Bridging the gap: rewritable electronics using real-time light-induced dielectrophoresis on lithium niobate

In the context of micro-electronics, the real-time manipulation and placement of components using optics alone promises a route towards increasingly dynamic systems, where the geometry and function of the device is not fixed at the point of fabrication. Here, we demonstrate physically reconfigurable circuitry through light-induced dielectrophoresis on lithium niobate. Using virtual electrodes, patterned by light, to trap, move, and chain individual micro-solder-beads in real-time via dielectrophoresis, we demonstrate rewritable electrical contacts which can make electrical connections between surface-bound components. The completed micro-solder-bead bridges were found to have relatively low resistances that were not solely dominated by the number of interfaces, or the number of discrete beads, in the connection. Significantly, these connections are formed without any melting/fusing of the beads, a key feature of this technique that enables reconfigurability. Requiring only a low-power (~3.5 mW) laser source to activate, and without the need for external power supply or signal generation, the all-optical simplicity of virtual-electrodes may prove significant for the future development of reconfigurable electronic systems

Emergency seed aid in Kenya: some case study insights on lessons learned during the 1990s

This article reviews the effectiveness of seed–aid distributions in Kenya during the 1990s. It analyses the internal process and effects, i.e. the performance of the aid itself as well as the external process and effects, i.e. how seed–aid intervention affected farmers’ broader agricultural management strategies. During the drought emergency of 1997, Kenyan farmers favourably judged many of the immediate seed–aid features such as crop and variety appropriateness and seed quality — even through the overarching goals of the seed assistance were muddled, ranging from assistance to the poor, to generalised gift–giving to stimulating progressive farming practice. However, the longer term analyses, drawn from recollections of a decade of relief activity, showed no concrete evidence that seed aid, per se, had strengthened their farming systems, nor that those who have received it once were less likely to receive it again. Thus, while seed aid has been promoted to lessen the effects of an ‘acute’ stress, drought, Kenyan farmers, in practice, have been experiencing much wider, ‘chronic’ seed system problems. This article ends by exploring this distinction between acute and chronic seed system stress and suggests a range of interventions appropriate to each

Seed systems smallholder farmers use

Seed can be an important entry point for promoting productivity, nutrition and resilience among smallholder farmers. While investments have primarily focused on strengthening the formal sector, this article documents the degree to which the informal sector remains the core for seed acquisition, especially in Africa. Conclusions drawn from a uniquely comprehensive data set, 9660 observations across six countries and covering 40 crops, show that farmers access 90.2 % of their seed from informal systems with 50.9 % of that deriving from local markets. Further, 55 % of seed is paid for by cash, indicating that smallholders are already making important investments in this arena. Targeted interventions are proposed for rendering formal and informal seed sector more smallholder-responsive and for scaling up positive impacts

Treating patients with medically resistant epilepsy.

Recent evidence suggests that medically resistant epilepsy can be identified if seizures persist despite adequate doses of 2 appropriate first-line antiepileptic drugs (AEDs). Patients with medically resistant epilepsy should have their seizures carefully characterized in order to confirm their diagnosis, select treatment, and assist in determining prognosis. Patients should be counseled about factors that aggravate epilepsy and the importance of adhering to treatments. Physicians should carefully inquire about side effects and alter therapy to eliminate or minimize these symptoms. Uncontrolled seizures cause injuries, disability, and increased mortality, so surgery should be considered as soon as seizures are proven to be medically resistant. Patients with incomplete response to AEDs and who are not surgical candidates may benefit from additional medication trials or from palliative nonmedical therapies, such as vagal nerve stimulation