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Replicate radiocarbon (14C) measurements of organic and inorganic control samples, with known Fraction Modern values in the range Fm = 0–1.5 and mass range 6 μg–2 mg carbon, are used to determine both the mass and radiocarbon content of the blank carbon introduced during sample processing and measurement in our laboratory. These data are used to model, separately for organic and inorganic samples, the blank contribution and subsequently “blank correct” measured unknowns in the mass range 25–100 μg. Data, formulas, and an assessment of the precision and accuracy of the blank correction are presented.
Recent commercialization of auxin herbicide–based weed control systems has led to increased off-target exposure of susceptible cotton cultivars to auxin herbicides. Off-target deposition of dilute concentrations of auxin herbicides can occur on cotton at any stage of growth. Field experiments were conducted at two locations in Mississippi from 2014 to 2016 to assess the response of cotton at various growth stages after exposure to a sublethal 2,4-D concentration of 8.3 g ae ha−1. Herbicide applications occurred weekly from 0 to 14 weeks after emergence (WAE). Cotton exposure to 2,4-D at 2 to 9 WAE resulted in up to 64% visible injury, whereas 2,4-D exposure 5 to 6 WAE resulted in machine-harvested yield reductions of 18% to 21%. Cotton maturity was delayed after exposure 2 to 10 WAE, and height was increased from exposure 6 to 9 WAE due to decreased fruit set after exposure. Total hand-harvested yield was reduced from 2,4-D exposure 3, 5 to 8, and 13 WAE. Growth stage at time of exposure influenced the distribution of yield by node and position. Yield on lower and inner fruiting sites generally decreased from exposure, and yield partitioned to vegetative or aborted positions and upper fruiting sites increased. Reductions in gin turnout, micronaire, fiber length, fiber-length uniformity, and fiber elongation were observed after exposure at certain growth stages, but the overall effects on fiber properties were small. These results indicate that cotton is most sensitive to low concentrations of 2,4-D during late vegetative and squaring growth stages.
Methods for identifying relevant policy impacts for valuation in benefit-cost analyses (BCAs) have received relatively little attention in academic research, applied policy analyses, and guidance documents. In this paper, we develop a systematic, transparent, and replicable process that draws upon information contained in records of Congressional hearings to identify relevant policy impacts for valuation in a BCA. Our approach involves classifying – and subsequently analyzing – statements from witnesses testifying in Congressional hearings on the topic of the BCA. By using Congressional hearings as the basis for our approach, we are identifying potential policy impacts from information provided during the very process the BCA is intended to inform. However, because this approach is quite resource-intensive and would be somewhat burdensome for agencies to implement, it may be best applied in the academic realm, with identified impacts resulting from such applications then made available to agency personnel for potential inclusion in BCAs. Using the case of the Glen Canyon Dam, we demonstrate the approach and its resulting improvements in the quality and transparency of the BCA it was intended to inform.
The introduction of auxin herbicide weed control systems has led to increased occurrence of crop injury in susceptible soybeans and cotton. Off-target exposure to sublethal concentrations of dicamba can occur at varying growth stages, which may affect crop response. Field experiments were conducted in Mississippi in 2014, 2015, and 2016 to characterize cotton response to a sublethal concentration of dicamba equivalent to 1/16X the labeled rate. Weekly applications of dicamba at 35 g ae ha−1 were made to separate sets of replicated plots immediately following planting until 14 wk after emergence (WAE). Exposure to dicamba from 1 to 9 WAE resulted in up to 32% visible injury, and exposure from 7 to 10 WAE delayed crop maturity. Exposure from 8 to 10 and 13 WAE led to increased cotton height, while an 18% reduction in machine-harvested yield resulted from exposure at 6 WAE. Cotton exposure at 3 to 9 WAE reduced the seed cotton weight partitioned to position 1 fruiting sites, while exposure at 3 to 6 WAE also reduced yield in position 2 fruiting sites. Exposure at 2, 3, and 5 to 7 WAE increased the percent of yield partitioned to vegetative branches. An increase in percent of yield partitioned to plants with aborted terminals occurred following exposure from 3 to 7 WAE and corresponded with reciprocal decreases in yield partitioned to positional fruiting sites. Minimal effects were observed on fiber quality, except for decreases in fiber length uniformity resulting from exposure at 9 and 10 WAE.
Five species of bivalves and two species of gastropods are described from late Selandian to earliest Thanetian wood-fall communities from the Katsuhira Formation in Urahoro Town, eastern Hokkaido, northern Japan. Three bivalves and two gastropods are new to science: Thyasira (Thyasira) oliveri Amano and Jenkins, new species, Astarte (Astarte) paleocenica Amano and Jenkins, new species, Poromya katsuhiraensis Amano and Jenkins, new species, Neverita majimai Amano and Jenkins, new species, and Biplica paleocenica Amano and Jenkins, new species. Poromya katsuhiraensis n. sp. and Neverita majimai n. sp. are the earliest records of their genus. Astarte paleocenica n. sp. is the last species before the genus disappeared from the northern Pacific region during the Eocene, only to reappear with the opening of the Bering Strait during the latest Miocene. Moreover, two bivalve species and one gastropod genus are Cretaceous relict forms: Propeamussium yubarense (Yabe and Nagao, 1928), Myrtea ezoensis (Nagao, 1938), and Biplica Popenoe, 1957. These species and other relict protobranch bivalves had wide geographical ranges in the deep sea during the Cretaceous, which helped them to survive the end-Cretaceous mass extinction. The chemosynthesis-based species Bathyacmaea? sp., Myrtea ezoensis, and Thyasira oliveri n. sp. were recovered, but small bathymodioline mussels have not been found. This confirms that the small deep-sea mussels did not appear in the wood-fall communities at least by the earliest Thanetian.
Four new species of the methane seep-inhabiting kalenterid bivalve genus Caspiconcha Kelly in Kelly et al., 2000 are described: Caspiconcha basquensis from the late Albian of northern Spain, C. yubariensis from the late Albian of northern Japan, C. raukumaraensis from the late Albian to mid-Cenomanian of New Zealand, and C. lastsamurai from the Campanian of northern Japan. The earliest confirmed record of the genus is known from the latest Jurassic. It reached its maximum diversity in the Albian and declined in diversity and abundance through the Late Cretaceous. The youngest species, C. lastsamurai, is currently known from a single specimen only.
We have developed and tested a wide-field photometer to detect extrasolar planet transits from the South Pole. The discovery of transiting planets for which masses can be measured by radial velocity is vital to constrain the models of planet formation and evolution. Short of going to space, the South Pole is the best site from which to carry out a such a survey. Based on results from the Doppler velocity surveys and the Vulcan transit search, we expect to detect 10 to 15 transiting planets in two years of operation at the South Pole.
Quasi-stationary distributions (QSDs) arise from stochastic processes that exhibit transient equilibrium behaviour on the way to absorption. QSDs are often mathematically intractable and even drawing samples from them is not straightforward. In this paper the framework of sequential Monte Carlo samplers is utilised to simulate QSDs and several novel resampling techniques are proposed to accommodate models with reducible state spaces, with particular focus on preserving particle diversity on discrete spaces. Finally, an approach is considered to estimate eigenvalues associated with QSDs, such as the decay parameter.
The Internet offers a number of advantages as a survey mode: low marginal cost per completed response, capabilities for providing respondents with large quantities of information, speed, and elimination of interviewer bias. Those seeking these advantages confront the problem of representativeness both in terms of coverage of the population and capabilities for drawing random samples. Two major strategies have been pursued commercially to develop the Internet as a survey mode. One strategy, used by Harris Interactive, involves assembling a large panel of willing respondents who can be sampled. Another strategy, used by Knowledge Networks, involves using random digit dialing (RDD) telephone methods to recruit households to a panel of Web-TV enabled respondents. Do these panels adequately deal with the problem of representativeness to be useful in political science research? The authors address this question with results from parallel surveys on global climate change and the Kyoto Protocol administered by telephone to a national probability sample and by Internet to samples of the Harris Interactive and Knowledge Networks panels. Knowledge and opinion questions generally show statistically significant but substantively modest difference across the modes. With inclusion of standard demographic controls, typical relational models of interest to political scientists produce similar estimates of parameters across modes. It thus appears that, with appropriate weighting, samples from these panels are sufficiently representative of the U.S. population to be reasonable alternatives in many applications to samples gathered through RDD telephone surveys.
Survey-based contingent valuation (CV) techniques are commonly used to value the potential effects of a policy change when market-based valuation of those effects is not possible. The results of these analyses are often intended to inform policy decisions, which are made within the context of formal policymaking institutions. These institutions are typically designed to reduce the large number of potential options for addressing any given policy problem to a binary choice between the continuation of current policy and a single, specified alternative. In this research we develop an approach for conducting CV exercises in a manner consistent with the decision structure typically faced by policymakers. The data generated from this approach allow for an estimate of willingness to pay (WTP) for a defined policy alternative, relative to leaving policy unchanged, which we argue is of direct interest to policymakers. We illustrate our approach within the context of policy governing the storage of used nuclear fuel in the United States. We value the policy option of constructing an interim storage facility relative to continuation of current policy, wherein used nuclear fuel is stored on-site at or near commercial nuclear generating plants. We close the paper with a discussion of the implications for future research and the role of CV in the policymaking process.
Gas-accepting ion sources for radiocarbon accelerator mass spectrometry (AMS) have permitted the direct analysis of CO2 gas, eliminating the need to graphitize samples. As a result, a variety of analytical instruments can be interfaced to an AMS system, processing time is decreased, and smaller samples can be analyzed (albeit with lower precision). We have coupled a gas chromatograph to a compact 14C AMS system fitted with a microwave ion source for real-time compound-specific 14C analysis. As an initial test of the system, we have analyzed a sample of fatty acid methyl esters and biodiesel. Peak shape and memory was better then existing systems fitted with a hybrid ion source while precision was comparable. 14C/12C ratios of individual components at natural abundance levels were consistent with those determined by conventional methods. Continuing refinements to the ion source are expected to improve the performance and scope of the instrument.
A new and unique radiocarbon accelerator mass spectrometry (AMS) facility has been constructed at the Woods Hole Oceanographic Institution. The defining characteristic of the new system is its large-gap optical elements that provide a larger-than-standard beam acceptance. Such a system is ideally suited for high-throughput, high-precision measurements of 14C. Details and performance of the new system are presented.
Compound specific radiocarbon measurements can be made instantaneously using a gas chromatograph (GC) combustion system coupled to a 14C AMS system fitted with a gas ion source. Samples below 10 μg C can be analyzed but the precision is reduced to 5–10% because of lower source efficiency. We modified our GC for CH4 and CO2 analysis and injected samples multiple times to sum data and increase precision. We attained a maximum precision of 0.6% for modern CO2 from 25 injections of 27 μg C and a background of ≃0.5% (40 kyr) for ancient methane. The 14C content of dissolved CO2 and CH4 in water samples collected at a deep-sea hydrothermal vent and a serpentine mud volcano was measured and the results for the vent sample are consistent with previously published data. Further experiments are required to determine a calibration and correction procedure to maximize accuracy.
The objective of this study was to report procedural characteristics and adverse events on the data collected in the IMproving Paediatric and Adult Congenital Treatment registry.
The IMproving Paediatric and Adult Congenital Treatment– registry is a catheterisation registry focussed on paediatric and adult patients with congenital heart disease who are undergoing diagnostic catheterisations and catheter-based interventions. This study reports procedural characteristics and adverse events of patients who have undergone selected catheterisation procedures from January, 2011 to June, 2013.
Demographic, clinical, procedural, and institutional data elements were collected at participating centres and entered via either a web-based platform or software provided by the American College of Cardiology-certified vendors, and were collected in a secure, centralised database. For the purpose of this study, procedures that were not classified as one of the ‘core’ IMproving Paediatric and Adult Congenital Treatment procedures originally chosen for additional data collection were identified and selected for further data analysis.
During the time frame of data collection, a total of 8021 cases were classified as other procedures and/or multiple procedures. The most commonly performed case types – isolated or in combination with other procedures – were right ventricular biopsy in 3433 (42.8%), conduit/MPA interventions in 979 (12.3%), and systemic pulmonary artery collateral occlusion in 601 (7.5%). For the whole cohort, adverse events of any severity occurred in 957 (12.0%) cases, whereas major adverse events occurred in 113 (1.4%) cases; six patients (0.1%) died in the catheterisation laboratory.
The IMproving Paediatric and Adult Congenital Treatment registry has provided important data on the frequency and spectrum of cardiac catheterisation procedures performed in the present era. For many procedures, more data and work are needed to identify more subtle differences between case categories, especially as it relates to the incidence of major adverse events, and to further develop a risk-adjustment methodology to allow equitable comparisons among institutions.
To report procedural characteristics and adverse events on data collected in the registry.
The IMPACT – IMproving Paediatric and Adult Congenital Treatment – Registry is a catheterisation registry of paediatric and adult patients with CHD undergoing diagnostic and interventional cardiac catheterisation. We are reporting the procedural characteristics and adverse events of patients undergoing diagnostic and interventional catheterisation procedures from January, 2011 to March, 2013.
Demographic, clinical, procedural, and institutional data elements were collected at the participating centres and entered via either a web-based platform or software provided by American College of Cardiology-certified vendors, and were collected in a secure, centralised database. Centre participation was voluntary.
During the time frame of data collection, 19,797 procedures were entered into the IMPACT Registry. Procedures were classified as diagnostic only (35.4%); one of six specific interventions (23.8%); other or multiple interventions (40.7%); and were further broken down into four age groups. Anaesthesia was used in 84.1% of diagnostic procedures and 87.8% of interventional ones. Adverse events occurred in 10.0% of diagnostic and 11.1% of interventional procedures.
The IMPACT Registry is gathering data to set national benchmarks for diagnostic and certain specific interventional procedures. We are seeing little differences in procedural characteristics or adverse events in diagnostic procedures compared with interventional procedures overall, but there is significant variation in adverse events amongst age categories. Risk stratification and patient acuity scores will be required for further analysis of these differences.
In our earlier work  microstructural evolution in tungsten under self-ion irradiation was investigated as a function of temperature and dose by in-situ 150 keV W+ ion irradiations on the IVEM-Tandem facility at Argonne National Laboratory (ANL). The present work focuses on the thermal stability of this damage. Thin foils of tungsten were irradiated at room temperature (R.T.) to fluences up to 1018 W+m-2 (∼ 1.0 dpa) and were then annealed in-situ for up to 120 min at temperatures between 300 and 800°C.
We found that: (1) loops with Burgers vectors ½ <111> and <100> coexist during annealing; (2) <100> is not a stable loop configuration above 300°C and the fraction of such loops decreased with increasing temperature and/or time; (3) changes in loop populations during annealing were very sensitive to temperature, but less sensitive to time. The majority of changes occurred within 15 min, and were associated with the loss of small (1-2 nm) dislocation loops. The origin of these trends is discussed by considering defect mobility and the energetics of defect configurations predicted by previous DFT calculations .