The Study of Foreign Policy: A Perspective

The study of foreign policy has been more noteworthy for the quantity than the quality of its intellectual products. Three recent developing trends in this field give some hope that tomorrow will be better. They should provide analyti­cal tools and improved empirical re­search that will be helpful to the practi­tioner as well as the student of foreign policy

Mature adults becoming teachers : sailing toward Ithaka.

My research was an eighteen-month study of how mature, college-educated adults (age range 24-56, professional experience diverse) transformed themselves from the men and women who entered a small, independent, field-based teacher preparation program in August into effective, state-certified teachers by the following June. The study continued into the next school year, tracing further development of each of the originally selected nine intern teachers, seven in their own classrooms, two, finally, in other chosen roles. The research was an interpretive study, combining the use of questionnaires, classroom observation, selections from journals, and in-depth interview/discussions with each of the nine participants at four times during the eighteen months. The interns\u27 own assessments of the time in different classroom settings with children/young adults and experienced mentor teachers, were that the extensive daily experiences were pivotal in moving them toward a perception of self as teacher. This perception represents an aspect of human development described by Piaget as decalage, by Kegan as the whole becoming a part of a new whole, by Perry as commitment in relativism. Learning of this depth and human development are synonymous. Analysis of reflective comments of participants revealed how each mature intern teacher wove knowledge, attitudes, materials, educational theory, support from his/her mentor teacher, and personality into the unique teacher she/he was becoming. The intensity of the intern experience led the majority of the interns, by the middle of the second semester, to know the kind of teacher each would be, to be articulate in discussing her/his approach to teaching in both theoretical and practical terminology, and to display effective leadership in the classroom. The route to this knowing I call an epistemology of learning. This is a study of individuals who know what they have learned in such a deep, meaningful sense that they are confident in their useable knowledge. The route to this knowing is interactive and collaborative, experiential and theoretical; the resultant learning is deeply meaningful in that it incorporates intellect and emotion as the whole person develops dynamically (Kegan), works through the imbalance of transition to a more inclusive view of the world (Perry), and senses the ego-integrity of a generative self (Erikson)

Lumped dynamic analysis and design of a high-performance reciprocating-piston expander

A spatially - lumped dynamic model of a reciprocating - piston expander is presented in this paper. The model accounts for the three main loss mechanisms in realistic piston machines, namely: pressure losses through the intake and exhaust valves, heat transfer between the gas and the surrounding cylinder walls, and the mass leakage between the compression/expansion chamber and the crankcase throu gh the piston rings. The model also accounts for real - gas effects with the fluid properties calculated from t he NIST database using REFPROP. The numerical calculations are first compared with experimental pressure - volume - temperature data obtained on a cust om reciprocating - piston gas spring over a r ange of oscillation frequencies. The comparison between numerical and experimental results shows good agreement. It also allows the most accurate heat transfer correlation to be selected for calculating the gas - to - wall in - cylinder heat transfer. The semi - heuristic modelling tool is then used to design an expander for specific pressure ratio s and mass flowrate, and to predict the thermodynamic performance of the piston device over a range of part - load conditions

Dynamic control strategies for a solar-ORC system using first-law dynamic and data-driven machine learning models

In this study, we developed and assessed the potential of dynamic control strategies for a domestic scale 1-kW solar thermal power system based on a non-recuperated organic Rankine cycle (ORC) engine coupled to a solar energy system. Such solar-driven systems suffer from part-load performance deterioration due to diurnal and inter-seasonal fluctuations in solar irradiance and ambient temperature. Real-time control strategies for adjusting the operating parameters of these systems have shown great potential to optimise their transient response to time-varying conditions, thus allowing significant gains in the power output delivered by the system. Dynamic model predictive control strategies rely on the development of computationally efficient, fast-solving models. In contrast, traditional physics-based dynamic process models are often too complex to be used for real-time controls. Machine learning techniques (MLTs), especially deep learning artificial neural networks (ANN), have been applied successfully for controlling and optimising nonlinear dynamic systems. In this study, the solar system was controlled using a fuzzy logic controller with optimised decision parameters for maximum solar energy absorption. For the sake of obtaining the optimal ORC thermal efficiency at any instantaneous time, particularly during part-load operation, the first-law ORC model was first replaced by a fast-solving feedforward network model, which was then integrated with a multi-objective genetic algorithm, such that the optimal ORC operating parameters can be obtained. Despite the fact that the feedforward network model was trained using steady-state ORC performance data, it showed comparable results compared with the first-principle model in the dynamic context, with a mean absolute error of 3.3 percent for power prediction and 0.186 percentage points for efficiency prediction

Electricity demand reduction through waste heat recovery in olefins plants based on a technology-agnostic approach

Developing systematic approaches for the identification of optimal WHR options in industrial applications is key to reducing plant-scale energy demands. In particular, electricity consumption accounts for more than half of industrial energy use, and its share is expected to grow with progressive electrification. In this paper, industrial WHR technologies including organic Rankine cycle (ORC) and absorption systems are investigated, and tools are developed to understand the sustainability and techno-economic impact of integrating these technologies within industrial processes and facilities. We specifically propose a data-driven technology-agnostic approach to evaluate the use of heat engines, which can in practice be ORC systems, and thermally-driven (i.e., absorption) heat pumps in the context of industrial WHR for plant-scale electricity demand reduction. The aim of this work is to explore three pathways for achieving efficiency improvements in bulk chemicals plants, represented here by olefins production facilities: (i) direct onsite power generation; (ii) enhancement of existing power generation processes; and (iii) reduction in power consumption by compressor efficiency improvements through waste-heat-driven cooling. The techno-economic performance of these technologies is assessed for five different countries representing a diverse portfolio of climates, technical and economic parameters (including utility prices), using fine-tuned thermodynamic and market-based costing models. The results reveal that the proposed approach has the potential to reduce emissions by between 5,000 tCO2(eq.)/year and 101,500 tCO2(eq.)/year depending on the scenario. The marginal abatement cost of the proposed solutions ranges from −1,200 $/tCO2(eq.) to −35$/tCO2(eq.), with a payback time between 1.5 and 8 years depending on the scenario considered

Electricity demand reduction through waste heat recovery in olefins plants based on a technology-agnostic approach

Developing systematic approaches for the identification of optimal WHR options in industrial applications is key to reducing plant-scale energy demands. In particular, electricity consumption accounts for more than half of industrial energy use, and its share is expected to grow with progressive electrification. In this paper, industrial WHR technologies including organic Rankine cycle (ORC) and absorption systems are investigated, and tools are developed to understand the sustainability and techno-economic impact of integrating these technologies within industrial processes and facilities. We specifically propose a data-driven technology-agnostic approach to evaluate the use of heat engines, which can in practice be ORC systems, and thermally-driven (i.e., absorption) heat pumps in the context of industrial WHR for plant-scale electricity demand reduction. The aim of this work is to explore three pathways for achieving efficiency improvements in bulk chemicals plants, represented here by olefins production facilities: (i) direct onsite power generation; (ii) enhancement of existing power generation processes; and (iii) reduction in power consumption by compressor efficiency improvements through waste-heat-driven cooling. The techno-economic performance of these technologies is assessed for five different countries representing a diverse portfolio of climates, technical and economic parameters (including utility prices), using fine-tuned thermodynamic and market-based costing models. The results reveal that the proposed approach has the potential to reduce emissions by between 5,000 tCO2(eq.)/year and 101,500 tCO2(eq.)/year depending on the scenario. The marginal abatement cost of the proposed solutions ranges from −1,200 $/tCO2(eq.) to −35$/tCO2(eq.), with a payback time between 1.5 and 8 years depending on the scenario considered

Regulation of Lifespan in Drosophila by Modulation of Genes in the TOR Signaling Pathway

In many species, reducing nutrient intake without causing malnutrition extends lifespan 1, 2, 3. Like DR (dietary restriction), modulation of genes in the insulin-signaling pathway, known to alter nutrient sensing, has been shown to extend lifespan in various species 1, 2, 3, 4. In Drosophila, the target of rapamycin (TOR) and the insulin pathways have emerged as major regulators of growth and size. Hence we examined the role of TOR pathway genes in regulating lifespan by using Drosophila. We show that inhibition of TOR signaling pathway by alteration of the expression of genes in this nutrient-sensing pathway, which is conserved from yeast to human, extends lifespan in a manner that may overlap with known effects of dietary restriction on longevity. In Drosophila, TSC1 and TSC2 (tuberous sclerosis complex genes 1 and 2) act together to inhibit TOR (target of rapamycin), which mediates a signaling pathway that couples amino acid availability to S6 kinase, translation initiation, and growth [5]. We find that overexpression of dTsc1, dTsc2, or dominant-negative forms of dTOR or dS6K all cause lifespan extension. Modulation of expression in the fat is sufficient for the lifespan-extension effects. The lifespan extensions are dependent on nutritional condition, suggesting a possible link between the TOR pathway and dietary restriction

Bioaccumulation of perfluoroalkyl compounds in midge (Chironomus riparius) larvae exposed to sediment

Midge larvae (Chironomus riparius) were exposed to sediments from a deposition sampled at a site along the Rhône River (France) downstream of an industrial site releasing various perfluorinated chemicals. This sediment is characterized by high concentrations of perfluoroundecanoic acid (PFUnA) and perfluorotridecanoic acid (PFTrDA) and a low perfluorooctane sulfonate (PFOS) concentration. Concentrations of 23 perfluoroalkyl compounds, including C4eC14 carboxylate acids, C4eC10 sulfonates, and seven precursors, were analyzed in overlying and pore water, sediment, and larvae. Midge larvae accumulated carboxylate acids (C11eC14), PFOS, and two precursors (perfluorooctane sulfonamide: FOSA and 6:2 fluorotelomer sulfonic acid, 6:2 FTSA). These substances accumulated mainly during the fourth instar larvae exponential growth phase. Accumulation of 6:2 FTSA, PFUnA, and PFOS occured via trophic and tegumentary routes. Other compounds mainly accumulated from food. Kinetics followed a partition model, from which uptake and elimination constants were derived

Once-Weekly Exenatide Versus Once- or Twice-Daily Insulin Detemir: Randomized, open-label, clinical trial of efficacy and safety in patients with type 2 diabetes treated with metformin alone or in combination with sulfonylureas

OBJECTIVEdThis multicenter, open-label, parallel-arm study compared the efficacy and safety of exenatide once weekly (EQW) with titrated insulin detemir in patients with type 2 diabetes inadequately controlled with metformin (with or without sulfonylureas). RESEARCH DESIGN AND METHODSdPatients were randomized to EQW (2 mg) or detemir (once or twice daily, titrated to achieve fasting plasma glucose #5.5 mmol/L) for 26 weeks. The primary outcome was proportion of patients achieving A1C #7.0% and weight loss $1.0 kg at end point, analyzed by means of logistic regression. Secondary outcomes included measures of glycemic control, cardiovascular risk factors, and safety and tolerability. RESULTSdOf 216 patients (intent-to-treat population), 111 received EQW and 105 received detemir. Overall, 44.1% (95% CI, 34.7–53.9) of EQW-treated patients compared with 11.4% (6.0–19.1) of detemir-treated patients achieved the primary outcome (P , 0.0001). Treatment with EQW resulted in significantly greater reductions than detemir in A1C (least-square mean 6 SE, 21.30 6 0.08% vs. 20.88 6 0.08%; P , 0.0001) and weight (22.7 6 0.3 kg vs. +0.8 6 0.4 kg; P , 0.0001). Gastrointestinal-related and injection site–related adverse events occurred more frequently with EQW than with detemir. There was no major hypoglycemia in either group. Five (6%) patients in the EQW group and six (7%) patients in the detemir group experienced minor hypoglycemia; only one event occurred without concomitant sulfonylureas (detemir group). CONCLUSIONSdTreatment with EQW resulted in a significantly greater proportion of patients achieving target A1C and weight loss than treatment with detemir, with a low risk of hypoglycemia. These results suggest that EQW is a viable alternative to insulin detemir treatment in patients with type 2 diabetes with inadequate glycemic control using oral antidiabetes drugs

Techno-economic comparison of hydrogen- and electricity-driven technologies for the decarbonisation of domestic heating

Sustainable transition pathways currently being proposed for moving away from the use of natural gas and oil in domestic heating focus on two main energy vectors: electricity and hydrogen. The former transition would most likely be implemented using electric vapour-compression heat pumps, which are currently experiencing market growth in many industrialised countries. Electric heat pumps have proven to be an efficient alternative to gas boilers under certain conditions, but their techno-economic potential is highly dependent on the local climate conditions. Hydrogen-based heating systems, which could potentially utilise existing natural gas infrastructure, are being proposed as providing an attractive opportunity to maximise the use of existing assets to facilitate the energy-system transition. In this case, hydrogen can substitute natural gas in boilers or in thermally driven absorption heat pumps. Both heating system transition pathways may involve either installing new technologies at the household level or producing heat in centralised hubs and distributing it via district-heating systems. Although the potential of hydrogen in the context of heating decarbonisation has been explored in the past, a comprehensive comparison of electricity- and hydrogen-driven domestic heating options is lacking in literature. In this paper, a thermodynamic and economic methodology is developed to assess the competitiveness of a domestic-scale ammonia-water absorption heat pump driven by heat from a hydrogen boiler compared to a standalone hydrogen boiler, a classic vapour-compression heat pump and district heating, all from a homeowner’s perspective. Using a previously developed electric heat pump model, the different systems are compared for various climate conditions and fuel-price scenarios under a unified framework. The coefficient of performance of the absorption heat pump system under design conditions and the total system cost are found to be 1.4 and £5400, respectively. Comparing the annualised total costs of the options under consideration, it is shown that, assuming the future price of hydrogen for domestic end-users can be below 0.12 £/kWh, absorption heat pumps and hydrogen boilers can become competitive domestic heating technologies, and otherwise, electrification and the use of vapour-compression heat pump will be preferred