1,118 research outputs found
The Influence of Gas-to-Liquids and Natural Gas Production Technology Penetration on the Crude Oil-Natural Gas Price Relationship
The paper examines conditions under which gas-to-liquids (GTL) technology penetration shifts the crude oil-natural gas price ratio. Technologies that enable direct substitution across fuels, as GTL does, may constrain the price ratio within certain bounds. We analyze the forecasted evolution of the crude oil-natural gas price ratio over the next several decades under alternative assumptions about the availability and cost of GTL and its natural gas feedstock. We do this using a computable general equilibrium model of the global economy with a focus on the refinery sector in the U.S. Absent GTL, a base case forecast of global economic growth over the next few decades produces dramatic increases in the oil-natural gas price ratio. This is because there is a more limited supply of low-cost crude oil resources than natural gas resources. The availability of GTL at conventional forecasts of cost and efficiency does not materially change the picture because it is too expensive to enhance direct competition between the two as fuels in the transportation sector. GTL only modulates the increasing oil-gas price ratio if both (i) natural gas is much cheaper to produce, and (ii) GTL is less costly and more efficient than conventional forecasts.This work has been funded in part by BP, the MITEI ENI Energy Fellowship, the MITEI Martin Family Fellowship, and sponsors of MIT’s Joint Program on the Science and Policy of Global Change. The Joint Program on the Science and Policy of Global Change is funded by the U.S. Department of Energy, Office of Science under grants DE-FG02-94ER61937, DE-FG02- 08ER64597, DE-FG02-93ER61677, DE-SC0003906, DE-SC0007114, XEU-0-9920-01; the U.S. Department of Energy, Oak Ridge National Laboratory under Subcontract 4000109855; the U.S. Environmental Protection Agency under grants XA-83240101, PI-83412601-0, RD-83427901-0, XA-83505101-0, XA-83600001-1, and subcontract UTA12-000624; the U.S. National Science Foundation under grants AGS-0944121, EFRI-0835414, IIS-1028163, ECCS-1128147, ARC-1203526, EF-1137306, AGS-1216707, and SES-0825915; the U.S. National Aeronautics and Space Administration (NASA) under grants NNX06AC30A, NNX07AI49G, NNX11AN72G and Sub Agreement No. 08-SFWS-209365.MIT; the U.S. Federal Aviation Administration under grants 06-C-NE-MIT, 09-C-NE-MIT, Agmt. No. 4103-30368; the U.S. Department of Transportation under grant DTRT57-10-C-10015; the Electric Power Research Institute under grant EP-P32616/C15124, EP-P8154/C4106; the U.S. Department of Agriculture under grant 58-6000-2-0099, 58-0111-9-001; and a consortium of 35 industrial and foundation sponsors (for the complete list see: http://globalchange.mit.edu/sponsors/all)
Struggling for food in a time of crisis: Responsibility and paradox
Responsibility is a useful lens through which to examine the current state of food poverty in the UK in the context of the Covid‐19 crisis, noting that this concept contains several paradoxes. Currently, responsibility involves the voluntary sector, the food industry and the state, a situation which the author has been exploring for the last five years in an ethnographic study of food poverty and food aid in the UK. Food aid organizations, especially food banks, have mushroomed during the period of austerity. This reveals the first paradox: namely, that the existence of food banks conveys the message that ‘something is being done’, but in actuality this is very far from being sufficient to meet the needs of either the ‘old’ or ‘new’ food insecure. The second paradox is that at the onset of the crisis, a government which had been responsible for inflicting austerity on the country for 10 years, dramatically reversed some of its policies. However, predictably, this did not change the situation vis‐à‐vis food insecurity. The third paradox is that the frequent rhetoric invoking the two world wars has not resulted in lessons being learned – notably, the creation of a ministry to deal with food and rationing, as in the Second World War. The final paradox relates to Brexit and its likely deleterious effects on food security, particularly if no ‘deal’ is achieved with the European Union, as seems likely. The voluntary food aid sector, try as it may, cannot possibly assume responsibility for the long‐standing and now hugely increased problems of food insecurity. That belongs to the state
Citizen Science 2.0 : Data Management Principles to Harness the Power of the Crowd
Citizen science refers to voluntary participation by the general public in scientific endeavors. Although citizen science has a long tradition, the rise of online communities and user-generated web content has the potential to greatly expand its scope and contributions. Citizens spread across a large area will collect more information than an individual researcher can. Because citizen scientists tend to make observations about areas they know well, data are likely to be very detailed. Although the potential for engaging citizen scientists is extensive, there are challenges as well. In this paper we consider one such challenge – creating an environment in which non-experts in a scientific domain can provide appropriate and accurate data regarding their observations. We describe the problem in the context of a research project that includes the development of a website to collect citizen-generated data on the distribution of plants and animals in a geographic region. We propose an approach that can improve the quantity and quality of data collected in such projects by organizing data using instance-based data structures. Potential implications of this approach are discussed and plans for future research to validate the design are described
Prediction of extreme events in the OFC model on a small world network
We investigate the predictability of extreme events in a dissipative
Olami-Feder-Christensen model on a small world topology. Due to the mechanism
of self-organized criticality, it is impossible to predict the magnitude of the
next event knowing previous ones, if the system has an infinite size. However,
by exploiting the finite size effects, we show that probabilistic predictions
of the occurrence of extreme events in the next time step are possible in a
finite system. In particular, the finiteness of the system unavoidably leads to
repulsive temporal correlations of extreme events. The predictability of those
is higher for larger magnitudes and for larger complex network sizes. Finally,
we show that our prediction analysis is also robust by remarkably reducing the
accessible number of events used to construct the optimal predictor.Comment: 5 pages, 4 figure
Routine measurement of serum procalcitonin allows antibiotics to be safely withheld in patients admitted to hospital with SARS-CoV-2 infection
Background. It can be a diagnostic challenge to identify COVID-19 patients without bacterial co-infection in whom antibiotics can be safely stopped. We sought to evaluate the validity of a guideline that recommends withholding antibiotics in patients with a low serum procalcitonin (PCT).
Methods. We retrospectively collected 28-day outcome data on patients admitted to Sheffield Teaching Hospitals NHS Foundation Trust, UK, between 5 March and 15 April 2020, with a positive SARS-CoV-2 polymerase chain reaction (PCR) and PCT within 48 hours of diagnosis. PCT was considered negative if ≤0.25ng/ml and positive if >0.25ng/ml. Primary outcomes included antibiotic consumption, mortality, intensive care admission and length of hospital stay.
Results. 368 patients met the inclusion criteria; 218 (59%) had a negative PCT and 150 (41%) positive. At 48 hours post-diagnosis, 73 (33%) of those with a negative PCT were receiving antimicrobials compared to 126 (84%) with a positive PCT (p<0.001), with a corresponding reduction in antimicrobial usage over 28 days (median DDD of 3.0 vs 6.8 (p<0.001); median DOT 2 vs 5 days (p<0.001) between the negative and positive PCT groups.) In the negative PCT group, there were fewer deaths (62 (28%) vs. 54 (36%), (p=0.021)) and critical care admissions (19 (9%) vs. 28 (19%), (p=0.007)) than in the positive PCT group. Median length of hospital stay was 8.7 and 9 days in the negative and positive PCT groups respectively.
Conclusions. Procalcitonin is a valuable tool in the assessment of patients with SARS-CoV-2 infection, safely reducing the potential burden of unnecessary antibiotic usage
Inflation and the Scale Dependent Spectral Index: Prospects and Strategies
We consider the running of the spectral index as a probe of both inflation
itself, and of the overall evolution of the very early universe. Surveying a
collection of simple single field inflationary models, we confirm that the
magnitude of the running is relatively consistent, unlike the tensor amplitude,
which varies by orders of magnitude. Given this target, we confirm that the
running is potentially detectable by future large scale structure or 21 cm
observations, but that only the most futuristic measurements can distinguish
between these models on the basis of their running. For any specified
inflationary scenario, the combination of the running index and unknown
post-inflationary expansion history induces a theoretical uncertainty in the
predicted value of the spectral index. This effect can easily dominate the
statistical uncertainty with which Planck and its successors are expected to
measure the spectral index. More positively, upcoming cosmological experiments
thus provide an intriguing probe of physics between TeV and GUT scales by
constraining the reheating history associated with any specified inflationary
model, opening a window into the "primordial dark age" that follows the end of
inflation.Comment: 32 pages. v2 and v3 Minor reference updates /clarification
Young people, crime and school exclusion: a case of some surprises
During the 1990s the number of young people being permanently excluded from schools in England and Wales increased dramatically from 2,910 (1990/91) to a peak of 12,700 (1996/97). Coinciding with this rise was a resurgence of the debate centring on lawless and delinquent youth. With the publication of Young People and Crime (Graham and Bowling 1995) and Misspent Youth (Audit Commission 1996) the 'common sense assumption' that exclusion from school inexorably promoted crime received wide support, with the school excludee portrayed as another latter day 'folk devil'. This article explores the link between school exclusion and juvenile crime, and offers some key findings from a research study undertaken with 56 young people who had experience of being excluded from school. Self-report interview questions reveal that whilst 40 of the young people had offended, 90% (36) reported that the onset of their offending commenced prior to their first exclusion. Moreover, 50 (89.2% of the total number of young people in the sample), stated that they were no more likely to offend subsequent to being excluded and 31 (55.4%) stated that they were less likely to offend during their exclusion period. Often, this was because on being excluded, they were 'grounded' by their parents
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