Jørgen Houe Pedersen

Fibrin clot structure in patients with end-stage renal disease

Fibrin clots with reduced permeability, increased clot stiffness and reduced fibrinolysis susceptibility may predispose to cardiovascular disease (CVD). Little is known, however, about the structure of fibrin clots in patients with end-stage renal disease (ESRD). These patients suffer from a high risk of CVD in addition to their chronic low-grade inflammation. Using permeability, compaction and turbidity studies in 22 ESRD patients and 24 healthy controls, fibrin clots made from patient plasma were found to be less permeable (p < 0.001), less compactable (p < 0.001), and less susceptible to fibrinolysis (p < 0.001) than clots from controls. The maximum rate of turbidity increase was also higher for the patients than controls (p < 0.001), and scanning electron microscopy revealed higher clot density of fibrin fibers in clots from patients than clots from controls (p < 0.001). Patients had higher plasma concentrations of fibrinogen, C-reactive protein and interleukin 6 than controls. These plasma markers of inflammation correlated significantly with most of the fibrin structure characteristics observed in the patients. In contrast, plasma markers of azothemia showed no such correlations. The results suggest that in ESRD patients fibrin clots are significantly different from healthy controls, and that the fibrin structure characteristics in the patients are associated primarily with the inflammatory plasma milieu rather than with level of azothemia.

Determination of size distributions in nanosized powders by TEM, XRD, and SAXS

Crystallite size distributions and particle size distributions were determined by transmissions electron microscopy (TEM), X-ray powder diffraction (XRD), and small-angle X-ray scattering (SAXS) for three commercially available TiO2 powders (P25, UV100, and TiO2_5 nm) and one SSEC produced powder (SSEC78). The theoretical Guinier model was fitted to the experimental obtained XRD data and compared to analytical expressions. Modeling of the XRD spectra showed a difference between the analytical size dependent expressions and the theoretical Guinier model. Primary particle size distributions were extracted from SAXS measurements by the hard sphere model including an interparticle interference factor. The sizes obtained from SAXS were smaller than the sizes obtained from the XRD experiments; however, a good agreement was obtained between the two techniques. Electron microscopy confirmed the primary particle sizes and the shapes obtained by XRD and SAXS. The SSEC78 powder and the commercially available powders showed different morphologies, but SSEC78, UV100, and TiO2_5 nm all consisted of both primary particles as well as a secondary structure comprised of nanosized primary particles agglomeration into larger clusters. P25 showed the largest primary particle size, but did not show a secondary structure.

Model-Based Control of a Nonlinear One Dimensional Magnetic Levitation with a Permanent-Magnet Object

The Electromagnet levitation technique has been popularly used in transport and industrial felds in recent decades, such as high-speed levitation trains, frictionless magnetic bearings, and high precision control in semiconductor manufacturing (CST (1996); Kim et al. (1998)). Due to its high efficiency and good environmental orientation, the application of this technique is extensively growing. For instance, the attitude of a small-sized satellite can be efficiently controlled by using the electromagnetic force generated from the interaction between the onboard (controlled) electrical field and the earth magnetic field (Wisniewski & Stoustrup (2004)).

Electromagnetic surface waves on a free-electron-like medium in the presence of a DC current: the dispersion relation

Abstract Within the framework of the so-called semiclassical infinite-barrier (SCIB) model, a non-local dispersion relation for electromagnetic surface waves (SEWs) on a free-electron-like medium in which a DC current is flowing is established. When the drift velocity of the carriers has a non-zero component along an axis perpendicular to the plane of propagation of the SEWs, our new dispersion relation predicts the existence of surface waves with a mixed state of s- and p-polarizations. Limiting ourselves to the hydrodynamic approximation, which allows the presence of collective excitations in the electron gas only, and to the case where the drift velocity is parallel to the propagation direction of the surface waves, we have carried out an elaborated study of the p-polarized SEW dispersion relation. A numerical calculation of the six branches of the dispersion relation has been carried out for n-InSb. Our calculations show that the “local” surface polaritons and the “electrostatic” surface plasmons in the presence of the DC current interact in the frequency regime ω p ϵ ∞ (ϵ ∞ + 1) lsim; ω ≲ ω p ϵ ∞ (ϵ ∞ − 1) . Significant modifications relation are found including new connections of branches. For certain frequencies the dispersion relation obtained predicts the existence of SEW instabilities.

A Nonlocal Description Of The Dispersion Relation And The Energy Flow Associated With Surface Electromagnetic Waves On Metals

The nonlocal dispersion relation for electromagnetic surface waves on a metal-vacuum surface, obtained within the framework of the semiclassical infinite-barrier model, is reviewed. Limiting ourselves to the hydrodynamic approach, which allows collective excitations in the electron gas only, we have for the first time determined and identified the branches of the nonlocal dispersion relation, completely. Also, we address the question of how to treat the stationary energy flow associated with electromagnetic surface waves in the nonlocal regime.

Fatigue Fracture of Gamma Nail

We report a case of a fatigue fracture of a Gamma nail in a patient with an unstable oblique subtrochanteric fracture, together with scanning electron microscopy analysis of the fracture surface. In contrast to other published cases, the fracture was in the part of the nail distal to the insertion point of the lag screw.

On the Structure of the Eigenmodes of Surface Electromagnetic Waves on Metals

Abstract On the basis of a rather general non-local dispersion relation for surface electromagnetic waves on metals, the wavevector components perpendicular to the surface are discussed. The discussion is restricted to an analysis of the mode structure in a narrow frequency region around the plasma edge of the metal, because the hydrodynamic model has been used to reduce the non-local dispersion relation.

Application of infra-red surface electromagnetic waves on metals in nondestructive surface testing

Abstract The elementary theory of surface electromagnetic waves (SEW), based on a local relation between the induced current density and electric field, is discussed. Based on this theory, typical values of propagation lengths and penetration depths are calculated in the infra-red and visible regions. Experiments using a double-prism configuration have been performed to demonstrate the relative coupling efficiency as a function of prism-gap height and angle of incidence, respectively, for infra-red SEWs. Approximate calculations of propagation lengths for infra-red SEWs on rough surfaces are presented.