10,243 research outputs found
Local Solutions for Generic Multidimensional Resonant Wave Conversion
In more than one spatial dimension, resonant linear conversion from one wave
type to another can have a more complex geometry than the familiar 'avoided
crossing' of one-dimensional problems. In previous work we have shown that
helical ray shapes are generic in a mathematical sense. Here we briefly
describe how the local field structure can be computed.Comment: 4 pages, to appear in the AIP Proceedings of the 15th Topical
Conference on RF Power in Plasma
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Removal of heteroatoms and metals from crude oils by bioconversion processes
The objective of this Cooperative research and Development Agreement project between Oak Ridge National Laboratory (ORNL) and Baker Performance Chemicals (BPC), Chevron, Energy BioSystems, Exxon, UNOCAL and Texaco is to investigate the biological desulfurization of crude oil. Biological removal of organic sulfur from crude oil offers an attractive alternative to conventional thermochemical treatment due to the mild operating conditions afforded by the biocatalyst. In order for biodesulfurization to realize commercial success, reactors must be designed which allow for sufficient liquid/liquid and gas/liquid mass transfer while simultaneously reducing operating costs. To this end we have been developing advanced bioreactors for biodesulfurization and have been studying their performance using both actual crude oil as well as more easily characterized model systems. This CRADA was originally established to be a 3 year program, but was extended to 5 years due to continuing interest. Because of business restructuring, UNOCAL, whose activities focused upon the supply and analysis of crude oil samples, was unable to continue its participation in the CRADA. Hence this report is designed to cover only LTNOCAL`s contribution to the CRADA as other aspects of the research are not yet complete. Experiments investigating the biological oxidative desulfurization of crude oil demonstrated that while dibenzothiophene like structures were readily degraded (>90% in 48 h) this desulfurization had minimal impact upon the total sulfur in the crude oil. This is because these structures represent less than 1% of the total sulfur found in the crude. Additional research is needed investigating sulfur speciation in crude oil with increased efforts upon broadening the sulfur specificity of the biocatalyst
Inferring individual attributes from search engine queries and auxiliary information
Internet data has surfaced as a primary source for investigation of different
aspects of human behavior. A crucial step in such studies is finding a suitable
cohort (i.e., a set of users) that shares a common trait of interest to
researchers. However, direct identification of users sharing this trait is
often impossible, as the data available to researchers is usually anonymized to
preserve user privacy. To facilitate research on specific topics of interest,
especially in medicine, we introduce an algorithm for identifying a trait of
interest in anonymous users. We illustrate how a small set of labeled examples,
together with statistical information about the entire population, can be
aggregated to obtain labels on unseen examples. We validate our approach using
labeled data from the political domain.
We provide two applications of the proposed algorithm to the medical domain.
In the first, we demonstrate how to identify users whose search patterns
indicate they might be suffering from certain types of cancer. In the second,
we detail an algorithm to predict the distribution of diseases given their
incidence in a subset of the population at study, making it possible to predict
disease spread from partial epidemiological data
Chaos in Spin Clusters: Quantum Invariants and Level Statistics
The energy‐level sequence, whose spacings distribution is the most frequently invoked indicator of quantum chaos, can be derived (for systems with two degrees of freedom) from a two‐dimensional representation of quantum invariants by projection. In this representation, such properties of level sequences as effective randomness in integrable models and level repulsion in nonintegrable models can be more directly interpreted in terms of physical properties. In integrable models, anharmonicities convert quasiperiodic level sequences into effectively random sequences
V-V Bond-Length Fluctuations in Vox
We report a significantly stronger suppression of the phonon contribution to
the thermal conductivity in VOx than can be accounted for by disorder of the 16
% atomic vacancies present in VO. Since the transition from localized to
itinerant electronic behavior is first-order and has been shown to be
characterized by bond-length fluctuations in several transition-metal oxides
with the perovskite structure, we propose that cooperative V-V bond-length
fluctuations play a role in VO similar to the M-O bond-length fluctuations in
the perovskites. This model is able to account for the strong suppression of
the thermal conductivity, the existence of a pseudogap confirmed by
thermoelectric power, an anomalously large Debye-Waller factor, the temperature
dependence of the magnetic susceptibility, and the inability to order atomic
vacancies in VO.Comment: 5 pages, 5 figure
Secondary Sex Ratio among Women Exposed to Diethylstilbestrol in Utero
BACKGROUND. Diethylstilbestrol (DES), a synthetic estrogen widely prescribed to pregnant women during the mid-1900s, is a potent endocrine disruptor. Previous studies have suggested an association between endocrine-disrupting compounds and secondary sex ratio. METHODS. Data were provided by women participating in the National Cancer Institute (NCI) DES Combined Cohort Study. We used generalized estimating equations to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the relation of in utero DES exposure to sex ratio (proportion of male births). Models were adjusted for maternal age, child's birth year, parity, and cohort, and accounted for clustering among women with multiple pregnancies. RESULTS. The OR for having a male birth comparing DES-exposed to unexposed women was 1.05 (95% CI, 0.95-1.17). For exposed women with complete data on cumulative DES dose and timing (33%), those first exposed to DES earlier in gestation and to higher doses had the highest odds of having a male birth. The ORs were 0.91 (95% C, 0.65-1.27) for first exposure at ≥ 13 weeks gestation to < 5 g DES; 0.95 (95% CI, 0.71-1.27) for first exposure at ≥ 13 weeks to ≥ 5 g; 1.16 (95% CI, 0.96-1.41) for first exposure at < 13 weeks to < 5 g; and 1.24 (95% CI, 1.04-1.48) for first exposure at < 13 weeks to ≥ 5 g compared with no exposure. Results did not vary appreciably by maternal age, parity, cohort, or infertility history. CONCLUSIONS. Overall, no association was observed between in utero DES exposure and secondary sex ratio, but a significant increase in the proportion of male births was found among women first exposed to DES earlier in gestation and to a higher cumulative dose.National Cancer Institute (N01-CP-21168, N01-CP-51017, N01-CP-01289
Advancing the Evidence Base of Sport for Development: A New Open-Access, Peer-Reviewed Journal
We are pleased to release the first edition of the Journal of Sport for Development (JSFD) and we would like to take this opportunity to briefly describe its origins and objectives. In doing so, we endeavour to clarify for researchers, implementers, funders and policy-makers how we believe JSFD fits into the expanding sport for development (SFD) landscape. It is widely accepted that the United Nations International Year of Sport and Physical Education (IYSPE) in 2005 was an advocacy success and sparked a mass expansion in the SFD sector.1 This built on several previous international resolutions that recognised recreational play as a human right and emphasised the social potential of sport.2-9 Over the last decade, SFD has enjoyed widespread and international growth, in terms of resources, constituents, and public awareness.10 During this period several entities have attempted to define and demarcate the SFD sector. We believe that establishing a common definition is a critical step towards unifying a diverse range of stakeholders, many of which separately articulate the role of sport for social change and peace. However, we prefer to view these areas as integral parts of the sector and have adapted a previously described broad and inclusive definition for SFD
Classical Spin Clusters: Integrability and Dynamical Properties
A pair of exchange‐coupled classical spins with biaxial exchange and single‐site anisotropy represents a Hamiltonian system with two degrees of freedom for which the integrability question is nontrivial. We have found that such a system is completely integrable if the model parameters satisfy a certain condition. For the integrable cases, the second integral of the motion (in addition to the Hamiltonian), which guarantees integrability, is determined explicitly. It can be reconstructed numerically by means of time averages of dynamical variables over all trajectories. In the nonintegrable cases, the existence of the time averages is still guaranteed, but they no longer define an analytic invariant, and their determination is subject to long‐time anomalies. Our numerical calculation of time averages for two lines of initial conditions reveals a number of interesting features of such nonanalytic invariants
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