8,822 research outputs found
Heat release by controlled continuous-time Markov jump processes
We derive the equations governing the protocols minimizing the heat released
by a continuous-time Markov jump process on a one-dimensional countable state
space during a transition between assigned initial and final probability
distributions in a finite time horizon. In particular, we identify the
hypotheses on the transition rates under which the optimal control strategy and
the probability distribution of the Markov jump problem obey a system of
differential equations of Hamilton-Bellman-Jacobi-type. As the state-space mesh
tends to zero, these equations converge to those satisfied by the diffusion
process minimizing the heat released in the Langevin formulation of the same
problem. We also show that in full analogy with the continuum case, heat
minimization is equivalent to entropy production minimization. Thus, our
results may be interpreted as a refined version of the second law of
thermodynamics.Comment: final version, section 2.1 revised, 26 pages, 3 figure
Stand-alone wearable system for ubiquitous real-time monitoring of muscle activation potentials
Wearable technology is attracting most attention in healthcare for the acquisition of physiological signals. We propose a stand-alone wearable surface ElectroMyoGraphy (sEMG) system for monitoring the muscle activity in real time. With respect to other wearable sEMG devices, the proposed system includes circuits for detecting the muscle activation potentials and it embeds the complete real-time data processing, without using any external device. The system is optimized with respect to power consumption, with a measured battery life that allows for monitoring the activity during the day. Thanks to its compactness and energy autonomy, it can be used outdoor and it provides a pathway to valuable diagnostic data sets for patients during their own day-life. Our system has performances that are comparable to state-of-art wired equipment in the detection of muscle contractions with the advantage of being wearable, compact, and ubiquitous
Crossing the Bridge of Size: Reaching a Deal at Nice
The Intergovernmental Conference which should conclude at Nice in December 2000 deals with issues of institutional reform which must be resolved before proceeding with enlargement. There are four main questions. Should all countries be able to name a Member of the European Commission, or should the number of Commissioners be ‘capped’ at a number lower than the number of Member States? How should the weighting of Member States’ votes in the Council be adjusted to ensure that winning coalitions under qualified-majority voting represent an adequate proportion of the total EU population – as well as to ‘compensate’ those five Member States which lose their second Commissioner? How far should qualified-majority voting be extended? Should the conditions for ‘closer cooperation’ be relaxed to make it easier to press ahead with integration in particular areas without the participation of all Member States? A deal must be reached at Nice, but the IGC has revealed serious differences between the Member States. There is likely to be an agreement: for one Commissioner per Member State, probably with an internal hierarchy; a significant reweighting of votes in favour of the big Member States; a moderate extension of qualified-majority voting; and at least the removal of the veto regarding closer cooperation. Yet relative size has emerged as a source of frictions and concerns about long-term solidarity. The big countries fear being tied down. The smaller ones have long-term concerns about being dominated or absorbed, as well as presentational problems. If all the results of the IGC are seen as concessions to the large countries, it will be hard to sell the Nice Treaty at home – and Denmark has again shown that people can say No. Too much intergovernmentalism is not the answer. The Community institutions cannot do everything, but they have played an essential role in overcoming fears about relative power. They need to be renewed, not replaced
Differentiation of human induced pluripotent stem cells into cortical neural stem cells
Efficient and effective methods for converting human induced pluripotent stem cells into differentiated derivatives are critical for performing robust, large-scale studies of development and disease modelling, and for providing a source of cells for regenerative medicine. Here, we describe a 14-day neural differentiation protocol which allows for the scalable, simultaneous differentiation of multiple iPSC lines into cortical neural stem cells We currently employ this protocol to differentiate and compare sets of engineered iPSC lines carrying loss of function alleles in developmental disorder associated genes, alongside isogenic wildtype controls. Using RNA sequencing (RNA-Seq), we can examine the changes in gene expression brought about by each disease gene knockout, to determine its impact on neural development and explore mechanisms of disease. The 10-day Neural Induction period uses the well established dual-SMAD inhibition approach combined with Wnt/beta-Catenin inhibition to selectively induce formation of cortical NSCs. This is followed by a 4-day Neural Maintenance period facilitating NSC expansion and rosette formation, and NSC cryopreservation. We also describe methods for thawing and passaging the cryopreserved NSCs, which are useful in confirming their viability for further culture. Routine implementation of immunocytochemistry Quality Control confirms the presence of PAX6-positive and/or FOXG1-positive NSCs and the absence of OCT4-positive iPSCs after differentiation. RNA-Seq, flow cytometry, immunocytochemistry (ICC) and RT-qPCR provide additional confirmation of robust presence of NSC markers in the differentiated cells. The broader utility and application of our protocol is demonstrated by the successful differentiation of wildtype iPSC lines from five additional independent donors. This paper thereby describes an efficient method for the production of large numbers of high purity cortical NSCs, which are widely applicable for downstream research into developmental mechanisms, further differentiation into postmitotic cortical neurons, or other applications such as large-scale drug screening experiments.Peer reviewe
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Pricing Carbon for Electricity Generation: National and International Dimensions
In this paper, which forms a chapter in the forthcoming Book âÂÂDelivering a Low Carbon Electricity System: Technologies, Economics and PolicyâÂÂ, Grubb and Newbery examine how carbon for electricity generation should be priced. They begin by suggesting that it is not clear what the correct price of carbon is, but that it spans the whole range of economically plausible prices. They then go on to discuss the theoretical merits of taxes versus quotas, concluding that theoretically a stable tax would best reflect the true social cost of emissions, which should not change with market conditions. They then go to evaluate the EU Emissions Trading Scheme where allowances for the emission of CO2 are traded (EUAs). The price signals offered by the scheme in its first trading period have been very unsatisfactory with high variability and the price trending down towards very low levels as it has become clear that governments were much too generous in their initial allocation of quotas. What is needed is a stable investment environment for low carbon generation investments. They discuss a number of policy options to achieve this: long period commitments on quotas; allowing unconstrained banking and borrowing of EUAs over multiple periods; long term price declarations to be used in allocation auctions; government issued contracts for differences on the future carbon price; or simply to issue low-carbon electricity contracts. The authors conclude with a discussion of the scope for international agreements on carbon emissions reduction. They conclude that imperfect though it is the EU ETS is a good place to start to link up emerging trading regimes, and that quota systems have more of a chance of commanding international agreement at least initially. However any international climate change agreement will be difficult to establish
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