Separation of proteins via continuous pH parametric pumping

This dissertation covers the separation of proteins via recuperative mode pH parametric pumping. Continuous pH parametric pumping separations using the model system haemoglobin and albumin on a CM-Sepharose cation exchanger have been experimentally and theoretically investigated. The pH parametric pumping system has a feed containing the protein mixture to be separated, introduced alternately to the top and bottom of the column. The top and bottom products are withdrawn from the apparatus during the bottom and top feed, respectively. Both equilibrium and nonequilibrium cases were considered, and theoretical results agreed with the experimental data. Buffer concentration, flow rate, reservoir displacement, and feed volumes have been found to be important in determining the pH parametric pumping performance. Many proteins are processed batchwise. Parametric pumping as described here offers the possibility of continuous processing, It is shown that under certain conditions, the pH parametric pumping is capable of achieving high separation. Moreover, the continuous process can be operated with a larger feed throughput

MEMS 411: Design of a wiffle ball pitching machine

This project designs a wiffle ball pitching machine that would demonstrate the Magus Effect to the audience in St. Louis Science Center. Primarily made out of wood, this design is portable and able to pitch wiffle balls both indoor and outdoor. With two spinning wheels whose maximum spinning rate is 5044 rpm, this design is able to pitch balls with topspin, backspin, and no spin, and the trajectory of the traveling balls can be recorded by naked eye. The highest recorded traveling velocity of the pitched ball is 67 mph. Several function that would facilitate the demo process are included in this design: accurate pitching and angle adjusting--it is able to pitch balls at an angle range of 0 degrees to 90 degrees and in the testing trial, 12/12 balls are able to hit a 20\u27 by 20\u27 target placed 20 feet away from the machine. There are several risks that a user might take notice of when using the machine: the spinning wheels might scratch a user\u27s hand when it gets too close; the wires connected to the motor would trip users; a user might be hit by a traveling wiffle ball; and if used improperly, a user may get electric shock. Warning signs are prepared on the device to prevent the such risks for happening

A survey of Venezuelan public opinion on the replacement of the Bolivar with either the U.S. dollar or the central bank of Venezuela with a currency board

Abstract. This paper describes the methodology and presents the results of a Datincorp survey on Venezuela’s economic crisis. The survey was carried out in March 2017. A majority of Venezuelans do not trust the Central Bank of Venezuela, and believe that immediate change is necessary.  A majority of Venezuelans also indicate that the implementation of dollarization or an orthodox currency board are not only the most desirable solutions in theory, but are also highly supported by Venezuelan public opinion.Keywords. Currency board, dollarization, monetary reform, Venezuela.JEL. E50; E42; P21

FedLE: Federated Learning Client Selection with Lifespan Extension for Edge IoT Networks

Federated learning (FL) is a distributed and privacy-preserving learning framework for predictive modeling with massive data generated at the edge by Internet of Things (IoT) devices. One major challenge preventing the wide adoption of FL in IoT is the pervasive power supply constraints of IoT devices due to the intensive energy consumption of battery-powered clients for local training and model updates. Low battery levels of clients eventually lead to their early dropouts from edge networks, loss of training data jeopardizing the performance of FL, and their availability to perform other designated tasks. In this paper, we propose FedLE, an energy-efficient client selection framework that enables lifespan extension of edge IoT networks. In FedLE, the clients first run for a minimum epoch to generate their local model update. The models are partially uploaded to the server for calculating similarities between each pair of clients. Clustering is performed against these client pairs to identify those with similar model distributions. In each round, low-powered clients have a lower probability of being selected, delaying the draining of their batteries. Empirical studies show that FedLE outperforms baselines on benchmark datasets and lasts more training rounds than FedAvg with battery power constraints.Comment: 6 pages, 6 figures, accepted to 2023 IEEE International Conference on Communications (ICC 2023

Can continental bogs with stand the pressure due to climate change?

Not all peatlands are alike. Theoretical and process based models suggest that ombrogenic, oligotrophic peatlands can withstand the pressures due to climate change because of the feedbacks among ecosystem production, decomposition and water storage. Although there have been many inductive explanations inferring from paleo-records, there is a lack of deductive empirical tests of the models predictions of these systems’ stability and there are few records of the changes in the net ecosystem carbon balance (NECB) of peatlands that are long enough to examine the dynamics of the NECB in relation to climate variability. Continuous measurements of all the components of the NECB and the associated general climatic and environmental conditions have been made at the Mer Bleue (MB) peatland, a large, 28 km2, 5 m deep, raised ombro-oligotrophic, shrub and Sphagnum covered bog, near Ottawa, Canada from May 1, 1998 until the present. The sixteen-year daily CO2, CH4, and DOC flux and NECB covers a wide range of variability in peatland water storage from very dry to very wet growing seasons. We used the MB data to test the extent of MB peatland’s stability and the strength of the underlying key feedback between the NECB and changes in water storage projected by the models. In 2007 we published a six-year (1999-2004) net ecosystem carbon balance (NECB) for MB of ∼22 ± 40 g C m-2 yr-1, but we have since recalculated the 1998-2004 NECB to be 32 ± 40 g C m-2 yr-1 based on a reanalyzed average NEP of 51 ± 41 g C m-2 yr-1. Over the same period the net loss of C via the CH4 and DOC fluxes were -4 ± 1 and -15 ± 3 g C m-2 yr-1. The 1998-2004 six-year MB average NECB is similar to the long-term C accumulation rate, estimated from MB peat cores, for the last 3,000 years. The post 2004 MB NEP has increased to an average of ∼96 ± 32 g C m-2 yr-1 largely to there being generally wetter growing seasons. The losses of C via DOC (18 ± 1 g C m-2 yr-1) and CH4 (7 ± 4 g C m-2 yr-1) while showing considerable year-to-year variability are not significantly different post 2004. Hence, the proportional loss of C as DOC and CH4 in the MB NECB is slightly less post-2004 than it was before 2004 though the cumulative errors preclude statistically differences. As a result the MB NECB has increased to 79 ± 29 g C m-2 yr-1 post 2004 yielding a 14 year contemporary NECB of 56 ± 36 g C m-2 yr-1, which is double the long-term accumulation rate of C. The variability in the annual NECB and growing season mean NEP for the MB bog can be explained (r2 = 0.35, p \u3c 0.01) by the variability in growing season water table depth. These results suggest the carbon balance – water table feedback is sufficient enough to create stability in continental bogs so they will withstand a considerable amount of climate change

Large-area, wide-angle, spectrally selective plasmonic absorber

A simple metamaterial-based wide-angle plasmonic absorber is introduced, fabricated, and experimentally characterized using angle-resolved infrared spectroscopy. The metamaterials are prepared by nano-imprint lithography, an attractive low-cost technology for making large-area samples. The matching of the metamaterial's impedance to that of vacuum is responsible for the observed spectrally selective "perfect" absorption of infrared light. The impedance is theoretically calculated in the single-resonance approximation, and the responsible resonance is identified as a short-range surface plasmon. The spectral position of the absorption peak (which is as high as 95%) is experimentally shown to be controlled by the metamaterial's dimensions. The persistence of "perfect" absorption with variable metamaterial parameters is theoretically explained. The wide-angle nature of the absorber can be utilized for sub-diffraction-scale infrared pixels exhibiting spectrally selective absorption/emissivity.Comment: 7 pages, 6 figures, submitted to Phys. Rev.