Alternative vehicles powered by electricity or hydrogen hold the potential to solve a number of challenges that relate to automobile use, such as climate change, deterioration of local air quality, ...security of energy supply, and high fuel prices. This article addresses the question as to how a transition to vehicles powered by hydrogen or electricity could take place. Recognizing that transitions result from joint development of technology and society, a co-evolutionary, multi-level perspective is adopted. The perspective is used to analyze the dynamics of the relationship between car manufacturers and consumers and developments that put pressure on this relationship. Building on the analysis, two sets of scenarios for a transition to battery-electric and fuel cell vehicles are identified. In one set of scenarios, tightening emissions regulation stimulates carmakers to scale up experiments with alternative vehicles, moving them into the commercialization phase. In the other set, rising fuel prices prompt carmakers to first extend their current product line-up with plug-in versions, and later with battery-electric and fuel cell vehicles. The two scenarios have different implications for the actors involved and for the requisite supporting infrastructure.
Overview of the SPARC tokamak Creely, A. J.; Greenwald, M. J.; Ballinger, S. B. ...
Journal of plasma physics,
10/2020, Letnik:
86, Številka:
5
Journal Article
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The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ($B_0 = 12.2$ T), compact ($R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak ...with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in a compact device. The goal of $Q>2$ is achievable with conservative physics assumptions ($H_{98,y2} = 0.7$) and, with the nominal assumption of $H_{98,y2} = 1$, SPARC is projected to attain $Q \approx 11$ and $P_{\textrm {fusion}} \approx 140$ MW. SPARC will therefore constitute a unique platform for burning plasma physics research with high density ($\langle n_{e} \rangle \approx 3 \times 10^{20}\ \textrm {m}^{-3}$), high temperature ($\langle T_e \rangle \approx 7$ keV) and high power density ($P_{\textrm {fusion}}/V_{\textrm {plasma}} \approx 7\ \textrm {MW}\,\textrm {m}^{-3}$) relevant to fusion power plants. SPARC's place in the path to commercial fusion energy, its parameters and the current status of SPARC design work are presented. This work also describes the basis for global performance projections and summarizes some of the physics analysis that is presented in greater detail in the companion articles of this collection.
Experiments in the DIII-D tokamak show that fast-ion transport suddenly becomes stiff above a critical threshold in the presence of many overlapping small-amplitude Alfvén eigenmodes (AEs). The ...threshold is phase-space dependent and occurs when particle orbits become stochastic due to resonances with AEs. Above threshold, equilibrium fast-ion density profiles are unchanged despite increased drive, and intermittent fast-ion losses are observed. Fast-ion Dα spectroscopy indicates radially localized transport of the copassing population at radii that correspond to the location of midcore AEs. The observation of stiff fast-ion transport suggests that reduced models can be used to effectively predict alpha profiles, beam ion profiles, and losses to aid in the design of optimized scenarios for future burning plasma devices.
Extrinsic information transfer (EXIT) charts are a tool for predicting the convergence behavior of iterative processors for a variety of communication problems. A model is introduced that applies to ...decoding problems, including the iterative decoding of parallel concatenated (turbo) codes, serially concatenated codes, low-density parity-check (LDPC) codes, and repeat-accumulate (RA) codes. EXIT functions are defined using the model, and several properties of such functions are proved for erasure channels. One property expresses the area under an EXIT function in terms of a conditional entropy. A useful consequence of this result is that the design of capacity-approaching codes reduces to a curve-fitting problem for all the aforementioned codes. A second property relates the EXIT function of a code to its Helleseth-Klove-Levenshtein information functions, and thereby to the support weights of its subcodes. The relation is via a refinement of information functions called split information functions, and via a refinement of support weights called split support weights. Split information functions are used to prove a third property that relates the EXIT function of a linear code to the EXIT function of its dual.
Abstract Imaging biomarkers have a potential to depict the hallmarks of cancers that characterise cancer cells as compared to normal cells. One pertinent example is 3′-deoxy-3′-18 F-fluorothymidine ...positron emission tomography (18 FFLT-PET), which allows non-invasive in vivo assessment of tumour proliferation. Most importantly, 18 FFLT does not seem to be accumulating in inflammatory processes, as seen in 18 F-fludeoxyglucose, the most commonly used PET tracer for assessment of cell metabolism. 18 FFLT could therefore provide additional information about the tumour biology before, during and after treatment. This systematic review focuses on the use of 18 FFLT-PET tumour uptake values as a measure of tumour response to therapeutic interventions. The clinical studies which evaluated the role of 18 FFLT-PET as a measure of tumour response to treatment are summarised and the evidence linking 18 FFLT-PET tumour uptake values with clinical outcome is evaluated.
A new, rapid Fourier transform near infrared (FT-NIR) spectroscopic procedure is described to screen for the authenticity of extra virgin olive oils (EVOO) and to determine the kind and amount of an ...adulterant in EVOO. To screen EVOO, a partial least squares (PLS1) calibration model was developed to estimate a newly created FT-NIR index based mainly on the relative intensities of two unique carbonyl overtone absorptions in the FT-NIR spectra of EVOO and other mixtures attributed to volatile (5280 cm⁻¹) and non-volatile (5180 cm⁻¹) components. Spectra were also used to predict the fatty acid (FA) composition of EVOO or samples spiked with an adulterant using previously developed PLS1 calibration models. Some adulterated mixtures could be identified provided the FA profile was sufficiently different from those of EVOO. To identify the type and determine the quantity of an adulterant, gravimetric mixtures were prepared by spiking EVOO with different concentrations of each adulterant. Based on FT-NIR spectra, four PLS1 calibration models were developed for four specific groups of adulterants, each with a characteristic FA composition. Using these different PLS1 calibration models for prediction, plots of predicted vs. gravimetric concentrations of an adulterant in EVOO yielded linear regression functions with four unique sets of slopes, one for each group of adulterants. Four corresponding slope rules were defined that allowed for the determination of the nature and concentration of an adulterant in EVOO products by applying these four calibration models. The standard addition technique was used for confirmation.
Background Induction chemotherapy before surgical resection increases survival compared with surgical resection alone in patients with stage IIIA-N2 non–small-cell lung cancer (NSCLC). We ...hypothesized that, following a response to induction chemotherapy, surgical resection would be superior to thoracic radiotherapy as locoregional therapy. Methods Selected patients with histologic or cytologic proven stage IIIA-N2 NSCLC were given three cycles of platinum-based induction chemotherapy. Responding patients were subsequently randomly assigned to surgical resection or radiotherapy. Survival curves were estimated using Kaplan–Meier analyses from time of randomization. Results Induction chemotherapy resulted in a response rate of 61% (95% confidence interval CI = 57% to 65%) among the 579 eligible patients. A total of 167 patients were allocated to resection and 165 to radiotherapy. Of the 154 (92%) patients who underwent surgery, 14% had an exploratory thoracotomy, 50% a radical resection, 42% a pathologic downstaging, and 5% a pathologic complete response; 4% died after surgery. Postoperative radiotherapy was administered to 62 (40%) of patients in the surgery arm. Among the 154 (93%) irradiated patients, overall compliance to the radiotherapy prescription was 55%, and grade 3/4 acute and late esophageal and pulmonary toxic effects occurred in 4% and 7%; one patient died of radiation pneumonitis. Median and 5-year overall survival for patients randomly assigned to resection versus radiotherapy were 16.4 versus 17.5 months and 15.7% versus 14%, respectively (hazard ratio = 1.06, 95% CI = 0.84 to 1.35). Rates of progression-free survival were also similar in both groups. Conclusion In selected patients with pathologically proven stage IIIA-N2 NSCLC and a response to induction chemotherapy, surgical resection did not improve overall or progression-free survival compared with radiotherapy. In view of its low morbidity and mortality, radiotherapy should be considered the preferred locoregional treatment for these patients.
Models of ecosystem carbon (C) balance generally assume a strong relationship between NPP, litter inputs, and soil C accumulation, but there is little direct evidence for such a coupled relationship. ...Using a unique 50-year detrital manipulation experiment in a mixed deciduous forest and in restored prairie grasslands in Wisconsin, combined with sequential density fractionation, isotopic analysis, and short-term incubation, we examined the effects of detrital inputs and removals on soil C stabilization, destabilization, and quality. Both forested sites showed greater decline in bulk soil C content in litter removal plots (55 and 66 %) compared to increases in litter addition plots (27 and 38 % increase in surface soils compared to controls). No accumulation in the mineral fraction C was observed after 50 years of litter addition of the two forested plots, thus increases in the light density fraction pool drove patterns in total C content. Litter removal across both ecosystem types resulted in a decline in both free light fraction and mineral C content, with an overall 51 % decline in mineral-associated carbon in the intermediate (1.85–2.4 g cm⁻³) density pool; isotopic data suggest that it was preferentially younger C that was lost. In contrast to results from other, but younger litter manipulation sites, there was with no evidence of priming even in soils collected after 28 years of treatment. In prairie soils, aboveground litter exclusion had an effect on C levels similar to that of root exclusion, thus we did not see evidence that root-derived C is more critical to soil C sequestration. There was no clear evidence that soil C quality changed in litter addition plots in the forested sites; δ¹³C and Δ¹⁴C values, and incubation estimates of labile C were similar between control and litter addition soils. C quality appeared to change in litter removal plots; soils with litter excluded had Δ¹⁴C values indicative of longer mean residence times, δ¹³C values indicative of loss of fresh plant-derived C, and decreases in all light fraction C pools, although incubation estimates of labile C did not change. In prairie soils, δ¹³C values suggest a loss of recent C4-derived soil C in litter removal plots along with significant increases in mean residence time, especially in plots with removal of roots. Our results suggest surface mineral soils may be vulnerable to significant C loss in association with disturbance, land use change, or perhaps even climate change over century–decadal timescales, and also highlight the need for longer-term experimental manipulations to study soil organic matter dynamics.
Abstract
The effect of the plasma shaping (triangularity and elongation) on the continuous spectrum, frequency gaps, and number of eigenmodes is studied. The plasma shaping affects the coupling ...between Alfvén and slow magnetosonic waves via the geodesic magnetic curvature and the plasma pressure. The Alfvén-slow coupling creates a large number of new gaps in the continuous spectrum below the Alfvén frequency where discrete modes can reside. In ideal magnetohydrodynamic simulations a large number (a few hundred or more) of potential eigenmodes are found. The number of eigenmodes is correlated with the maximum geodesic curvature and a minimum number of possible discrete eigenmodes is found at a negative triangularity of −0.3. It is hypothesized that these possible eigenmodes form a low amplitude and dense discrete spectrum, which can be studied experimentally.
Milk fat is a complex mixture of geometric and positional isomers of monounsaturated and polyunsaturated, including short-, long- and branch-chain fatty acids (FAs). There has been partial success to ...resolve this mixture of FAs using different GC temperature programs, or a combination of GC isothermal and temperature programs. To overcome the problem associated with overlapping isomers prior silver-ion separation was recommended. However, this procedure is time consuming and not practical for routine analysis. In addition, previous methods focused mainly on the trans and cis isomers of 18:1. The present method takes advantage of differences in the relative elution times between different types of FAs. The method involved analyzing each milk fat using the same highly polar 100-m capillary column and GC instrument, and conducting two separations using temperature programs that plateau at 175 and 150 °C. The relative shift among the geometric and positional isomers at these two temperature settings was enough to permit identification of most of the trans and cis 16:1, 18:1 and 20:1, the c/t-18:2 and the c/c/t-18:3 isomers found in milk fat. The identity of these FAs was confirmed by prior separation of the total fatty acid methyl esters (FAMEs) of milk fat using Ag⁺-SPE columns, and comparing the fractions to the total milk fat. The Ag⁺-SPE technique was modified to obtain pure saturated, trans- and cis-monounsaturated and diunsaturated FAMEs. By combining the results from these two separate GC analyses, knowing the elution order, it was possible to determine most of the geometric and positional isomers of 16:1, 18:1, 20:1, 18:2 and 18:3 without a prior silver-ion separation. Only few minor FAs could not be resolved, notable the conjugated linoleic acid isomers that still required the complimentary Ag⁺-HPLC separation. The two GC temperature programs have been successfully used to routinely analyze most FA isomers in total milk and beef fats in about 200 min without the use of prior silver-ion separations.
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