Balanced electronic detection of displacement in nanoelectromechanical systems

We describe a broadband radio frequency balanced bridge technique for electronic detection of displacement in nanoelectromechanical systems (NEMS). With its two-port actuation-detection configuration, this approach generates a background-nulled electromotive force in a dc magnetic field that is proportional to the displacement of the NEMS resonator. We demonstrate the effectiveness of the technique by detecting small impedance changes originating from NEMS electromechanical resonances that are accompanied by large static background impedances at very high frequencies. This technique allows the study of important experimental systems such as doped semiconductor NEMS and may provide benefits to other high frequency displacement transduction circuits

Standards compliance as an alternative learning opportunity under globalization in Latin America

globalization, technological infrastructures, certification, capability, Latin America, Chile

Terahertz wave generation from a dc-biased multimode laser

We present results achieved in the generation of terahertz wave by a semiconductor laser. It is a Fabry–Pérot based device with shallow grooves implemented on its p-side to engineer the longitudinal mode spectrum. The laser is dc-biased and temperature controlled at 298 K. The main two modes are separated by 3 nm at 1550 nm with a side-mode-suppression ratio of 25 dB. Using a frequency resolved optical gating, evidence of mode beating at 373 GHz is observed. With a bolometer interfaced to a Fourier transform interferometer, the second harmonic signal is measured at 690 GHz

Minnesota Extension's Mixed Regional/County Model: Greater Impacts Follows Changes in Structure

The Cooperative Extension Service has as its mission helping the public use the research generated at land-grant universities. Since 1914, most states have used a county-based Extension model, with educators in every county and campus-based faculty supporting local educational efforts. This paper outlines why and how the Minnesota Extension Service has replaced this model with a mixed regional/county model, the major features of the new delivery model and the employment consequences of the shift as well as the non-financial advantages of the new model. The structural changes in Minnesota are of interest to Extension stakeholders in other states who are facing similar challenges and want to learn more about the benefits and costs of Minnesota's new model. Within Minnesota the public is beginning to ask a much more important question: What are the impacts of the programs being delivered? Structural change is only valuable if it results in increased programming and greater impacts than would have happened without the change. Although this paper starts to outline some of the changes in program impact, the bulk of that discussion will be reserved for later papers.Teaching/Communication/Extension/Profession,

Effect of stocking density of fish on water quality and growth performance of European Carp and leafy vegetables in a low-tech aquaponic system

Aquaponics (AP) is a semi-closed system of food production that combines aquaculture and hydroponics and represents a new agricultural system integrating producers and consumers. The aim of this study was to test the effect of stocking densities (APL, 2.5 kg m-3; APH, 4.6 kg m-3) on water quality, growth performance of the European Carp (Cyprinus carpio L.), and yield of leafy vegetables (catalogna, lettuce, and Swiss Chard) in a low-technology AP pilot system compared to a hydroponic cultivation. The AP daily consumption of water due to evapotranspiration was not different among treatments with an average value of 8.2 L d-1, equal to 1.37% of the total water content of the system. Dissolved oxygen was significantly (p < 0.05) different among treatments with the lowest median value recorded with the highest stocking density of fish (5.6 mg L-1) and the highest median value in the hydroponic control (8.7 mg L-1). Marketable yield of the vegetables was significantly different among treatments with the highest production in the hydroponic control for catalogna (1.2 kg m-2) and in the APL treatment for Swiss Chard (5.3 kg m-2). The yield of lettuce did not differ significantly between hydroponic control and APL system (4.0 kg m-2 on average). The lowest production of vegetables was obtained in the APH system. The final weight (515 g vs. 413 g for APL and APH, respectively), specific growth rate (0.79% d-1 vs. 0.68% d-1), and feed conversion (1.55 vs. 1.86) of European Carp decreased when stocking density increased, whereas total yield of biomass was higher in the APH system (4.45 kg m-3 vs. 6.88 kg m-3). A low mortality (3% on average) was observed in both AP treatments. Overall, the results showed that a low initial stocking density at 2.5 kg m-3 improved the production of European Carp and of leafy vegetables by maintaining a better water quality in the tested AP system

Product bundling in global ocean transportation

There are over 20 'components' in an international door-to-door transportation, ranging from warehousing and distribution, to forwarding, documentation, transportation, customs clearance, etc..As tariffs in ocean transportation tend to converge due to competition and service homogenization, carriers, in competition with third party logistics service providers, strive to integrate door-to-door services under their control. In doing so, and among others, they invest heavily in logistics rather than ships that can nowadays be easily chartered in from institutional investors.Integration efforts however have been met with varying degrees of success in the face of skeptical and suspicious shippers requiring cost break down and more transparency. With the use of game theory, this paper attempts to develop winning service bundling strategies for ocean carriers, i.e. global supply chain solutions under all-in prices. Preliminary results show that, under certain conditions, bundling can be an equilibrium strategy for one or more carriers, and despite leveraging around captive liner services and potentially enhanced profits, bundling does not necessarily lead to a loss in social welfare.bundling;integrated logistics;liner shipping;vertical integration