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Search Results: 1 - 10 of 158175 matches for " Eric B. Norman "
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Additional experimental evidence against a solar influence on nuclear decay rates
Eric B. Norman
Physics , 2012,
Abstract: Conflicting results from two experiments studying the decay of Cl-36 point to instrumental artifacts rather than a solar influence being responsible for variations in measured counting rates.
Observations of Fallout from the Fukushima Reactor Accident in San Francisco Bay Area Rainwater
Eric B. Norman, Christopher T. Angell, Perry A. Chodash
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024330
Abstract: We have observed fallout from the recent Fukushima Dai-ichi reactor accident in samples of rainwater collected in the San Francisco Bay area. Gamma ray spectra measured from these samples show clear evidence of fission products – 131,132I, 132Te, and 134,137Cs. The activity levels we have measured for these isotopes are very low and pose no health risk to the public.
Seaborg's Plutonium?
Eric B. Norman,Keenan J. Thomas,Kristina E. Telhami
Physics , 2014,
Abstract: Passive x-ray and gamma-ray analysis was performed on UC Berkeley's EH&S Sample S338. The object was found to contain Pu-239 and no other radioactive isotopes. The mass of Pu-239 contained in this object was determined to be 2.0 +- 0.3 micrograms. These observations are consistent with the identification of this object being the 2.77-microgram plutonium oxide sample described by Glenn Seaborg and his collaborators as the first sample of Pu-239 that was large enough to be weighed.
Report on Gamma-Ray Analysis of Seaweed Samples from Naturespirit Herbs LLC
Eric B. Norman,Keenan Thomas,Pedro Guillaumon,Alan R. Smith
Physics , 2014,
Abstract: Five seaweed samples from Naturespirit Herbs LLC were counted using low-background high-resolution gamma-ray detectors to search for evidence of contamination from the Fukushima reactor accident. No evidence of Cs-134 was observed in any of the samples. Very low levels of Cs-137 were observed and are attributed to fallout from atmospheric nuclear weapons testing. However, these levels of Cs-137 are small compared to the levels of the naturally occurring K-40 observed from these seaweed samples.
Antineutrino Monitoring of Thorium Reactors to Promote Nuclear Security
Oluwatomi A. Akindele,Adam Bernstein,Eric B. Norman
Physics , 2015,
Abstract: Various groups have demonstrated that antineutrino monitoring can be successful in assessing the plutonium content in water-cooled nuclear reactors for nonproliferation applications. New reactor designs and concepts incorporate nontraditional fuels types and chemistry. Understanding how these properties affect the antineutrino emission from a reactor can extend the applicability of antineutrino monitoring. Thorium molten salt reactors (MSR) breed U-233, that if diverted constitute a direct use material as defined by the International Atomic Energy Agency (IAEA). The antineutrino spectrum from the fission of U-233 has been estimated for the first time, and the feasibility of detecting the diversion of 8 kg of U-233, within a 30 day timeliness goal has been evaluated. The antineutrino emission from a thorium reactor operating under normal conditions is compared to a diversion scenario at a 25 meter standoff by evaluating the daily antineutrino count rate and the energy spectrum of the detected antineutrinos. It was found that the diversion of a significant quantity of U-233 could not be detected within the IAEA timeliness detection goal using either tests. A rate based analysis exceeded the timeliness goal by 17 days, while a spectral based analysis exceeds this goal by 154 days.
Virus-Host and CRISPR Dynamics in Archaea-Dominated Hypersaline Lake Tyrrell, Victoria, Australia
Joanne B. Emerson,Karen Andrade,Brian C. Thomas,Anders Norman,Eric E. Allen,Karla B. Heidelberg,Jillian F. Banfield
Archaea , 2013, DOI: 10.1155/2013/370871
Abstract: The study of natural archaeal assemblages requires community context, namely, a concurrent assessment of the dynamics of archaeal, bacterial, and viral populations. Here, we use filter size-resolved metagenomic analyses to report the dynamics of 101 archaeal and bacterial OTUs and 140 viral populations across 17 samples collected over different timescales from 2007–2010 from Australian hypersaline Lake Tyrrell (LT). All samples were dominated by Archaea (75–95%). Archaeal, bacterial, and viral populations were found to be dynamic on timescales of months to years, and different viral assemblages were present in planktonic, relative to host-associated (active and provirus) size fractions. Analyses of clustered regularly interspaced short palindromic repeat (CRISPR) regions indicate that both rare and abundant viruses were targeted, primarily by lower abundance hosts. Although very few spacers had hits to the NCBI nr database or to the 140 LT viral populations, 21% had hits to unassembled LT viral concentrate reads. This suggests local adaptation to LT-specific viruses and/or undersampling of haloviral assemblages in public databases, along with successful CRISPR-mediated maintenance of viral populations at abundances low enough to preclude genomic assembly. This is the first metagenomic report evaluating widespread archaeal dynamics at the population level on short timescales in a hypersaline system. 1. Introduction As the most abundant and ubiquitous biological entities, viruses influence host mortality and community structure, food web dynamics, and geochemical cycles [1, 2]. In order to better characterize the potential influence that viruses have on archaeal evolution and ecology, it is important to understand the coupled dynamics of viruses and their archaeal hosts in natural systems. Although previous studies have demonstrated dynamics in virus-host populations, most of these studies have focused on bacterial hosts, often restricted to targeted groups of virus-host pairs, and little is known about archaeal virus-host dynamics in natural systems. Community-scale virus-host analyses have often been based on low-resolution measurements of the whole community, relying on techniques such as denaturing gradient gel electrophoresis (DGGE), pulsed-field gel electrophoresis (PFGE), and microscopic counts (e.g., [3–5]). One exception is a study that examined viral and microbial dynamics through single read-based metagenomic analyses in four aquatic environments, including an archaea-dominated hypersaline crystallizer pond [6]. In that work, it was proposed
An Adaptive Physical Activity Intervention for Overweight Adults: A Randomized Controlled Trial
Marc A. Adams, James F. Sallis, Gregory J. Norman, Melbourne F. Hovell, Eric B. Hekler, Elyse Perata
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082901
Abstract: Background Physical activity (PA) interventions typically include components or doses that are static across participants. Adaptive interventions are dynamic; components or doses change in response to short-term variations in participant's performance. Emerging theory and technologies make adaptive goal setting and feedback interventions feasible. Objective To test an adaptive intervention for PA based on Operant and Behavior Economic principles and a percentile-based algorithm. The adaptive intervention was hypothesized to result in greater increases in steps per day than the static intervention. Methods Participants (N = 20) were randomized to one of two 6-month treatments: 1) static intervention (SI) or 2) adaptive intervention (AI). Inactive overweight adults (85% women, M = 36.9±9.2 years, 35% non-white) in both groups received a pedometer, email and text message communication, brief health information, and biweekly motivational prompts. The AI group received daily step goals that adjusted up and down based on the percentile-rank algorithm and micro-incentives for goal attainment. This algorithm adjusted goals based on a moving window; an approach that responded to each individual's performance and ensured goals were always challenging but within participants' abilities. The SI group received a static 10,000 steps/day goal with incentives linked to uploading the pedometer's data. Results A random-effects repeated-measures model accounted for 180 repeated measures and autocorrelation. After adjusting for covariates, the treatment phase showed greater steps/day relative to the baseline phase (p<.001) and a group by study phase interaction was observed (p = .017). The SI group increased by 1,598 steps/day on average between baseline and treatment while the AI group increased by 2,728 steps/day on average between baseline and treatment; a significant between-group difference of 1,130 steps/day (Cohen's d = .74). Conclusions The adaptive intervention outperformed the static intervention for increasing PA. The adaptive goal and feedback algorithm is a “behavior change technology” that could be incorporated into mHealth technologies and scaled to reach large populations. Trial Registration ClinicalTrials.gov NCT01793064
Cosmogenic-neutron activation of TeO2 and implications for neutrinoless double-beta decay experiments
Barbara S. Wang,Eric B. Norman,Nicholas D. Scielzo,Alan R. Smith,Keenan J. Thomas,Stephen A. Wender
Physics , 2015, DOI: 10.1103/PhysRevC.92.024620
Abstract: Flux-averaged cross sections for cosmogenic-neutron activation of natural tellurium were measured using a neutron beam containing neutrons of kinetic energies up to $\sim$800 MeV, and having an energy spectrum similar to that of cosmic-ray neutrons at sea-level. Analysis of the radioisotopes produced reveals that 110mAg will be a dominant contributor to the cosmogenic-activation background in experiments searching for neutrinoless double-beta decay of 130Te, such as CUORE and SNO+. An estimate of the cosmogenic-activation background in the CUORE experiment has been obtained using the results of this measurement and cross-section measurements of proton activation of tellurium. Additionally, the measured cross sections in this work are also compared with results from semi-empirical cross-section calculations.
A study on the nature of the peculiar supergiant HD101584
Eric J. Bakker,Henny J. G. L. M. Lamers,L. B. F. M. Waters,Christoffel Waelkens,Norman R. Trams,Hans van Winckel
Physics , 1995,
Abstract: We present a study of low- and high-resolution ultraviolet, high-resolution optical CAT/CES spectra and ultraviolet, optical and infrared photometry of the peculiar supergiant HD101584. From the photometry we learn that the ultraviolet and optical energy distribution cannot be fitted in a consistent way and we need a model in which the UV and optical energy distribution are formed by different gas. The Geneva photometry is best fitted to a B9II Kurucz model, Teff=12000+-1000K and log g=3.0 +-1.0, with an extinction of E(B-V)=0.49+-0.05. The observed spectral features in the spectrum of HD101584 are classified in eight different categories based on the velocity, shape of profile and the identification. The high-excitation HeI(chi=20.87eV), NII(chi=18.40eV), CII (chi=14.39eV) and NI (chi=10.29eV) optical absorption lines are formed in the photosphere of a late B-star (e.g. B8-9I-II). These absorption lines show radial velocity variations which are attributed to binary motion, with the secondary being a
Detection of C2, CN, and NaID absorption in the AGB remnant of HD56126
Eric J. Bakker,L. B. F. M. Waters,Henny J. G. L. M. Lamers,Norman R. Trams,Frank L. A. Van der Wolf
Physics , 1995,
Abstract: We present the detection of molecular absorption lines in the optical spectrum of the post-AGB star HD56126. The C2 Phillips A^{1}\Pi_{u}-X^{1}\Sigma^{+}_{g} (1,0), (2,0), and (3,0); Swan d^{3}\Pi_{g}-a^{3}\Pi_{u} (0,0) and (1,0); and CN Red system A^{2}\Pi-X^{2}\Sigma^{+} (1,0), (2,0), (3,0), and (4,0) bands have been identified. From the identification of the molecular bands we find an expansion velocity of 8.5+-0.6 kms independent of excitation condition or molecular specie. On the basis of the expansion velocity, rotational temperatures, and molecular column densities we argue that the line-forming region is the AGB remnant. This is in agreement with the expansion velocity derived from the CO lines. We find column densities of log N_C2=15.3+-0.3 cm-2 and log N_CN=15.5+-0.3 cm-2, and rotational temperatures of T_rot=242+-20 K and T_rot=24+-5 K respectively for C2 and CN. By studying molecular line absorption in optical spectra of post-AGB stars we have found a new tracer of the AGB remnant. From comparison with the results of CO and IR observations it is possible to obtain information on non-spherical behavior of the AGB remnant. Using different molecules with different excitation conditions it should be possible to study the AGB remnant as a function of the distance to the star, and thus as a function of the evolutionary status of the star on the AGB.
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