tracking. The object rigidity is modelled by requiring that the agents should remain at constant relative distances from each other, reducing their three degrees of freedom each to a total of six translational and rotational degrees of freedom for the whole formation. The formation of agents is shown to be equivalent to a rigid body. The position tracking problem is solved using a standard technique whereas the attitude tracking problem is solved by adopting and adapting a recently developed approach.

  • 21.
    Yuan, Chunze
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Chen, Guanying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. University of Buffalo, United States; Harbin Institute of Technology, China .
    Li, Lin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Damasco, Jossana A.
    Ning, Zhijun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Xing, Hui
    Zhang, Tianmu
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zeng, Hao
    Cartwright, Alexander N.
    Prasad, Paras N.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Simultaneous Multiple Wavelength Upconversion in a Core-Shell Nanoparticle for Enhanced Near Infrared Light Harvesting in a Dye-Sensitized Solar Cell2014In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 6, no 20, p. 18018-18025Article in journal (Refereed)
    Abstract [en]

    The efficiency of most photovoltaic devices is severely limited by near-infrared (NIR) transmission losses. To alleviate this limitation, a new type of colloidal upconversion nanoparticles (UCNPs), hexagonal core-shell-structured beta-NaYbF4:Er3+(2%)/NaYF4:Nd3+(30%), is developed and explored in this work as an NIR energy relay material for dye-sensitized solar cells (DSSCs). These UCNPs are able to harvest light energy in multiple NIR regions, and subsequently convert the absorbed energy into visible light where the DSSCs strongly absorb. The NIR-insensitive DSSCs show compelling photocurrent increases through binary upconversion under NIR light illumination either at 785 or 980 nm, substantiating efficient energy relay by these UCNPs. The overall conversion efficiency of the DSSCs was improved with the introduction of UCNPs under simulated AM 1.5 solar irradiation.

  • 22.
    Yuan, Chunze
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Chen, Guanying
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Prasad, Paras N.
    Ohulchanskyy, Tymish Y.
    Ning, Zhijun
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Use of colloidal upconversion nanocrystals for energy relay solar cell light harvesting in the near-infrared region2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 33, p. 16709-16713Article in journal (Refereed)
    Abstract [en]

    Colloidal upconversion (UC) nanocrystals were explored as energy relay materials for dye-sensitized solar cells for the first time. The utilization of colloidal UC nanocrystals was found to significantly enhance the upconversion efficiency and improve the photocurrent of the cells for low infrared irradiation intensity. In addition, it was found that UC nanocrystals of small size favor infiltration into a TiO2 film and bring higher relay efficiency. Finally, we found that UC nanocrystals can serve as a scattering material to increase the light absorption capability of the cells and increase the overall photocurrent of the cells under simulated sunlight irradiation.

  • 23. Zhang, L.
    et al.
    Schwertfager, N.
    Cheiwchanchamnangij, T.
    Lin, X.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Glans-Suzuki, P. -A
    Piper, L. F. J.
    Limpijumnong, S.
    Luo, Yi
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhu, J. F.
    Lambrecht, W. R. L.
    Guo, J. -H
    Electronic band structure of graphene from resonant soft x-ray spectroscopy: The role of core-hole effects2012In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 86, no 24, p. 245430-Article in journal (Refereed)
    Abstract [en]

    The electronic structure and band dispersion of graphene on SiO2 have been studied by x-ray-absorption spectroscopy (XAS), x-ray-emission spectroscopy (XES), and resonant inelastic x-ray scattering (RIXS). Using first-principles calculations, it is found that the core-hole effect is dramatic in XAS while it has negligible consequences in XES. Strong dispersive features, due to the conservation of crystal momentum, are observed in RIXS spectra. Simulated RIXS spectra based on the Kramers-Heisenberg theory agree well with the experimental results, provided a shift between RIXS and XAS due to the absence or presence of the core hole is taken into account.

1 - 23 of 23
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