Sweden: Political Developments and Data in 2019

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The structure of mixed H2O-OH monolayer films on Ru(0001)

Scanning tunneling microscopy (STM) and x-ray absorption spectroscopy (XAS) have been used to study the structures produced by water on Ru(0001) at temperatures above 140 K. It was found that while undissociated water layers are metastable below 140 K, heating above this temperature produces drastic transformations whereby a fraction of the water molecules partially dissociate and form mixed H{sub 2}O-OH structures. XPS and XAS revealed the presence of hydroxyl groups with their O-H bond essentially parallel to the surface. STM images show that the mixed H{sub 2}O-OH structures consist of long narrow stripes aligned with the three crystallographic directions perpendicular to the close-packed atomic rows of the Ru(0001) substrate. The internal structure of the stripes is a honeycomb network of H-bonded water and hydroxyl species. We found that the metastable low temperature molecular phase can also be converted to a mixed H{sub 2}O-OH phase through excitation by the tunneling electrons when their energy is 0.5 eV or higher above the Fermi level. Structural models based on the STM images were used for Density Functional Theory optimizations of the stripe geometry. The optimized geometry was then utilized to calculate STM images for comparison with the experiment

Clostridium difficile infection after cardiac surgery: Prevalence, morbidity, mortality, and resource utilization

ObjectiveDespite increasing efforts to prevent infection, the prevalence of hospital-associated Clostridium difficile infections (CDI) is increasing. Heightened awareness prompted this study of the prevalence and morbidity associated with CDI after cardiac surgery.MethodsA total of 22,952 patients underwent cardiac surgery at Cleveland Clinic from January 2005 to January 2011. CDI was diagnosed by enzyme immunoassay for toxins and, more recently, polymerase chain reaction (PCR) testing. Hospital outcomes and long-term survival were compared with those of the remaining population in propensity-matched groups.ResultsOne hundred forty-five patients (0.63%) tested positive for CDI at a median of 9 days postoperatively, 135 by enzyme immunoassay and 11 by PCR. Its prevalence more than doubled over the study period. Seventy-seven patients (48%) were transfers from outside hospitals. Seventy-three patients (50%) were exposed preoperatively to antibiotics and 79 (56%) to proton-pump inhibitors. Patients with CDI had more baseline comorbidities, more reoperations, and received more blood products than patients who did not have CDI. Presenting symptoms included diarrhea (107; 75%), distended abdomen (48; 34%), and abdominal pain (27; 19%). All were treated with metronidazole or vancomycin. Sixteen patients (11%) died in hospital, including 5 of 10 who developed toxic colitis; 3 of 4 undergoing total colectomy survived. Among matched patients, those with CDI had more septicemia (P < .0001), renal failure (P = .0002), reoperations (P < .0001), prolonged postoperative ventilation (P < .0001), longer hospital stay (P < .0001), and lower 3-year survival, 52% versus 64% (P = .03), than patients who did not have CDI.ConclusionsAlthough rare, the prevalence of CDI is increasing, contributing importantly to morbidity and mortality after cardiac surgery. If toxic colitis develops, mortality is high, but colectomy may be lifesaving

The dissipative linear Boltzmann equation for hard spheres

We prove the existence and uniqueness of an equilibrium state with unit mass to the dissipative linear Boltzmann equation with hard--spheres collision kernel describing inelastic interactions of a gas particles with a fixed background. The equilibrium state is a universal Maxwellian distribution function with the same velocity as field particles and with a non--zero temperature lower than the background one, which depends on the details of the binary collision. Thanks to the H--theorem we then prove strong convergence of the solution to the Boltzmann equation towards the equilibrium.Comment: 17 pages, submitted to Journal of Statistical Physic

Uncertainty quantification for kinetic models in socio-economic and life sciences

Kinetic equations play a major rule in modeling large systems of interacting particles. Recently the legacy of classical kinetic theory found novel applications in socio-economic and life sciences, where processes characterized by large groups of agents exhibit spontaneous emergence of social structures. Well-known examples are the formation of clusters in opinion dynamics, the appearance of inequalities in wealth distributions, flocking and milling behaviors in swarming models, synchronization phenomena in biological systems and lane formation in pedestrian traffic. The construction of kinetic models describing the above processes, however, has to face the difficulty of the lack of fundamental principles since physical forces are replaced by empirical social forces. These empirical forces are typically constructed with the aim to reproduce qualitatively the observed system behaviors, like the emergence of social structures, and are at best known in terms of statistical information of the modeling parameters. For this reason the presence of random inputs characterizing the parameters uncertainty should be considered as an essential feature in the modeling process. In this survey we introduce several examples of such kinetic models, that are mathematically described by nonlinear Vlasov and Fokker--Planck equations, and present different numerical approaches for uncertainty quantification which preserve the main features of the kinetic solution.Comment: To appear in "Uncertainty Quantification for Hyperbolic and Kinetic Equations

Catalysis in Real Time Using X-Ray Lasers

We describe how the unique temporal and spectral characteristics of X-ray free-electron lasers (XFEL) can be utilized to follow chemical transformations in heterogeneous catalysis in real time. We highlight the systematic study of CO oxidation on Ru(0001), which we initiate either using a femtosecond pulse from an optical laser or by activating only the oxygen atoms using a THz pulse. We find that CO is promoted into an entropy-controlled precursor state prior to desorbing when the surface is heated in the absence of oxygen, whereas in the presence of oxygen, CO desorbs directly into the gas phase. We monitor the activation of atomic oxygen explicitly by the reduced split between bonding and antibonding orbitals as the oxygen comes out of the strongly bound hollow position. Applying these novel XFEL techniques to the full oxidation reaction resulted in the surprising observation of a significant fraction of the reactants at the transition state through the electronic signature of the new bond formation