Effect of knocking down the insulin receptor on mouse rod responses.

Previous experiments have shown that the insulin receptor (IR) is expressed in mammalian rods and contributes to the protection of photoreceptors during bright-light exposure. The role of the insulin receptor in the production of the light response is however unknown. We have used suction-electrode recording to examine the responses of rods after conditionally knocking down the insulin receptor. Our results show that these IR knock-down rods have an accelerated decay of the light response and a small decrease in sensitivity by comparison to littermate WT rods. Our results indicate that the insulin receptor may have some role in controlling the rate of rod response decay, but they exclude a major role of the insulin receptor pathway in phototransduction

Adoption of improved agricultural practices: Learning from off-season vegetable production in Nepal

This study examines factors that appear to contribute to farmers’ adoption and discontinuation of poly house technology for off-season vegetable production. We collected cross-sectional survey data from a sample of 151 households in Kaski district, Nepal during October 2018. The data are analyzed using Heckman’s two stage sample selection model. The study reveals that the family members report being engaged in nonfarm sector that there is an increased probability of discontinuation of poly house technology. Farmers may be diverting their labor towards nonfarm activities that result in higher returns to labor and different risks. At the same time, the results indicate that farmers who did not receive training on vegetable production were more likely to discontinue poly house technology. It was also found that increasing farmers’ engagement with marketing activities increased the likelihood of farmers to continue poly house technology and increase household income. The provision of continued technical support (e.g., training), input supply (e.g., seeds, fertilizers) and market information are essential to sustain the adopted technologies. The study sheds light on the sustainability of technology adoption by underpinning the importance of extension services for longer-term adoption. We believe that the combined effect of various technologies would be associated with sustained adoption of the improved off-season technologies. This provides a new direction to operationalize farmer-oriented policies in agricultural extension and helps in devising programs for sustained adoption of technology

Negative Stress Margins - Are They Real?

Advances in modeling and simulation, new finite element software, modeling engines and powerful computers are providing opportunities to interrogate designs in a very different manner and in a more detailed approach than ever before. Margins of safety are also often evaluated using local stresses for various design concepts and design parameters quickly once analysis models are defined and developed. This paper suggests that not all the negative margins of safety evaluated are real. The structural areas where negative margins are frequently encountered are often near stress concentrations, point loads and load discontinuities, near locations of stress singularities, in areas having large gradients but with insufficient mesh density, in areas with modeling issues and modeling errors, and in areas with connections and interfaces, in two-dimensional (2D) and three-dimensional (3D) transitions, bolts and bolt modeling, and boundary conditions. Now, more than ever, structural analysts need to examine and interrogate their analysis results and perform basic sanity checks to determine if these negative margins are real

Needs and challenges in model testing of wave and tidal energy device

Evaluation of the viability of wave and tidal energy converters represent the main challenge for marine energy developers and government agencies. Although the concept of wave energy conversion is very intuitive, its performance evaluation is complicated by different factors including evaluation of efficiency, components performance and maintenance costs. These factors do not scale up directly from lab experiments. Testing at 1/100 or smaller ratios cannot resolve critical details or satisfy required dynamic similarities. Full-scale testing is expensive. Additionally, varying the designs may not be an option. This implies a need for testing at larger scales. In controlled tests at 1/50 or larger scales, WEC responses can be determined to the point where they can be scaled up and modes of failure can be assessed. This presentation discusses dynamic similarity, scaling laws and how these can be applied to wave and tidal energy devices. Test methodologies, standards and specialized instrumentation, understanding and interpretation of results will also be discussed. The presentation is based on knowledge gained from tests conducted on numerous scale model hull forms and marine platforms in the towing/wave tank of the Davidson Laboratory that have resulted in military full-scale prototypes and commercial systems. Please click Additional Files below to see the full abstract

The effect of core-shell engineering on the energy product of magnetic nanometals.

Solution-based growth of magnetic FePt-FeCo (core-shell) nanoparticles with a controllable shell thickness has been demonstrated. The transition from spin canting to exchange coupling of FePt-FeCo core-shell nanostructures leads to a 28% increase in the coercivity (12.8 KOe) and a two-fold enhancement in the energy product (9.11 MGOe)

Dust trapping in inviscid vortex pairs

The motion of tiny heavy particles transported in a co-rotating vortex pair, with or without particle inertia and sedimentation, is investigated. The dynamics of non-inertial sedimenting particles is shown to be chaotic, under the combined effect of gravity and of the circular displacement of the vortices. This phenomenon is very sensitive to particle inertia, if any. By using nearly hamiltonian dynamical system theory for the particle motion equation written in the rotating reference frame, one can show that small inertia terms of the particle motion equation strongly modify the Melnikov function of the homoclinic trajectories and heteroclinic cycles of the unperturbed system, as soon as the particle response time is of the order of the settling time (Froude number of order unity). The critical Froude number above which chaotic motion vanishes and a regular centrifugation takes place is obtained from this Melnikov analysis and compared to numerical simulations. Particles with a finite inertia, and in the absence of gravity, are not necessarily centrifugated away from the vortex system. Indeed, these particles can have various equilibrium positions in the rotating reference frame, like the Lagrange points of celestial mechanics, according to whether their Stokes number is smaller or larger than some critical value. An analytical stability analysis reveals that two of these points are stable attracting points, so that permanent trapping can occur for inertial particles injected in an isolated co-rotating vortex pair. Particle trapping is observed to persist when viscosity, and therefore vortex coalescence, is taken into account. Numerical experiments at large but finite Reynolds number show that particles can indeed be trapped temporarily during vortex roll-up, and are eventually centrifugated away once vortex coalescence occurs.Comment: 7 figure

Flash sintering of armor materials: Challenges and opportunities

Flash sintering has been found to enable rapid densification of a wide range of ceramics at lower processing temperatures and shorter times than conventional sintering. This is of particular interest for materials that are difficult to conventionally sinter, including those used in ceramic armor systems, such as B4C, SiC, and B6O. However, the driving mechanisms behind flash sintering are still hotly debated, and the interactions between the processing parameters and the materials being sintered are only in the early stages of being explored. Furthermore, there has been little documented effort to flash sinter these materials and characterize the process. The Army Research Laboratory strategy for research on flash and field-enhanced sintering of ceramics is described, with particular focus on the challenges and opportunities for sintering boron carbide and other relevant armor materials. The design of a scalable flash sintering apparatus and the observed effects of various process parameters such as contact mechanism, atmosphere, current/voltage profile, and part shape as they relate to flash and densification behavior are discussed. This research was supported in part by an appointment to the Postgraduate Research Participation Program at the U.S. Army Research Laboratory administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and USARL. Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-16-2-0050-P0003. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. The research reported in this document was performed in connection with contract/instrument W911QX-16-D-0014 with the U.S. Army Research Laboratory. The views and conclusions contained in this document are those of SURVICE Engineering and the U.S. Army Research Laboratory. Citation of manufacturer\u27s or trade names does not constitute an official endorsement or approval of the use thereof. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation hereon