453 research outputs found
The impact of tritium contamination of air humidity and ground water on the tritium concentration of tissue water in plants studied under real conditions
Derivation and validation of alcohol phenotypes in a college population : a motivational/developmental approach
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on July 29, 2009)Thesis (Ph. D.) University of Missouri-Columbia 2008.Numerous typologies of alcoholics have been proposed, dating back to the 1850s. However, many of these typologies have categorized alcoholics on distal and/or static etiological factors. In this study, longitudinal data collected on nine occasions over four years were used to derive and validate a typology based on a more proximal etiological factor (i.e., drinking motives) and change over time in heavy alcohol involvement. Data were taken from an incoming undergraduate sample ([nu] = 3,720 at baseline). Mixture models of heavy alcohol involvement, coping motives, and enhancement motives, resulted in seven groups of individuals with distinct on patterns over time on these variables. Membership in any class other than the group characterized by the lowest levels of heavy alcohol use and drinking motives was predicted by several common risk factors (i.e., extraversion, symptoms of conduct disorder and drug dependence, Greek membership, and perceived peer alcohol involvement), as well as risk factors related specifically to levels of heavy drinking (i.e., male sex and parental education) or drinking motives (i.e., neuroticism and conscientiousness) in each class. Use of typological approaches that incorporate both alcohol consumption as well as motivational factors may aid in the identification of at-risk drinkers and inform specialized prevention and treatment efforts.Includes bibliographical reference
Two-axis bend measurement with Bragg gratings in multicore optical fiber
We describe what is to our knowledge the first use of fiber Bragg gratings written into three separate cores of a multicore fiber for two-axis curvature measurement. The gratings act as independent, but isothermal, fiber strain gauges for which local curvature determines the difference in strain between cores, permitting temperature-independent bend measurement. (C) 2003 Optical Society of America
LIBS experiments for quantitative detection of retained fuel
Abstract Laser Induced Breakdown Spectroscopy (LIBS) provides chemical information from atomic and ionic plasma emissions generated by laser vaporization of a sample. At the ENEA research center, in collaboration with IPPLM, an equipment has been set up to qualitatively and quantitatively determine the chemical composition of impurities deposited on Plasma Facing Components (PFC). The strength of the LIBS, for its capability of light elements detection, is fully exploited to determine the deuterium content since this element can be considered as the best choice proxy for tritium; the latter being is of great importance in assessing safe conditions to assure the continuous operation in nuclear fusion tokamak. Here we present the results of the Double Pulse LIBS (DP-LIBS) probing of deuterated samples with the simultaneous optical detection by medium-resolution and high-resolution spectrometer. Deuterium emission at 656.1 nm has been detected then the elemental composition has been quantified by applying the Calibration Free (CF) approach. The obtained results demonstrate that the DP-LIBS technique combined with CF analysis is suitable for the quantitative determination of tritium content inside the PFCs of next fusion devices like ITER
Identification of Myotropic Neuropeptides from the Brain and Corpus Cardiacum-Corpus Allatum Complex of the Beetle, Zophobas atratus
The neuropeptide profiles of the two major neuro-endocrinological organs, brain and retrocerebral complex corpus cardiacum-corpus allatum (CC/CA) of adult beetles, Zophobas atratus Fabricius (Coleoptera:Tenebrionidae) were analyzed by a combination of high performance liquid chromatography (HPLC) and matrix-assisted laser desorption ionization time of flight tandem mass spectrometry (MALDI TOF/TOF MS). The homological semi-isolated heart bioassay was used to screen HPLC fractions for myotropic activity in tissues, revealing several cardiostimulatory and cardioinhibitory factors from both the brain and CC/CA. Analysis of HPLC fractions by MALDI-TOF MS identified seven mass ions that could be assigned to other known peptides: leucomyosuppressin (LMS), Tribolium castaneum pyrokinin 2, sulfakinin 1, myoinhibitory peptide 4, a truncated NVP-like peptide, Tenebrio molitor AKH and crustacean cardioactive peptide. In addition, two novel peptides, myosuppressin (pEDVEHVFLRFa), which differs from LMS by one amino acid (E for D at position 4) and pyrokinin-like peptide (LPHYTPRLa) were also identified. To establish cardioactive properties of some of the identified peptides, chemical synthesis was carried out and their activities were tested using the heart bioassay
Protons accelerated in the target normal sheath acceleration regime by a femtosecond laser
Advanced targets based on thin films of graphene oxide covered by metallic layers have been irradiated at high laser intensity (∼1019 W/cm2) with 40 fs laser pulses to investigate the forward ion acceleration in the target normal sheath acceleration regime. A time-of-flight technique was employed with silicon-carbide detectors and ion collectors as fast on-line plasma diagnostics. At the optimized conditions of the laser focus position with respect to the target surface was measured the maximum proton energy using Au metallic films. A maximum proton energy of 2.85 MeV was measured using the Au metallization of 200 nm. The presence of graphene oxide facilitates the electron crossing of the foil minimizing the electron scattering and increasing the electric field driving the ion acceleration. The effect of plasma electron density control using the graphene oxide is presented and discussed
Mode-Dependent Loss and Gain: Statistics and Effect on Mode-Division Multiplexing
In multimode fiber transmission systems, mode-dependent loss and gain
(collectively referred to as MDL) pose fundamental performance limitations. In
the regime of strong mode coupling, the statistics of MDL (expressed in
decibels or log power gain units) can be described by the eigenvalue
distribution of zero-trace Gaussian unitary ensemble in the small-MDL region
that is expected to be of interest for practical long-haul transmission.
Information-theoretic channel capacities of mode-division-multiplexed systems
in the presence of MDL are studied, including average and outage capacities,
with and without channel state information.Comment: 22 pages, 8 figure
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