We assess the impact of the ECB's unconventional monetary policy (UMP) on the wealth distribution of households in ten euro area countries. For this purpose, we estimate the effects of an ECB balance sheet expansion on financial asset and housing prices by means of vector autoregressions. We then use the estimates to carry out micro simulations based on data from the Household Finance and Consumption Survey (HFCS). We find that the overall effect of UMP on the net wealth distribution of households differs depending on which wealth inequality indicators we use. There is an inequality-increasing effect for the majority of the countries under review when we use wealth inequality indicators that are sensitive to changes at the tails of the wealth distribution. The effect is more equalizing when we base our assessment on the Gini coefficient. It is also important to note that one-third of the households in our sample does not hold financial or housing wealth and is thus not directly affected by UMP measures via the asset price channel. / Series: Department of Economics Working Paper Series

To assist in the development of mechanical structures which are subjected to dynamic loads, structural dynamic testing, using a test rig loaded by servo-hydraulic actuators to reproduce operational measured responses in the laboratory, may form an essential element of the development process. The input loads acting on the structure under operational conditions can in most cases not be measured directly, and instead the structural dynamic responses to these loads are recorded. The input forcing functions then need to be determined to effect a simulation of the operational conditions. With this work, a time domain based testing system has been developed to enable the reproduction of service-acquired dynamic responses on any actual full scale structure in the laboratory, taking into account the full multiple axis dynamics of the system. The system is able to determine the input forcing functions in such a way that, when applied to the teststructure, an accurate reproduction of the in-service measured responses are reproduced on the computer controlled laboratory test rig. The test structure is instrumented with suitable transducers which are used to record the structural dynamic response under operational conditions. The test structure is thereafter installed in a servo-hydraulic actuator test rig in the laboratory. The test rig is excited with synthetic random inputs while simultaneously recording the responses to these inputs. Using the experimental input-output data, a dynamic model of the test system is found by using parametric dynamic system identification techniques. By using the service aquired vibration responses together with the dynamic model, the system inputs may be determined. A series of iterations around this first approximation finally provides a high degree of accuracy in the simulation. To prove the integrity of the developed system, it has been applied to a number of case studies using a variety of different engineering structures, and very accurate results were achieved. / Thesis (PhD)--University of Pretoria, 1993. / tm2015 / Mechanical and Aeronautical Engineering / PhD / Unrestricted

Seeds of the root parasitic plants of the genus Orobanche germinate specifically in response to host-derived germination signals, which enables parasites to detect and attack preferred hosts. The best characterized class of germination stimulants is the strigolactones (SLs), although some species respond to non-SL compounds, such as dehydrocostus lactone (DCL). Recent work indicates that SLs are perceived by members of the KARRIKIN-INSENSITIVE2 (KAI2) gene family, and suggests that within parasitic Orobanchaceae the KAI2 genes have undergone duplication and specialization. The "diverged" clade of these genes, termed KAI2d, has been shown to bind SL germination stimulants in model system assays, but the precise role for KAI2d in regulating germination specificity in a parasitic plant has not been demonstrated. To address this issue, we used genetic and genomic approaches involving two closely related species, Orobanche cernua and O. cumana, which differ primarily in host range and stimulant preference. Orobanche cernua parasitizes tomato (and other Solanaceous crops) and responds to orobanchol, the major SL from tomato roots, whereas O. cumana specifically parasitizes sunflower and responds to DCL. Crosses between O. cernua and O. cumana produced hybrid populations that segregate for stimulant specificity, creating a tractable genetic system. Orobanche cernua contains four KAI2d genes (numbered OrceKAI2d1-4), while O. cumana contains six genes (OrcuKAI2d1-6). The DNA from 94 F2 hybrids was genotyped to identify the KAI2d gene composition and these were correlated with germination phenotype. The pattern of segregation indicated that the KAI2d genes are linked, but pointed to OrceKAI2d2 as a likely orobanchol receptor. Response to DCL was associated with inheritance of all O. cumana KAI2d genes together. Each KAI2d gene was expressed in the Arabidopsis thaliana kai2 mutant background and tested for ability to recover the mutant phenotype when exposed to SLs (including orobanchol, 5-deoxystrigol and GR24) or DCL. One O. cernua gene, OrceKAI2d2, responded to all SLs, but not DCL in this system. No DCL-specific KAI2 genes were identified. In summary, we have identified the likely SL receptor in O. cernua, and show evidence that the DCL receptor is either not a KAI2d protein, or uses KAI2d in combination with other signaling pathway components. / Ph. D. / The mechanisms by which parasitic plants of the family Orobanchaceae detect their hosts is a long-standing mystery in plant science. For over half a century it has been known that seeds of parasitic plants will lie dormant until they detect a host-derived germination stimulant. Upon perception of an appropriate germination stimulant, the parasite seeds will send out a radical that has approximately 72 hours to reach a host root before the limited nutrients within the seed are exhausted. The practical impact of this plant signaling regulation is profound, as the parasites in this family include some of the most destructive weeds in the world, including broomrapes (Orobanche and Phelipanche species) and witchweeds (Striga species). Scientists have sought to understand the signaling mechanisms in order to produce crop plants that don’t produce/exude the signal or to create chemicals that can mimic stimulants and artificially trigger parasite seed germination. Our goal was to further the understanding of the parasite germination mechanism by determining the genes involved in parasite host specificity in Orobanche, of which most members germinate in response to strigolactones (SLs). Recent work indicates that SLs are perceived by members of the KARRIKIN-INSENSITIVE2 (KAI2) gene family and suggests that within parasitic Orobanchaceae the KAI2 genes have undergone duplication and specialization. The “diverged” clade of these genes, termed KAI2d, has been shown to bind SL germination stimulants in model system assays, but the precise role for KAI2d in regulating germination specificity in a parasitic plant has not been demonstrated. To this end we used two closely related species that differ in their germination stimulant and host preferences. Orobanche cernua which like most members of Orobanchaceae responds to a SL, and O. cumana which has switched to responding to a novel germination stimulant, dehydrocostus lactone (DCL). Through genetic and genomic studies of these two species, we demonstrated that one O. cernua gene, OrceKAI2d2, responded to all SLs, but not DCL in this system. No DCL-specific KAI2 genes were identified. In summary, we have identified the likely SL receptor in O. cernua, and show evidence that the DCL receptor is either not a KAI2d protein, or uses KAI2d in combination with other signaling pathway components.