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Researchers have measured superfluid helium’s full dispersion spectrum, explaining discrepancies in previous studies and constraining theories of superfluidity.

Tillsammans med industrin utvecklar vi nya idéer inom material, tillverkning och materialåtervinning. Målet är att hitta lösningar som både ser till miljön och stärker företagens konkurrenskraft. Industrin förbrukar cirka en tredjedel av Sveriges energi och mycket av miljöbelastningen av vår konsumtion kommer från material som finns i bruksprodukter som exempelvis redskap, hushållsmaskiner och for

https://www.lu.se/forskning/fokusomraden/strategiska-forskningsomraden/hallbar-produktion - 2026-07-13

Isolated attosecond pulse (IAP) generation usually involves the use of short-medium gas cells operated at high pressures. In contrast, long-medium schemes at low pressures are commonly perceived as inherently unsuitable for IAP generation due to the nonlinear phenomena that challenge favourable phase-matching conditions. Here we provide clear experimental evidence on the generation of isolated ext

This survey concerns optimization problems arising in the design of survivable communication networks. It turns out that such problems can be modeled in a natural way as non-compact linear programming formulations based on multicommodity flow network models. These non-compact formulations involve an exponential number of path flow variables, and therefore require column generation to be solved to

In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the resonator wavelength can be naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in singlepass linac-based devices, the electron beam is re-circulated in the storage ring and, while the microbunching becomes "thermalized" from turn to turn, the evolution of other bunch

We present a completely ab initio calculation of harmonic generation in xenon exposed to a strong laser field. The time-dependent Schrödinger equation for the atomic response and the propagation equation are numerically integrated yielding excellent agreement with experiment. The weaker variation with pump intensity of the induced dipole in the high-field regime leads to an enormous enhancement in

This paper deals with path-based linear programming formulations in survivable network design. In a recent survey we have investigated the complexity of the column generation problems for a large variety of protection and restoration mechanisms in a single or multiple link failure scenario, and classified them according to their structure. It turned out that all the considered column generation pr

This thesis concerns a sociological analysis on the role of generations in the processes of the construction of national identities, and long-distance nationalism in diasporic settings. The empirical case taken is a political generation of Kurds from Turkey who once arrived in Sweden as political refugees. The primary aim of the thesis is to study how national identities are constructed and maint

The polarization direction of an electromagnetic field changes and eventually reaches a steady state when propagating through a birefringent material with off-axis absorption or gain. The steady state orientation direction depends on the magnitude of the absorption (gain) and the phase retardation rate. The change in the polarization direction is experimentally demonstrated in weakly doped (0.05%)

Generally regarded as a sustainable country, Costa Rica faces the future challenge of maintaining their renewable energy performance amidst climate change impacts and the need to integrate intermittent renewables. This thesis explores the opportunities and barriers for Costa Rica to achieve 100% renewable electricity while maintaining energy security, despite its developing nation status. Through

The modernization of China comes as one of the most interesting topics not only at this moment but also has been researched for a long time. The individualization theories come as a result of modernity. This thesis draws on ten in-depth interviews in order to analyze the individualization among the educated, middle-class young people who were born in the 1990s by testing Yan Yunxiang’s theories of

Mexico has experienced the dramatic escalation of crime and violence in an organized form since the 1990s, and have also witnessed the highest number of homicides in the last ten years. It has adversely affected the national security, economic growth and social development with an especially detrimental effect on youth in Mexico. This study examines the direct and indirect impacts of drug trade-re

In this paper, a novel detection scheme for the monitoring of insect ecosystems is presented. Our method is based on the remote acquisition of passive sunlight scattering by two insect species. Procedures to identify rare events in remote dark-field spectroscopy are explained. We further demonstrate how to reduce the spectral representation, and how to discriminate between sexes, using a hierarchi

Using an eight-band k . p model Hamiltonian with the Burt-Foreman envelope function theory, we have investigated the optical absorption of both linearly and circularly polarized light, as well as related phenomena in InAs/GaSb broken-gap quantum wells grown along the [0 0 1] direction, with emphasis on the effects of electron-hole hybridization and the various symmetry-breaking mechanisms such as

High-dimensional systems are an important frontier for photonic quantum correlation experiments. These correlation tests commonly prescribe measurements with many possible outcomes but they are often implemented through many individual binary-outcome measurements that use only a single-detector. Here, we discuss how this binarization procedure for multioutcome measurements can open a loophole, unl

Summary. Previous data have shown an inter-individual difference in the thrombin generating capacity in vitro as well as phenotypic bleeding pattern among patients with severe haemophilia A (FVIII:C activity below 1%). The reason for this is not known. In addition, there are no reports on how thrombin generation may correlate between siblings. In this study, we evaluated and compared thrombin gene

The optical spectra of a quantum cascade laser structure under nonequilibrium conditions is studied using the technique of nonequilibrium Green functions. We focus on the impact of Coulomb corrections and their dependence on the operating conditions. The role of the static mean field due to the charge distribution by electrons and ioninzed donors is investigated.