| 1. |
- Graslund, S, et al.
(author)
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Protein production and purification
- 2008
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In: Nature methods. - : Springer Science and Business Media LLC. - 1548-7105 .- 1548-7091. ; 5:2, s. 135-146
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Journal article (peer-reviewed)
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| 2. |
- Alabarta, K., et al.
(author)
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Failed-transition outbursts in black hole low-mass X-ray binaries
- 2021
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 507:4, s. 5507-5522
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Journal article (peer-reviewed)abstract
- Black hole low-mass X-ray binaries (BH LMXBs) evolve in a similar way during outburst. Based on the X-ray spectrum and variability, this evolution can be divided into three canonical states: low/hard, intermediate, and high/soft state. BH LMXBs evolve from the low/hard to the high/soft state through the intermediate state in some outbursts (here called 'full outbursts'). However, in other cases, BH LMXBs undergo outbursts in which the source never reaches the high/soft state, here called 'failed-transition outbursts' (FT outbursts). From a sample of 56 BH LMXBs undergoing 128 outbursts, we find that 36 percent of these BH LMXBs experienced at least one FT outburst, and that FT outbursts represent similar to 33 percent of the outbursts of the sample, showing that these are common events. We compare all the available X-ray data of full and FT outbursts of BH LMXBs from RXTE/PCA, Swift/BAT, and MAXI, and find that FT and full outbursts cannot be distinguished from their X-ray light curves, hardness-intensity diagrams, or X-ray variability during the initial 10-60 d after the outburst onset. This suggests that both types of outbursts are driven by the same physical process. We also compare the optical and infrared (O/IR) data of FT and full outbursts of GX 339-4. We found that this system is generally brighter in O/IR bands before an FT outburst, suggesting that the O/IR flux points to the physical process that later leads to a full or an FT outburst. We discuss our results in the context of models that describe the onset and evolution of outbursts in accreting X-ray binaries.
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| 3. |
- Vincentelli, Federico M., et al.
(author)
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A shared accretion instability for black holes and neutron stars
- 2023
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 615:7950, s. 45-49
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Journal article (peer-reviewed)abstract
- Accretion disks around compact objects are expected to enter an unstable phase at high luminosity1. One instability may occur when the radiation pressure generated by accretion modifies the disk viscosity, resulting in the cyclic depletion and refilling of the inner disk on short timescales2. Such a scenario, however, has only been quantitatively verified for a single stellar-mass black hole3-5. Although there are hints of these cycles in a few isolated cases6-10, their apparent absence in the variable emission of most bright accreting neutron stars and black holes has been a continuing puzzle11. Here we report the presence of the same multiwavelength instability around an accreting neutron star. Moreover, we show that the variability across the electromagnetic spectrum-from radio to X-ray-of both black holes and neutron stars at high accretion rates can be explained consistently if the accretion disks are unstable, producing relativistic ejections during transitions that deplete or refill the inner disk. Such a new association allows us to identify the main physical components responsible for the fast multiwavelength variability of highly accreting compact objects.
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| 4. |
- Vincentelli, F. M., et al.
(author)
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Fast infrared variability from the black hole candidate MAXI J1535-571 and tight constraints on the modelling
- 2021
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 503:1, s. 614-624
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Journal article (peer-reviewed)abstract
- We present the results regarding the analysis of the fast X-ray/infrared (IR) variability of the black hole transient MAXI J1535-571. The data studied in thiswork consist of two strictly simultaneous observations performed with XMM-Newton (X-rays: 0.7-10 keV), VLT/HAWK-I (K-s band, 2.2 mu m) andVLT/VISIR (Mand PAH2 2 bands, 4.85 and 11.88 mu m, respectively). The cross-correlation function between the X-ray and near-IR light curves shows a strong asymmetric anticorrelation dip at positive lags. We detect a near-IR QPO (2.5 sigma) at 2.07 +/- 0.09 Hz simultaneously with an X-ray QPO at approximately the same frequency (f(0) = 2.25 +/- 0.05). From the cross-spectral analysis, a lag consistent with zero was measured between the two oscillations. We also measure a significant correlation between the average near-IR and mid-IR fluxes during the second night, but find no correlation on short time-scales. We discuss these results in terms of the two main scenarios for fast IR variability (hot inflow and jet powered by internal shocks). In both cases, our preliminary modelling suggests the presence of a misalignment between the disc and jet.
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| 5. |
- Balluchi, A., et al.
(author)
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Hybrid control of networked embedded systems
- 2005
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In: European Journal of Control. - : LAVOISIER. - 0947-3580 .- 1435-5671. ; 11:4-5, s. 478-508
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Journal article (peer-reviewed)abstract
- Hybrid systems that involve the interaction of continuous and discrete dynamics have been an active area of research for a number of years. In this paper, we start by briefly surveying the main theoretical control problems that have been treated in the hybrid systems setting and classify them into stabilization, optimal control and language specification problems. We then provide an overview of recent developments in four of the most prominent areas where these hybrid control methods have found application: control of power systems, industrial process control, design of automotive electronics and communication networks.
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| 6. |
- Haugaard-Kedström, Linda M., et al.
(author)
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A High-Affinity Peptide Ligand Targeting Syntenin Inhibits Glioblastoma
- 2021
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In: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 64:3, s. 1423-1434
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Journal article (peer-reviewed)abstract
- Despite the recent advances in cancer therapeutics, highly aggressive cancer forms, such as glioblastoma (GBM), still have very low survival rates. The intracellular scaffold protein syntenin, comprising two postsynaptic density protein-95/discslarge/zona occludens-1 (PDZ) domains, has emerged as a novel therapeutic target in highly malignant phenotypes including GBM. Here, we report the development of a novel, highly potent, and metabolically stable peptide inhibitor of syntenin, KSL-128114, which binds the PDZ1 domain of syntenin with nanomolar affinity. KSL-128114 is resistant toward degradation in human plasma and mouse hepatic microsomes and displays a global PDZ domain selectivity for syntenin. An X-ray crystal structure reveals that KSL128114 interacts with syntenin PDZ1 in an extended noncanonical binding mode. Treatment with KSL-128114 shows an inhibitory effect on primary GBM cell viability and significantly extends survival time in a patient-derived xenograft mouse model. Thus, KSL-128114 is a novel promising candidate with therapeutic potential for highly aggressive tumors, such as GBM.
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| 7. |
- Paice, J. A., et al.
(author)
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The evolution of rapid optical/X-ray timing correlations in the initial hard state of MAXIJ1820+070
- 2021
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 505:3, s. 3452-3469
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Journal article (peer-reviewed)abstract
- We report on a multiepoch campaign of rapid optical/X-ray timing observations of the superbright 2018 outburst of MAXIJ1820+070, a black hole low-mass X-ray binary system. The observations spanned 80 d in the initial hard state and were taken with NTT/ULTRACAM and GTC/HiPERCAM in the optical (u(s)g(s)r(s)i(s)z(s) filters at time resolutions of 8-300Hz) and with ISS/NICER in X-rays. We find (i) a growing anticorrelation between the optical and X-ray light curves, (ii) a steady, positive correlation at an optical lag of similar to 0.2s (with a longer lag at longer wavelengths) present in all epochs, and (iii) a curious positive correlation at negative optical lags in the last, X-ray softest epoch, with longer wavelengths showing a greater correlation and a more negative lag. To explain these, we postulate the possible existence of two synchrotron-emitting components - a compact jet and a hot flow. In our model, the significance of the jet decreases over the outburst, while the hot flow remains static (thus, relatively, increasing in significance). We also discuss a previously discovered quasi-periodic oscillation and note how it creates coherent optical time lags, stronger at longer wavelengths, during at least two epochs.
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