Traditional Healing in the Contemporary Life of the Antanosy People of Madagascar

Traditional healing among the Antanosy people of southeastern Madagascar requires medicinal plants used by highly trained ombiasa (shamen). Given the influence of globalization, we hypothesized diminishing reliance on traditional medicine among the Antanosy. We studied a community and its healer’s views on the current value of traditional medicine compared to past decades and relationships between western medicine and traditional healing. Methods included interviews with ombiasa community members and participant observation. Traditional healing remained important. The numbers of ombiasa and apprentices were stable. Traditional and western medicine were complementary, providing the advantages of both without sacrificing traditional culture. Ombiasa linked the living to the ancestors who strongly influence contemporary Antanosy life. Without the ombiasa and their traditional knowledge of medicinal plants, people’s link to their ancestors, and the ancestors’ influence on the future, would disappear along with the plants essential to traditional healing

Developing a partcipatory approach to seed production and varietal selection

The performance of UK winter wheat varieties was tested under organic conditions involving farmer participation. Three breadmaking varieties (Hereward, Solstice and Xi19) and their mixture (1:1:1) were grown at 19 UK farms in 2003/04 and 2004/05. The variability of productivity on organic farms was illustrated with more variation among farm sites than among varieties. Seed health was generally high over all sites. Although the trials were successful, more time was needed at project initiation to improve farmer involvement. Some farmers expected more researcher visits, and were reticent about assessing the trials themselves. In contrast, some participants valued the variety performance data on their farms particularly when related to that of other growers. The balance between the goals of the researchers relative to the farmers needs to be defined at project initiation

Superconducting coplanar waveguide resonators for low temperature pulsed electron spin resonance spectroscopy

We discuss the design and implementation of thin film superconducting coplanar waveguide micro- resonators for pulsed ESR experiments. The performance of the resonators with P doped Si epilayer samples is compared to waveguide resonators under equivalent conditions. The high achievable filling factor even for small sized samples and the relatively high Q-factor result in a sensitivity that is superior to that of conventional waveguide resonators, in particular to spins close to the sample surface. The peak microwave power is on the order of a few microwatts, which is compatible with measurements at ultra low temperatures. We also discuss the effect of the nonuniform microwave magnetic field on the Hahn echo power dependence

Fluorescent Silicon Clusters and Nanoparticles

The fluorescence of silicon clusters is reviewed. Atomic clusters of silicon have been at the focus of research for several decades because of the relevance of size effects for material properties, the importance of silicon in electronics and the potential applications in bio-medicine. To date numerous examples of nanostructured forms of fluorescent silicon have been reported. This article introduces the principles and underlying concepts relevant for fluorescence of nanostructured silicon such as excitation, energy relaxation, radiative and non-radiative decay pathways and surface passivation. Experimental methods for the production of silicon clusters are presented. The geometric and electronic properties are reviewed and the implications for the ability to emit fluorescence are discussed. Free and pure silicon clusters produced in molecular beams appear to have properties that are unfavourable for light emission. However, when passivated or embedded in a suitable host, they may emit fluorescence. The current available data show that both quantum confinement and localised transitions, often at the surface, are responsible for fluorescence. By building silicon clusters atom by atom, and by embedding them in shells atom by atom, new insights into the microscopic origins of fluorescence from nanoscale silicon can be expected.Comment: 5 figures, chapter in "Silicon Nanomaterials Sourcebook", editor Klaus D. Sattler, CRC Press, August 201

Moho topography beneath the Corinth Rift area (Greece) from inversion of gravity data

International audienceOur aim is to understand better the rifting process by imaging the Moho depth variation beneath Corinth and Evvia. We present here the results of a gravity inversion analysis in the region of the Corinth and Evvia rift system, and compare them to those obtained independently from teleseismic tomography and receiver function analyses. The results of these different studies appear to be consistent and show (1) a 10 km crustal thickening in the western part of the area beneath the Hellenides mountains, (2) NW–SE-trending periodic crustal thinning, and (3) a maximum crustal thinning north of the Gulf of Corinth. This 4 km thinning is unlikely to be the result of the rifting alone, which seems to have been reactivated since only 1 Ma. We propose here a geodynamical scenario in two major steps to explain the evolution of Corinth area. Aegean Miocene extension involving boudinage resulted in periodic crustal thinning, consistent with observations. These lithospheric instabilities could have favoured rupture initiation in particular areas, especially near the city of Corinth. Then, the reactivation of the Corinth Rift extension, 1 Myr ago, led to westward rift propagation. The offset observed between the maximum crustal thinning and the Gulf of Corinth could be accommodated by a low-angle normal fault at about 10–15 km depth. The Corinth Rift is thus asymmetrical and was initiated in places of crustal weakness due to Miocene lithospheric instabilities

Electron Paramagnetic Resonance of Boron Acceptors in Isotopically Purified Silicon

The electron paramagnetic resonance (EPR) linewidths of B acceptors in Si are found to reduce dramatically in isotopically purified 28Si single crystals. Moreover, extremely narrow substructures in the EPR spectra are visible corresponding to either an enhancement or a reduction of the absorbed microwave on resonance. The origin of the substructures is attributed to a combination of simultaneous double excitation and spin relaxation in the four level spin system of the acceptors. A spin population model is developed which qualitatively describes the experimental results.Comment: 4 pages, 3 figure

Valley splitting of Si/SiGe heterostructures in tilted magnetic fields

We have investigated the valley splitting of two-dimensional electrons in high quality Si/Si$_{1-x}$Ge$_x$ heterostructures under tilted magnetic fields. For all the samples in our study, the valley splitting at filling factor $\nu=3$ ($\Delta_3$) is significantly different before and after the coincidence angle, at which energy levels cross at the Fermi level. On both sides of the coincidence, a linear density dependence of $\Delta_3$ on the electron density was observed, while the slope of these two configurations differs by more than a factor of two. We argue that screening of the Coulomb interaction from the low-lying filled levels, which also explains the observed spin-dependent resistivity, is responsible for the large difference of $\Delta_3$ before and after the coincidence.Comment: REVTEX 4 pages, 4 figure

Comparison of Birkeland current observations during two magnetic cloud events with MHD simulations

Low altitude field-aligned current densities ob- tained from global magnetospheric simulations are compared with two-dimensional distributions of Birkeland currents at the topside ionosphere derived from magnetic field observa- tions by the constellation of Iridium satellites. We present the analysis of two magnetic cloud events, 17–19 August 2003 and 19–21 March 2001, where the interplanetary magnetic field (IMF) rotates slowly (∼10◦/h) to avoid time-aliasing in the magnetic perturbations used to calculate the Birkeland currents. In the August 2003 event the IMF rotates from southward to northward while maintaining a negative IMF By during much of the interval. During the March 2001 event the IMF direction varies from dawnward to southward to duskward. We find that the distributions of the Birkeland current densities in the simulations agree qualitatively with the observations for northward IMF. For southward IMF, the dayside Region-1 currents are reproduced in the simu- ◦ the ionospheric grids in the simulations and the observations is shown to have only secondary effect on the magnitudes of the Birkeland currents. The electric potentials in the simu- lation for southward IMF periods are twice as large as those obtained from measurements of the plasma drift velocities by DMSP, implying that the reconnection rates in the simulation are too large. Keywords. Ionosphere (Electric fields and currents; Ionosphere-magnetosphere interactions; Modeling and forecasting) 1 Introduction Global magnetohydrodynamic (MHD) models are the most comprehensive numerical tool for studying the coupling of energy and momentum of the solar wind into the Earth’s magnetosphere and ionosphere. A particular advantage of global MHD simulations is the ability to provide continu- ous temporal and spatial coverage of key physical parame- ters over the entire simulation volume. For this reason, MHD simulations have become one of the principal tools for study- ing space weather events such as the interaction of the Earth’s magnetosphere with coronal mass ejections (CMEs) (Ridley et al., 2002) as well as magnetic storms (Slinker et al., 1998; Goodrich et al., 1998) and substorms (Lyon et al., 1998; Lopez et al., 1998; Wiltberger et al., 2000). Since the simula- tion results are frequently used to interpret physical processes in the magnetosphere–ionosphere system, assessing their ac- curacy by comparison with observations is an important task. A number of such studies have been carried out in the past us- ing space-based (Frank et al., 1995; Raeder et al., 1997) and ground-based observations (Ridley et al., 2001), or a com- bination thereof (Fedder et al., 1998; Slinker et al., 1999). However, interpreting the discrepancies between model and observations is not straightforward because the observational lation, but appear on average 5 served location, while the nightside Region-1 currents and the Region-2 currents are largely under-represented. Com- parison of the observed and simulated Birkeland current dis- tributions, which are intimately related to the plasma drifts at the ionosphere, shows that the ionospheric convection pat- tern in the MHD model and its dependence on the IMF ori- entation is essentially correct. The Birkeland total currents in the simulations are about a factor of 2 larger than observed during southward IMF. For Bz\u3e0 the disparity in the total current is reduced and the simulations for purely northward IMF agree with the observations to within 10%. The dispar- ities in the magnitudes of the Birkeland currents between the observations and the simulation results are a combined effect of the simulation overestimating the ionospheric electric field and of the Iridium fits underestimating the magnetic pertur- bations