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The structural evolution of molecular hydrogen H2 under multi-megabar compression and its relation to atomic metallic hydrogen is a key unsolved problem in condensed-matter physics. Although dozens of crystal structures have been proposed by theory1, 2, 3–4, only one, the simple hexagonal-close-packed (hcp) structure of only spherical disordered H2, has been previously confirmed in experiments5. T
Electrons photoemitted by extreme ultraviolet attosecond pulses derive spatially from the first few atomic surface layers and energetically from the valence band and highest atomic orbitals. As a result, it is possible to probe the emission dynamics from a narrow 2D region in the presence of optical fields, as well as obtain elemental specific information. However, combining this with spatially-re
Within the FLASH2020+ upgrade, the pump-probe laser capabilities of the extreme ultraviolet and soft x-ray free-electron laser (XFEL) FLASH in Hamburg will be extended. In particular, providing wavelength tunability, shorter pulse durations, and reduced arrival time jitter will increase the scientific opportunities and the time resolution for the XFEL-optical laser pump-probe experiments. We prese
A novel regularization method for shape optimization of contacting structures is proposed. The shape optimization avoids parameterizations via splines or the level set method by directly optimizing the nodes in the finite element mesh. In the past this approach was limited by numerical difficulties arising from mesh entanglement and serrated boundaries but recent advances in regularization techniq
Attosecond pulses, produced through high-order harmonic generation in gases, have been successfully used for observing ultrafast, subfemtosecond electron dynamics in atoms, molecules and solid state systems. Today’s typical attosecond sources, however, are often impaired by their low repetition rate and the resulting insufficient statistics, especially when the number of detectable events per shot
The frequency modulation transfer property of a backward-wave optical parametric oscillator (BWOPO) is investigated in the context of near-IR pulse compression. The maximum transferrable bandwidth from the pump to the forward wave in a BWOPO is determined by the group dispersion mismatch. In comparison, the third-order phase introduced in a single-grating compressor setup is more detrimental to ac
The strict momentum conservation constraints for backward-wave optical parametric oscillators (BWOPOs) gives an inherently narrowband backward-generated wave, even with broadband pumping. Unfortunately, the limited tuning range of this wave restricts potential applications. Here we demonstrate a method to circumvent this restriction and increase the tuning range by more than one order of magnitude
Mirrorless optical parametric oscillators (MOPOs) are very attractive parametric devices that rely on the nonlinear interaction of counter-propagating photons to inherently establish distributed feedback, without the use of external mirrors or surface coatings. These devices offer unique spectral and coherence properties that will benefit a large variety of applications ranging from spectroscopy t
Strongly enhanced backward stimulated polariton scattering (BSPS) is demonstrated in periodically-poled KTiOPO4 (KTP) crystals with a high power-conversion efficiency up to 70%. We study the physical mechanism of such counter-propagating parametric interaction with phonon-polaritons in χ(2) modulated structures. BSPS is a three-wave mixing that is distinguished from backward stimulated Raman scatt
Combining high peak and high average power has long been a key challenge of ultrafast laser technology, crucial for applications such as laser-plasma acceleration and strong-field physics. A promising solution lies in post-compressed ytterbium lasers, but scaling these to high pulse energies presents a major bottleneck. Post-compression techniques, particularly Herriott-type multi-pass cells (MPCs
We report pulse energy scaling enabled by the use of Laguerre-Gaussian single-vortex (LG0,l) beams for spectral broadening in a sub-40 cm long Herriott-type bulk multi-pass cell. Beams with orders l=1−3 are generated by a spatial light modulator, which facilitates rapid and precise reconfiguration of the experimental conditions. 180 fs pulses with 610 uJ pulse energy are post-compressed to 44 fs u
BACKGROUND: Preeclampsia is a hypertensive pregnancy disorder marked by endothelial damage. Healthy endothelium is covered by a protective glycocalyx layer, which, when degraded, releases detectable products into the blood. Sphingosine-1phosphate (S1P) is a cardiovascular biomarker involved in glycocalyx preservation, linked to placentation and preeclampsia development. The study aimed to test the
Purpose: The aim of this study was to evaluate risk factors for postoperative pain and nausea after open repair for primary ventral hernias. Method: A population-based registry study was conducted based on data assembled from the Swedish national ventral hernia repair register between January 2016 and December 2021and cross-matched with the Swedish perioperative register. Results: Altogether 2064
Several of the requirements for obtaining a medical degree according to the Swedish Higher Education Ordinance illustrate the scientific basis of the profession, and systematic reviews as well as health technology assessments (HTA) constitute cornerstones in evidence-based medicine. In this study, medical students' experience of scientific education related to the profession was explored, and thei
Svensk Kolinlagring och Lunds universitet (LUCSUS) samlade 19 personer för en workshop på Torsåker gård i syfte att diskutera styrmedel och strategier för att öka kolinlagringen i jordbruksmark, och hur dessa verktyg skulle kunna utformas för att stödja en omställning till ett socialt och ekologiskt hållbart matsystem. Deltagarna representerade olika delar och nivåer av matsystemet och bidrog med
Objective: This study aimed to compare cumulative [fresh and frozen embryo transfers from one ovarian stimulation (OS) cycle] pregnancy and live birth rates in women for whom the choice between recombinant FSH (rFSH) and urinary FSH (uFSH) for OS was linked to FSH receptor (FSHR) N680S genotype and compared these to non-genotyped controls.Methods: To define the optimal combination of FSH type and
Objective: Extremes of prepregnancy maternal BMI increase neonatal mortality and morbidity at term. They also increase the risk of extremely preterm (EP, i.e., <27 weeks' gestational age) births. However, the association between maternal BMI and outcomes for EP babies is poorly understood. Methods: We used a cross-country design, bringing together the following three population-based, prospective,
