A damped forward EMI model for a horizontally stratified earth

If a magnetic dipole is placed above the surface of the earth, the Electromagnetic Induction (EMI) effect, encoded in Maxwell's equations, causes eddy currents in the soil which, on their turn, induce response electromagnetic fields. The magnetic field can be measured in geophysical surveys to determine the conductivity profile of the ground in a non-destructive manner. The forward model used in the inversion of experimental data usually consists of a set of horizontal homogeneous layers. A frequently used analytical model, proposed by McNeill, does not include the interaction between the eddy currents, and therefore fails for larger conductivities. In this paper we construct a new forward, analytical, model to estimate the magnetic field caused by a horizontally stratified earth but which approximates the interaction between eddy currents. This makes it valid for a broader range of parameters than the current state of the art. Furthermore, the error with the (numerically obtainable) exact result is substantially decreased. We also calculate the vertical sensitivity ("depth of exploration") of the model and observe that it is in good agreement with the values obtained from the exact model.Comment: Accepted for publication in Exploration Geophysic

Development of a new inactivated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine

Porcine reproductive and respiratory syndrome virus (PRRSV) is responsible for reproduction disorders in sows, which leads to tremendous economic losses in the pig industry worldwide. It is also associated with porcine respiratory disease complex (PRDC), which supports massive use of antibiotics. Although several modified live virus (MLV) and killed virus (KV) vaccines are on the market, PRRSV remains difficult to control in the field. The major aim of this thesis was to develop a new experimental inactivated PRRSV vaccine. The different processes to develop a vaccine are virus production, virus inactivation or attenuation and vaccine formulation. In this thesis, the virus production and the virus inactivation of PRRSV were optimized to develop an efficient KV vaccine. The first section of chapter 1 gives an introduction on PRRSV, more particular its history, classification, virus structure, genomic organization, viral proteins, replication cycle, clinical signs, pathogenesis, innate and adaptive immune response to PRRSV and the available vaccines. A second section of chapter 1 gives an overview of different viral inactivation procedures, such as cross-linkers (formaldehyde, glutaraldehyde and AT-2), denaturing agents (pH and temperature), irradiation (ultraviolet (UV) and gamma irradiation) and alkylating agents (binary ethyleneimine (BEI)), and their effect on viruses

Development of an experimental inactivated PRRSV vaccine that induces virus-neutralizing antibodies

Porcine reproductive and respiratory syndrome virus (PRRSV) can induce reproductive disorders and is involved in the porcine respiratory disease complex, causing tremendous economic losses to the swine industry. Inactivated PRRSV vaccines are preferred over attenuated vaccines because of their safety and flexibility towards emerging virus strains, but the efficacy of current inactivated PRRSV vaccines is questionable. In this study, experimental inactivated PRRSV vaccines were developed, based on two formerly optimized inactivation procedures: UV irradiation and treatment with binary ethylenimine (BEI). In a first experiment, it was shown that vaccination with UV- or BEI-inactivated virus in combination with Incomplete Freund's Adjuvant induced virus-specific antibodies and strongly primed the virus-neutralizing (VN) antibody response. Subsequently, the influence of adjuvants on the immunogenicity of neutralizing epitopes on the inactivated virus was investigated. It was shown that vaccination with BEI-inactivated virus in combination with a commercial oil-in-water adjuvant induced high titers (3.4 log(2)) of VN antibodies in 6/6 pigs, instead of only priming the neutralizing antibody response. After challenge, neutralizing antibody titers in these vaccinated animals rose to a mean value of 5.5 log(2), and the duration of the viremia was reduced to an average of 1 week. This study shows that, by the use of an optimized inactivation procedure and a suitable adjuvant, inactivated PRRSV vaccines can be developed that induce VN antibodies and offer partial protection upon challenge

Recent advances in the ultrasonic polar scan method for characterizing (degraded) fiber reinforced plastics

The ultrasonic polar scan (UPS) technique originated in the 1980's as a sophisticated method for inspecting composites. However, it is only in recent times that the true capabilities and strengths of the UPS methodology have been evidenced through experiment and simulation. Nowadays, the UPS method exists in different versions which led to several novel applications in the field of material inspection and characterization. This contribution gives an overview of our recent advances