4,873 research outputs found
The Asymmetric Effects of Changes in Price and Income on Energy and Oil Demand
This paper estimates the effects on energy and oil demand of changes in income and oil prices, for 96 of the world's largest countries, in per-capita terms. We examine three important issues: the asymmetric effects on demand of increases and decreases in oil prices; the asymmetric effects on demand of increases and decreases in income; and the different speeds of demand adjustment to changes in price and in income. Its main conclusions are the following: (1) OECD demand responds much more to increases in oil prices than to decreases; ignoring this asymmetric price response will bias downward the estimated income elasticity; (2) demand's response to income decreases in many non-OECD countries is not necessarily symmetric to its response to income increases; ignoring this asymmetric income response will bias the estimated income elasticity; (3) the speed of demand adjustment is faster to changes in income than to changes in price; ignoring this difference will bias upward the estimated response to income changes. Using correctly specified equations for energy and oil demand, the long-run elasticity for increases in income is about 0.55 for OECD energy and oil, and 1.0 or higher for Non-OECD Oil Exporters, Income Growers and perhaps all Non-OECD countries. These income elasticity estimates are significantly higher than current estimates used by the US Department of Energy. Our estimates for the OECD countries are also higher than those estimated recently by Schmalensee-Stoker-Judson (1998) and Holtz-Eakin and Selden (1995), who ignore the asymmetric effects of prices on demand. Higher income elasticities, of course, will increase projections of energy and oil demand, and of carbon dioxide emissions.ENERGY DEMAND; OIL DEMAND; ASYMMETRY; IRREVERSIBILITY; INCOME ELASTICITY
What do faculty and students really think about e-books?
Purpose - The purpose of this article is to report on a large-scale survey that was carried Out to assess academic users' awareness, perceptions and existing levels of use of e-books. The survey also seeks to find out about the purposes to which electronic books were put, and to obtain an understanding of the most effective library marketing and communication channels.Design/methodology/approach - An e-mail invitation to participate in the survey was distributed to all UCL staff and students (approximately 27,000) in November 2006, and 1,818 completions were received, an effective response rate of at least 6.7 per cent. Statistical analyses were carried out on the data using Software Package for Social Sciences (SPSS).Findings - The survey findings point to various ways in which user uptake and acceptance of e-books may be encouraged. Book discovery behaviour, a key issue for publishers and librarians in both print and electronic environments, emerges as a critical focus for service delivery and enhancement.Originality/value - The survey is part of an action research project, CIBER's SuperBook, that will further investigate the issues raised in this initial benchmarking survey using deep log analysis and qualitative methods. The paper partly fills the gap in the literature on e-books which has mainly focused on usage and not the users
Diamond chemical vapor deposition on optical fibers for fluorescence waveguiding
A technique has been developed for depositing diamond crystals on the
endfaces of optical fibers and capturing the fluorescence generated by
optically active defects in the diamond into the fiber. This letter details the
diamond growth on optical fibers and transmission of fluorescence through the
fiber from the nitrogen-vacancy (N-V) color center in diamond. Control of the
concentration of defects incorporated during the chemical vapor deposition
(CVD) growth process is also demonstrated. These are the first critical steps
in developing a fiber coupled single photon source based on optically active
defect centers in diamond.Comment: 10 pages, 3 figure
An Appraisal of FOPIM Fast-converging Perturbation Method
Appraisal of first order perturbation iteration fast converging metho
Are there spurious temperature trends in the United States Climate Division database
The United States (U.S.) Climate Division data set is commonly used in applied climatic studies in the United States. The divisional averages are calculated by including all available stations within a division at any given time. The averages are therefore vulnerable to shifts in average station location or elevation over time, which may introduce spurious trends within these data. This paper examines temperature trends within the 15 climate divisions of New England, comparing the NCDC\u27s U.S. Divisional Data to the U.S. Historical Climate Network (USHCN) data. Correlation and multiple regression revealed that shifts in latitude, longitude, and elevation have affected the quality of the NCDC divisional data with respect to the USHCN. As a result, there may be issues with regard to their use in decadal- to century-scale climate change studies
The health and wellbeing of adults working in early childhood education
This article reports the results of a survey of 168 New Zealand early childhood workers and describes their health status, behaviours and concerns. The respondents included 73 childcare teachers, 58 kindergarten teachers and 37 home-based educators. Although 92 per cent of respondents reported that they had good or excellent health, statistically significant differences were found between the groups for days absent because of illness, accidental injuries, job-related stress and ergonomic aspects of their work. All groups reported an increase in various physical symptoms since working with children, in particular backaches, muscle strain and fatigue. One-quarter of respondents experienced an illness related to their work with children during the past year, most commonly respiratory and gastrointestinal illnesses. The study alerts early childhood education employers to the importance of managing health issues such as workload and stress, occupational injuries, the provision of an ergonomically healthy work environment and adequate conditions of employment
Elastic properties of hydrogenated graphene
There exist three conformers of hydrogenated graphene, referred to as chair-,
boat-, or washboard-graphane. These systems have a perfect two-dimensional
periodicity mapped onto the graphene scaffold, but they are characterized by a
orbital hybridization, have different crystal symmetry, and otherwise
behave upon loading. By first principles calculations we determine their
structural and phonon properties, as well as we establish their relative
stability. Through continuum elasticity we define a simulation protocol
addressed to measure by a computer experiment their linear and nonlinear
elastic moduli and we actually compute them by first principles. We argue that
all graphane conformers respond to any arbitrarily-oriented extention with a
much smaller lateral contraction than the one calculated for graphene.
Furthermore, we provide evidence that boat-graphane has a small and negative
Poisson ratio along the armchair and zigzag principal directions of the carbon
honeycomb lattice (axially auxetic elastic behavior). Moreover, we show that
chair-graphane admits both softening and hardening hyperelasticity, depending
on the direction of applied load.Comment: submitted on Phys.Rev.
Nonlinear elasticity of monolayer graphene
By combining continuum elasticity theory and tight-binding atomistic
simulations, we work out the constitutive nonlinear stress-strain relation for
graphene stretching elasticity and we calculate all the corresponding nonlinear
elastic moduli. Present results represent a robust picture on elastic behavior
of one-atom thick carbon sheets and provide the proper interpretation of recent
experiments. In particular, we discuss the physical meaning of the effective
nonlinear elastic modulus there introduced and we predict its value in good
agreement with available data. Finally, a hyperelastic softening behavior is
observed and discussed, so determining the failure properties of graphene.Comment: 4 page
A highly efficient two level diamond based single photon source
An unexplored diamond defect centre which is found to emit stable single
photons at a measured rate of 1.6 MHz at room temperature is reported. The
novel centre, identified in chemical vapour deposition grown diamond crystals,
exhibits a sharp zero phonon line at 734 nm with a full width at half maximum
of ~ 4 nm. The photon statistics confirm the center is a single emitter and
provides direct evidence of the first true two-level single quantum system in
diamond.Comment: 3 pages, 4 figure
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