| 1. |
- Caronna, Edoardo, et al.
(författare)
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Redefining migraine prevention: early treatment with anti-CGRP monoclonal antibodies enhances response in the real world
- 2024
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Ingår i: JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY. - 0022-3050 .- 1468-330X.
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Tidskriftsartikel (refereegranskat)abstract
- Background Anti-CGRP monoclonal antibodies (anti-CGRP MAbs) are approved and available treatments for migraine prevention. Patients do not respond alike and many countries have reimbursement policies, which hinder treatments to those who might respond. This study aimed to investigate clinical factors associated with good and excellent response to anti-CGRP MAbs at 6 months. Methods European multicentre, prospective, real-world study, including high-frequency episodic or chronic migraine (CM) patients treated since March 2018 with anti-CGRP MAbs. We defined good and excellent responses as >= 50% and >= 75% reduction in monthly headache days (MHD) at 6 months, respectively. Generalised mixed-effect regression models (GLMMs) were used to identify variables independently associated with treatment response. Results Of the 5818 included patients, 82.3% were females and the median age was 48.0 (40.0-55.0) years. At baseline, the median of MHD was 20.0 (14.0-28.0) days/months and 72.2% had a diagnosis of CM. At 6 months (n=4963), 56.5% (2804/4963) were good responders and 26.7% (1324/4963) were excellent responders. In the GLMM model, older age (1.08 (95% CI 1.02 to 1.15), p=0.016), the presence of unilateral pain (1.39 (95% CI 1.21 to 1.60), p<0.001), the absence of depression (0.840 (95% CI 0.731 to 0.966), p=0.014), less monthly migraine days (0.923 (95% CI 0.862 to 0.989), p=0.023) and lower Migraine Disability Assessment at baseline (0.874 (95% CI 0.819 to 0.932), p<0.001) were predictors of good response (AUC of 0.648 (95% CI 0.616 to 0.680)). These variables were also significant predictors of excellent response (AUC of 0.691 (95% CI 0.651 to 0.731)). Sex was not significant in the GLMM models. Conclusions This is the largest real-world study of migraine patients treated with anti-CGRP MAbs. It provides evidence that higher migraine frequency and greater disability at baseline reduce the likelihood of responding to anti-CGRP MAbs, informing physicians and policy-makers on the need for an earlier treatment in order to offer the best chance of treatment success.
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| 2. |
- Björklund Svensson, Jonas, et al.
(författare)
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Low-divergence femtosecond X-ray pulses from a passive plasma lens
- 2021
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2481 .- 1745-2473. ; 17:5, s. 639-645
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Tidskriftsartikel (refereegranskat)abstract
- Electron and X-ray beams originating from compact laser-wakefield accelerators have very small source sizes that are typically on the micrometre scale. Therefore, the beam divergences are relatively high, which makes it difficult to preserve their high quality during transport to applications. To improve on this, tremendous efforts have been invested in controlling the divergence of the electron beams, but no mechanism for generating collimated X-ray beams has yet been demonstrated experimentally. Here we propose and realize a scheme where electron bunches undergoing focusing in a dense, passive plasma lens can emit X-ray pulses with divergences approaching the incoherent limit. Compared with conventional betatron emission, the divergence of this so-called plasma lens radiation is reduced by more than an order of magnitude in solid angle, while maintaining a similar number of emitted photons per electron. This X-ray source offers the possibility of producing brilliant and collimated few-femtosecond X-ray pulses for ultra-fast science, in particular for studies based on X-ray diffraction and absorption spectroscopy. X-ray pulses with low divergences are produced in a laser-wakefield accelerator by focusing electron bunches in a dense passive plasma lens.
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| 3. |
- Desforges, F. G., et al.
(författare)
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Analysis of Electron Injection in Laser Wakefield Acceleration Using Betatron Emission in Capillary Tubes
- 2015
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Ingår i: Laser Acceleration of Electrons, Protons, and Ions III; and Medical Applications of Laser-Generated Beams of Particles III. - : SPIE. - 1996-756X .- 0277-786X. ; 9514, s. 95140-95140
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Konferensbidrag (refereegranskat)abstract
- The dynamics of ionization-induced electron injection in the high density (similar to 1.2 x 10(19)cm(-3)) regime of Laser Wakefield Acceleration (LWFA) was investigated by analyzing betatron X-ray emission inside dielectric capillary tubes. A comparative study of the electron and betatron X-ray properties was performed for both self-injection and ionization-induced injection. Direct experimental evidence of early onset of ionization-induced injection into the plasma wave was obtained by mapping the X-ray emission zone inside the plasma. Particle-In-Cell (PIC) simulations showed that the early onset of ionization-induced injection, due to its lower trapping threshold, suppresses self-injection of electrons. An increase of X-ray fluence by at least a factor of two was observed in the case of ionization-induced injection due to an increased trapped charge compared to self-injection mechanism.
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| 4. |
- Diego, Guénot, et al.
(författare)
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Simultaneous X-ray absorption and two-photon LIF for imaging the spray formation region
- 2019
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Ingår i: ILASS–Europe 2019, Proceedings of the 29th Conference on Liquid Atomization and Spray Systems, 2-4 September 2019, Paris, France.
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Konferensbidrag (refereegranskat)abstract
- Imaging the spray formation region of atomizing sprays is particularly challenging due to the presence of a variety of irregular liquid structures such as ligaments, liquid blobs, droplets, liquid sheets and a possible liquid core. The number and concentration of those liquid bodies dictate the presence of liquid/air interfaces, which are responsible to undesired scattering effects. The resulting images are blurred, ultimately concealing the real structure of the spray formation region. Due to both, scattering effects and the presence of highly irregular 3D liquid structures, the only reliable measurement of liquid mass in the spray formation region is obtained using X-ray radiography. The generation of collimated X-rays pulsed has been done, in the past, by means of a synchrotron, thus limiting the number of studies that can be performed.In parallel to the use of X-rays, progresses in advanced laser imaging techniques for suppressing multiple scattering issues have been particularly important over the past decade. A very recent solution consists in using 2-photon excitation LIF laser sheet imaging.In this paper, we report for the first time the possibility of simultaneously imaging an atomizing spray using X-ray absorption and 2-photon LIF planar imaging, where the simultaneous single-shot recordings are made over a ~20mmx20mm viewed area. The spray is generated from a commercial fuel port injection system from which, water was injected. The unique illumination/detection scheme proposed here was made possible thanks to the use of X-rays emitted from a laser plasma accelerator (Betatron radiation). For this experiment, we use the High Intensity Laser system at Lund University that provides on target 800mJ, 38fs laser pulses. The emitted X-ray radiation is ranging from 1 to 10keV and peaking at ~2keV. It propagates outside of the vacuum chamber where an X-ray camera records the shadow of the liquid jet. In addition to that, a fraction of the laser pulse ~10mJ is directed on the liquid jet and focuses with a cylindrical lens where it induces fluorescence from a 2-photon excitation process in a dye -here, fluorescein- added to the liquid. The 2p-LIF images provide details on the size and shape of the liquid structures, optically sectioned by the light sheet, while the integrated liquid mass is extracted from the X-ray radiography. This is making the two imaging techniques highly complementary for the characterization of spray systems as well as for further understanding the physics related to liquid atomization.
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| 5. |
- Ekerfelt, Henrik, et al.
(författare)
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A tunable electron beam source using trapping of electrons in a density down-ramp in laser wakefield acceleration
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- One challenge in the development of laser wakefield accelerators is to demonstrate sufficient control and reproducibility of the parameters of the generated bunches of accelerated electrons. Here we report on a numerical study, where we demonstrate that trapping using density down-ramps allows for tuning of several electron bunch parameters by varying the properties of the density down-ramp. We show that the electron bunch length is determined by the difference in density before and after the ramp. Furthermore, the transverse emittance of the bunch is controlled by the steepness of the ramp. Finally, the amount of trapped charge depends both on the density difference and on the steepness of the ramp. We emphasize that both parameters of the density ramp are feasible to vary experimentally. We therefore conclude that this tunable electron accelerator makes it suitable for a wide range of applications, from those requiring short pulse length and low emittance, such as the free-electron lasers, to those requiring high-charge, large-emittance bunches to maximize betatron X-ray generation.
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| 6. |
- Gallardo Gonzalez, Isabel
(författare)
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Development and Applications of a Laser-Wakefield X-ray Source
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In laser-wakefield acceleration (LWFA), a femtosecond laser pulse is tightly focused in a gas to intensities exceeding 1018 W/cm2 . The laser radiation ionizes the medium and excites a plasma wave that travels behind the laser pulse. Electrons can be trapped in the oscillations in the plasma density, where electric fields of the order of several hundreds of GV/m accelerate them to relativistic energies. Together with the longitudinal accelerating fields, transverse electromagnetic forces keep the electrons oscillating in the three-dimensional plasma structure around the direction of propagation of the laser. These betatron oscillations cause the emission of X-ray pulses with a broadband spectrum and femtosecond duration.The emission of such relativistic electron beams and ultrashort X-ray pulses, due to the high accelerating fields that can be sustained in the plasma, promises a new generation of compact electron accelerators. However, the complexity of the nonlinear laser–plasma interaction that produces LWFA poses challenges in the reproducibility and control of both the electron beams and the X-ray pulses.The main goals of the present work are the optimization and application of a LWFA-based X-ray source. The mechanism through which the electrons are trapped and accelerated in the plasma wave influences the final parameters governing both the electrons and X-rays. Several trapping mechanisms have been investigated: using gas mixtures, a plasma density down-ramp and a combination of the two. The advantages of these approaches were a general improvement in the shot-to-shot reproducibility and some control of the electron beam charge and spectrum. It is shown that an increase in the dopant concentration of the gas also affects the acceleration process, as it increases the contribution to the electron energy from direct laser acceleration (DLA), where the overlap of the laser fields with the charge trapped in the plasma wave led to higher transverse and longitudinal electron momenta. By the intersection of two laser pulses in the plasma, the merging of two laser wakefields is experimentally observed, producing the emission of one single electron beam and X-rays in the forward direction. Due to their effect on the electron transverse momentum, DLA and wakefield merging are expected to increase the total emission of X-rays produced by LWFA.Regarding potential uses of the X-ray source, several experiments presented here demonstrated the applicability of betatron X-rays for scientific studies in different disciplines. Phase-contrast imaging of an insect and an alloy demonstrated the resolution of a few micrometres that is possible with betatron radiation. The source was also used to test an X-ray absorption spectrometer designed for a femtosecond time-resolved study of hot plasmas with a LWFA-based X-ray source.
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| 7. |
- Gallardo Gonzalez, Isabel
(författare)
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Development and Applications of a Laser-Wakefield X-ray Source (updated)
- 2019. - 2
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In laser-wakefield acceleration (LWFA), a femtosecond laser pulse is tightly focused in a gas to intensities exceeding 1018 W/cm2 . The laser radiation ionizes the medium and excites a plasma wave that travels behind the laser pulse. Electrons can be trapped in the oscillations in the plasma density, where electric fields of the order of several hundreds of GV/m accelerate them to relativistic energies. Together with the longitudinal accelerating fields, transverse electromagnetic forces keep the electrons oscillating in the three-dimensional plasma structure around the direction of propagation of the laser. These betatron oscillations cause the emission of X-ray pulses with a broadband spectrum and femtosecond duration.
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| 8. |
- Reinhold, Isabella, et al.
(författare)
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Quality of Academic Writing for Engineering Students at Lund University
- 2017
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Ingår i: Transforming patterns through the scholarship of teaching and learning : the 2nd European conference for the scholarship of teaching and learning | Lund, Sweden, June 8-9 2017 - the 2nd European conference for the scholarship of teaching and learning | Lund, Sweden, June 8-9 2017.
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Konferensbidrag (refereegranskat)abstract
- The development of good writing skills is fundamental not only to publish scientific results, but also to have a deeper understanding of complex subjects. However reports from the Swedish Higher Education Authority from 2012-2015 suggest that engineering students at Lund University have unsatisfactory academic writing skills. Our paper investigates how students of the Faculty of Engineering at Lund University perceive academic writing and the effects of a writing intervention.To obtain information on students’ education in, attitude, perception of its difficulty and their own skill towards academic writing, we constructed a survey which was sent out to engineering students at Lund University. This yielded 62 responses showing that students want more opportunities to develop their writing, but that they grade their writing skill high and the difficulty low.The effects of a simple writing intervention, briefly discussing the importance of good writing practices during a laboratory session, was investigated for one student group. This was done using a random selection of laboratory reports for one control group and one intervention group. The overall quality of the students’ writing was not significantly improved with the intervention. However the quality of the conclusions, the report section with the lowest quality rating, was higher for the intervention group.
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| 9. |
- Svendsen, Kristoffer, et al.
(författare)
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Optimization of soft X-ray phase-contrast tomography using a laser wakefield accelerator
- 2018
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Ingår i: Optics Express. - 1094-4087. ; 26:26, s. 33930-33941
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Tidskriftsartikel (refereegranskat)abstract
- X-ray phase-contrast imaging allows for non-invasive analysis in low-absorbing materials, such as soft tissue. Its application in medical or materials science has yet to be realized on a wider scale due to the requirements on the X-ray source, demanding high flux and small source size. Laser wakefield accelerators generate betatron X-rays fulfilling these criteria and can be suitable sources for phase-contrast imaging. In this work, we present the first phase-contrast images obtained by using ionization injection-based laser wakefield acceleration, which results in a higher photon yield and smoother X-ray beam profile compared to self-injection. A peak photon yield of 1.9 × 1011 ph/sr and a source size of 3 μm were estimated. Furthermore, the current laser parameters produce an X-ray spectrum mainly in the soft X-ray range, in which laser-plasma based phase-contrast imaging had yet to be studied. The phase-contrast images of a Chrysopa lacewing resolve features on the order of 4 μm. These images are further used for a tomographic reconstruction and a volume rendering, showing details on the order of tens of μm.
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| 10. |
- Tomkus, Vidmantas, et al.
(författare)
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Laser wakefield accelerated electron beams and betatron radiation from multijet gas targets
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Laser Plasma Wakefield Accelerated (LWFA) electron beams and efficiency of betatron X-ray sources is studied using laser micromachined supersonic gas jet nozzle arrays. Separate sections of the target are used for the injection, acceleration and enhancement of electron oscillation. In this report, we present the results of LWFA and X-ray generation using dynamic gas density grid built by shock-waves of colliding jets. The experiment was done with the 40 TW, 35 fs laser at the Lund Laser Centre. Electron energies of 30–150 MeV and 1.0 × 108–5.5 × 108 photons per shot of betatron radiation have been measured. The implementation of the betatron source with separate regions of LWFA and plasma density grid raised the efficiency of X-ray generation and increased the number of photons per shot by a factor of 2–3 relative to a single-jet gas target source.
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