Nonequilibrium Green's functions and atom-surface dynamics: Simple views from a simple model system

We employ Non-equilibrium Green's functions (NEGF) to describe the real-time dynamics of an adsorbate-surface model system exposed to ultrafast laser pulses. For a finite number of electronic orbitals, the system is solved exactly and within different levels of approximation. Specifically i) the full exact quantum mechanical solution for electron and nuclear degrees of freedom is used to benchmark ii) the Ehrenfest approximation (EA) for the nuclei, with the electron dynamics still treated exactly. Then, using the EA, electronic correlations are treated with NEGF within iii) 2nd Born and with iv) a recently introduced hybrid scheme, which mixes 2nd Born self-energies with non-perturbative, local exchange-correlation potentials of Density Functional Theory (DFT). Finally, the effect of a semi-infinite substrate is considered: we observe that a macroscopic number of de-excitation channels can hinder desorption. While very preliminary in character and based on a simple and rather specific model system, our results clearly illustrate the large potential of NEGF to investigate atomic desorption, and more generally, the non equilibrium dynamics of material surfaces subject to ultrafast laser fields.Comment: 10 pages, 5 figure

Compositional nanodomain formation in hybrid formate perovskites

We report the synthesis and structural characterisation of three mixed-metal formate perovskite families [C(NH$_2$)$_3$]M$_{1-x}$Cu$_x$(HCOO)$_3$ (M = Mn, Zn, Mg). Using a combination of infrared spectroscopy, non-negative matrix factorization, and reverse Monte Carlo refinement, we show that the Mn- and Zn-containing compounds support compositional nanodomains resembling the polar nanoregions of conventional relaxor ferroelectrics. The M = Mg family exhibits a miscibility gap that we suggest reflects the limiting behaviour of nanodomain formation.Comment: 4 pages, 3 figure

Controlling the magnetic state of the proximate quantum spin liquid α-RuCl₃ with an optical cavity

Harnessing the enhanced light-matter coupling and quantum vacuum fluctuations resulting from mode volume compression in optical cavities is a promising route towards functionalizing quantum materials and realizing exotic states of matter. Here, we extend cavity quantum electrodynamical materials engineering to correlated magnetic systems, by demonstrating that a Fabry-Pérot cavity can be used to control the magnetic state of the proximate quantum spin liquid α-RuCl3. Depending on specific cavity properties such as the mode frequency, photon occupation, and strength of the light-matter coupling, any of the magnetic phases supported by the extended Kitaev model can be stabilized. In particular, in the THz regime, we show that the cavity vacuum fluctuations alone are sufficient to bring α-RuCl3 from a zigzag antiferromagnetic to a ferromagnetic state. By external pumping of the cavity in the few photon limit, it is further possible to push the system into the antiferromagnetic Kitaev quantum spin liquid state

VACCINATION AGAINST SWINE FLU CAUSED NARCOLEPSY IN SEVERAL EUROPEAN COUNTRIES

Publisher Copyright: © 2020 Boström I., Lindberger O., Partinen M., Landtblom A.M. All Rights Reserved.Narcolepsy is a rare sleeping disorder that gives sleep onset rapid eye movement periods and excessive daytime sleepiness. It is divided into two subgroups, narcolepsy type 1 where there also is orexin deficiency and cataplexy and narcolepsy type 2 that lack these features. Narcolepsy type 1 is assumed to be an autoimmune disease with destruction of orexin-producing cells. The pathology behind is unclear. There is a strong association to a class II HLA allele, HLADQB1*06:02 and the H1N1-virus and streptococcal infections has also been associated with narcolepsy. The severity of narcolepsy differs between patients from those who can manage their disease without medication to those who has a severe impact on their everyday life. There is a diagnostic delay between the onset of symptoms and time for diagnosis that in some cases can be more than a decade. The global mean prevalence is 30 per 100 000 inhabitants. The incidence in children in northern Europe has risen since 2010. An early study of the 2009 H1N1 influenza A pandemic indicated a high mortality and prompted efforts to rapidly come up with a vaccine. One of these was Pandemrix that was the most widely used in Europe and 61 % of the inhabitants in Sweden was vaccinated. Studies have shown an increased incidence of narcolepsy type 1 in European countries that had used Pandemrix, but no increased risk was seen in countries that had used other vaccines than Pandemrix.Peer reviewe

Individual and organisational factors in the psychosocial work environment are associated with home care staffs’ job strain: A Swedish cross-sectional study

Background Home care staff (HCS) provide essential service to enable older adults to age in place. However, unreasonable demands in the work environment to deliver a safe, effective service with high quality has a negative impact on the individual employee’s well-being and the care provided to the older adults. The psychosocial work environment is associated with employees´ well-being, although, knowledge regarding which individual and organisational factors that contribute to job strain for HCS is limited. These factors need to be identified to develop targeted interventions and create sustainable work situations for HCS. This study aimed to explore how HCS´s perceived job strain is associated with, and to what extent can be explained by, individual and organisational factors of the psychosocial work environment and psychosomatic health. Method An explorative cross-sectional questionnaire survey design was used in a large Swedish county. Five home care agencies with a total of 481 HCS were asked to respond to a questionnaire regarding their perceived level of job strain (Strain in Dementia Care Scale), psychosocial work environment (QPSNordic34+), and psychosomatic health (Satisfaction with Work Questionnaire). Multiple linear regression (MLR) analyses were conducted to explore the association between job strain and individual and organisational factors. Results In total, 226 (46%) HCS responded to the questionnaire. Both individual and organisational factors were significant predictors of job strain and explained a variance ranging between 39 to 51% (p = 0.001). The organisational factor job demand and the individual factor feeling worried and restless was most frequently represented in these MRL models. A higher job strain was also associated with adverse outcomes regarding leadership, organisational culture and climate, and control at work. Conclusion This study indicates that there is an intertwined complexity of individual and organisational factors that are associated with the HCS´s perception of job strain. Implementation of new multidimensional work strategies, such as a reablement approach, could support the development of efficient strategies for HCS and reduce the level of job strain. Policy changes for the provision of home care are also needed to support the development of a sustainable and healthy psychosocial work environment

Charge separation in donor-C60 complexes with real-time Green's functions: The importance of nonlocal correlations

We use the Nonequilibrium Green's Function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C60 complexes modeled by a Pariser-Parr-Pople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time-dependent Density Matrix Renormalization Group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical non-local correlation corrections are included. This CS process occurs in ~10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicate that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.Comment: 9 pages, 6 figures + supplemental information (4 pages)

Angiopoietin-2 predicts morbidity in adults with Fontan physiology.

Morbidity in patients with single-ventricle Fontan circulation is common and includes arrhythmias, edema, and pulmonary arteriovenous malformations (PAVM) among others. We sought to identify biomarkers that may predict such complications. Twenty-five patients with Fontan physiology and 12 control patients with atrial septal defects (ASD) that underwent cardiac catheterization were included. Plasma was collected from the hepatic vein and superior vena cava and underwent protein profiling for a panel of 20 analytes involved in angiogenesis and endothelial dysfunction. Ten (40%) of Fontan patients had evidence of PAVM, eighteen (72%) had a history of arrhythmia, and five (20%) were actively in arrhythmia or had a recent arrhythmia. Angiopoietin-2 (Ang-2) was higher in Fontan patients (8,875.4 ± 3,336.9 pg/mL) versus the ASD group (1,663.6 ± 587.3 pg/mL, p < 0.0001). Ang-2 was higher in Fontan patients with active or recent arrhythmia (11,396.0 ± 3,457.7 vs 8,118.2 ± 2,795.1 pg/mL, p < 0.05). A threshold of 8,500 pg/mL gives Ang-2 a negative predictive value of 100% and positive predictive value of 42% in diagnosing recent arrhythmia. Ang-2 is elevated among adults with Fontan physiology. Ang-2 level is associated with active or recent arrhythmia, but was not found to be associated with PAVM

Direct optical probe of magnon topology in two-dimensional quantum magnets

Controlling edge states of topological magnon insulators is a promising route to stable spintronics devices. However, to experimentally ascertain the topology of magnon bands is a challenging task. Here we derive a fundamental relation between the light-matter coupling and the quantum geometry of magnon states. This allows to establish the two-magnon Raman circular dichroism as an optical probe of magnon topology in honeycomb magnets, in particular of the Chern number and the topological gap. Our results pave the way for interfacing light and topological magnons in functional quantum devices