Sequential Implementation of Monte Carlo Tests with Uniformly Bounded Resampling Risk

This paper introduces an open-ended sequential algorithm for computing the p-value of a test using Monte Carlo simulation. It guarantees that the resampling risk, the probability of a different decision than the one based on the theoretical p-value, is uniformly bounded by an arbitrarily small constant. Previously suggested sequential or non-sequential algorithms, using a bounded sample size, do not have this property. Although the algorithm is open-ended, the expected number of steps is finite, except when the p-value is on the threshold between rejecting and not rejecting. The algorithm is suitable as standard for implementing tests that require (re-)sampling. It can also be used in other situations: to check whether a test is conservative, iteratively to implement double bootstrap tests, and to determine the sample size required for a certain power.Comment: Major Revision 15 pages, 4 figure

The Effect of CO2 Pricing on Conventional and Non-Conventional Oil Supply and Demand

What would be the effect of CO2 pricing on global oil supply and demand? This paper introduces a model describing the interaction between conventional and non-conventional oil supply in a Hotelling framework and under CO2 constraints. The model assumes that nonconventional crude oil enters the market when conventional oil supply alone is unable to meet demand, and the social cost of CO2 is included in the calculation of the oil rent at that time. The results reveal the effect of a CO2 tax set at the social cost of CO2 on oil price and demand and the uncertainty associated with the time when conventional oil production might become unable to meet demand. The results show that a tax on CO2 emissions associated with fuel use would reduce oil demand despite the effect of lower future rents, and would delay the time when conventional oil supply is unable to satisfy demand. More precisely, between 81 and 99% of the CO2 tax is carried into the oil price despite the counter-balancing effect of the reduced rent. A CO2 tax on fuel use set at the social cost of CO2 would delay by 25 years the time when conventional oil production is unable to meet oil demand, from 2019 to 2044 (mean value). The results show that this date is very sensitive to the price elasticity of demand and the demand growth rate, which shows the great potential of demand-side measures to smooth the transition towards low-carbon liquid fuel alternatives

Supplying Synthetic Crude Oil from Canadian Oil Sands: A Comparative Study of the Costs and CO2 Emissions of Mining and In-Situ Recovery

High crude oil prices and the eventual decline of conventional oil production raise the issue of alternative fuels such as non-conventional oil. The paper describes a simple probabilistic model of the costs of synthetic crude oil (SCO) produced from Canadian oil sands. Synthetic crude oil is obtained by upgrading bitumen that is first produced through mining or in-situ recovery techniques. This forward-looking analysis quantifies the effects of learning and production constraints on the costs of supplying synthetic crude oil from Canadian bitumen deposits. The results show the uncertainties associated with the future costs of synthetic crude oil. Carbon costs have a large impact of the total costs of synthetic crude oil, in particular in the case of synthetic crude oil from in-situ bitumen, due to the carbon-intensity of the recovery techniques. The influence of each parameter on the supply costs is examined. In the case of mined SCO, the maximum production rate, the ultimate recovery rate and the depletion parameters show the largest influence on the results, while learning parameters dominate in the case of in-situ SCO

Do early-life exposures explain why more advantaged children get eczema? Findings from the U.K. Millennium Cohort Study

Background: Atopic dermatitis (eczema) in childhood is socially patterned, with higher incidence in more advantaged populations. However, it is unclear what factors explain the social differences. Objectives: To identify early-life risk factors for eczema, and to explore how early-life risk factors explain any differences in eczema. Methods: We estimated odds ratios (ORs) for ever having had eczema by age 5 years in 14 499 children from the U.K. Millennium Cohort Study (MCS), with a focus on maternal, antenatal and early-life risk factors and socioeconomic circumstances (SECs). Risk factors were explored to assess whether they attenuated associations between SECs and eczema. Results: Overall 35·1% of children had ever had eczema by age 5 years. Children of mothers with degree-level qualifications vs. no educational qualifications were more likely to have eczema (OR 1·52, 95% confidence interval 1·31–1·76), and there was a gradient across the socioeconomic spectrum. Maternal atopy, breastfeeding (1–6 weeks and ≥ 6 months), introduction of solids under 4 months or cow's milk under 9 months, antibiotic exposure in the first year of life and grime exposure were associated with an increased odds of having eczema. Female sex, Pakistani and Bangladeshi ethnicity, smoking during pregnancy, exposure to environmental tobacco smoke and having more siblings were associated with reduced odds for eczema. Controlling for maternal, antenatal and early-life characteristics (particularly maternal smoking during pregnancy, breastfeeding and number of siblings) reduced the OR for eczema to 1·26 (95% confidence interval 1·03–1·50) in the group with the highest educational qualifications compared with the least. Conclusions: In a representative U.K. child cohort, eczema was more common in more advantaged children. This was explained partially by early-life factors including not smoking during pregnancy, breastfeeding and having fewer siblings

Stability of continuously pumped atom lasers

A multimode model of a continuously pumped atom laser is shown to be unstable below a critical value of the scattering length. Above the critical scattering length, the atom laser reaches a steady state, the stability of which increases with pumping. Below this limit the laser does not reach a steady state. This instability results from the competition between gain and loss for the excited states of the lasing mode. It will determine a fundamental limit for the linewidth of an atom laser beam.Comment: 4 page

Differentiating Disclosure and Concealment in Measurement of Outness for Sexual Minorities: The Nebraska Outness Scale

Research on lesbian, gay, and bisexual (LGB) individuals has long examined outness, or openness about one’s sexual orientation, as an important predictor of health and well-being. The authors reconceptualized outness as a composite of two related but independent constructs: disclosure and concealment of sexual orientation. This conceptualization guided creation of the Nebraska Outness Scale (NOS), a 10-item measure with a concealment (NOS-C) and disclosure (NOS-D) subscale. The scale and subscales showed good internal reliability, discriminant, convergent, and predictive validity. As hypothesized, concealment showed a stronger relationship to mental health and well-being constructs than disclosure. Disclosure, but not concealment, also differed across sexual orientations with bisexual individuals reporting less disclosure and mostly gay/lesbian and gay/lesbian individuals reporting successively higher levels. The authors conclude that concealment and disclosure are separate constructs and that concealment may be more relevant to minority stress processes among LGB individuals and may provide a more comparable measure across sexual orientation categories. Further research is needed to validate the scale and to examine the role that outness plays in minority stress among LGB individuals

A Space of Transition: Rethinking Surrogates

The knowledge organization (KO) process of representing something identifiable typically involves creating a surrogate. The surrogate brings together the thing and the knowledge organization system (KOS). Therefore, we decided to focus on the surrogate and its role in the process of representation. In current practice KOS govern the creation of the surrogate. This something being represented is typically, but not necessarily, an information resource. It may also be artistic, tangible, spiritual, etc., knowledge organization systems meant to organize surrogates that represent something identifiable. A knowledge organization professional (KOP) selects what aspects of the thing to include in the representation. The knowledge organization experts/establishment (KOE) are responsible for the development of the context in which surrogates are created. The KOE are key drivers in determining process, and in developing and maintaining standards. Traditional practices are intended to ensure consistency and uniformity of interpretation and application across a range of physical and digital discourses. This context can be considered anew as postcolonial critic Homi Bhabha’s concept of the Third Space (1994)