552 research outputs found
Continuing field efficacy of norbormide against both Rattus rattus (ship rats) and Rattus norvegicus (Norway rats)
Norbormide is a uniquely selective rat toxicant for Rattus species, with rats being 100- to 150-fold more sensitive to norbormide toxicity than most other mammals and birds. Previously we reported that on completion of a 10-year program of targeted fundamental and applied synthetic chemistry and toxicology, taste aversion associated with this compound had been overcome. In 2020-2022, trials have been successfully completed on poultry farms with Norway rats and larger scale field trials were undertaken targeting ship rats using 1% norbormide paste baits. Firstly, the efficacy of norbormide-containing paste baits targeting rat infestations on poultry farms was proven with a 100% reduction of Norway rat populations on three different farms. Secondly, 100% reduction in ship rat abundance was achieved at two large field test sites; and no reduction was achieved at the untreated control site. These larger field trials are described in depth in this publication. Plans are progressing to complete product development and registration
Space station common module network topology and hardware development
Conceptual space station common module power management and distribution (SSM/PMAD) network layouts and detailed network evaluations were developed. Individual pieces of hardware to be developed for the SSM/PMAD test bed were identified. A technology assessment was developed to identify pieces of equipment requiring development effort. Equipment lists were developed from the previously selected network schematics. Additionally, functional requirements for the network equipment as well as other requirements which affected the suitability of specific items for use on the Space Station Program were identified. Assembly requirements were derived based on the SSM/PMAD developed requirements and on the selected SSM/PMAD network concepts. Basic requirements and simplified design block diagrams are included. DC remote power controllers were successfully integrated into the DC Marshall Space Flight Center breadboard. Two DC remote power controller (RPC) boards experienced mechanical failure of UES 706 stud-mounted diodes during mechanical installation of the boards into the system. These broken diodes caused input to output shorting of the RPC's. The UES 706 diodes were replaced on these RPC's which eliminated the problem. The DC RPC's as existing in the present breadboard configuration do not provide ground fault protection because the RPC was designed to only switch the hot side current. If ground fault protection were to be implemented, it would be necessary to design the system so the RPC switched both the hot and the return sides of power
Biological Interactions in Grassland Soils and Productivity
This paper describes research on interactions between grassland plant species and soil microorganisms. Both parasitic and symbiotic microorganisms modify nutrient transfers between plants and soil. Experiments are described in which nematode infection of clover increased nitrogen transfer to companion ryegrass plants. Infection of clover enhanced activity of soil bacterial and fungal communities. Legume genotypes differing only in responses to symbionts (rhizobium and arbuscular mycorrhizal fungi) and pathogens are being developed for studies of gene expression during establishing and functional symbioses. Such plants can be used in experiments as defined perturbations that will provide information on the interactions and functions of symbiotic and pathogenic microorganisms. Such studies, related to field observations, may have value for defining biological attributes of sustainable grassland soil systems
Diphacinone and coumatetralyl persistence in deer and implications for wildlife management
Eason, C.T., Murphy, E., Ross, J.G., Hix, S., Arthur, D., MacMorran, D., Broome, K., Fairweather, A
Squirrels Do the Math: Flight Trajectories in Eastern Gray Squirrels (Sciurus carolinensis)
Animals are under strong selective pressures to make correct decisions when attempting to escape an approaching predator, and not surprisingly many studies have shown that animals adjust their flight initiation behavior in response to risk. However, we have a poor understanding of animals' capability to select an appropriate flight trajectory. We investigated whether eastern gray squirrels would adjust their flight trajectory based on the relative locations of the squirrel, the approaching threat, and potential refuges. We used a person running toward a focal squirrel (N = 122) as the threat and considered the three trees nearest the squirrel and taller than 8 m to be potential refuges. Squirrels were strongly affected by the angle (θ) formed by the locations of person, squirrel, and the three nearest trees. A squirrel was less likely to run to the nearest tree (Tree 1) when θ1 was relatively acute, but also less likely to run to Tree 1 when θ2 was obtuse, making Tree 2 a more attractive refuge. A squirrel was more likely to run to Tree 1 if it was close and if Tree 2 was relatively far. Subtle differences in the effects of θ1 vs. θ2 on squirrel refuge choice support the idea that squirrels prefer a nearby refuge. Squirrels were more likely to select Trees 2 and 3 rather than Tree 1 only when θ2 was obtuse (105°). In contrast, most squirrels chose to run to Tree 1 when θ1 was >65°; thus squirrels were more likely to choose Tree 1 even when doing so required running at least partly toward the approaching threat. The decisions made by focal squirrels provide evidence that this species' assessment of risk is highly nuanced. A great deal of variation has been reported in responses to predators within species. While part of the variation may be due to strategic unpredictability on the part of the prey, part of it may also be due to differences in flight trajectory and refuge preferences that have not been well-studied
The importance of Icelandic ice sheet growth and retreat on mantle CO2 flux
Climate cycles may significantly affect the eruptive behavior of terrestrial volcanoes due to pressure changes caused by glacial loading, which raises the possibility that climate change may modulate CO2 degassing via volcanism. In Iceland, magmatism is likely to have been influenced by glacial activity. To explore if deglaciation therefore impacted CO2 flux we coupled a model of glacial loading over the last ∼120 ka to melt generation and transport. We find that a nuanced relationship exists between magmatism and glacial activity. Enhanced CO2 degassing happened prior to the main phase of late‐Pleistocene deglaciation, and it is sensitive to the duration of the growth of the ice sheet entering into the LGM, as well as the rate of ice loss. Ice sheet growth depresses melting in the upper mantle, creating a delayed pulse of CO2 out‐gassing as the magmatic system recovers from the effects of loading
Secondary user relations in emerging mobile computing environments
Mobile technologies are enabling access to information in diverse environ.ments, and are exposing a wider group of individuals to said technology. Therefore, this paper proposes that a wider view of user relations than is usually considered in information systems research is required. Specifically, we examine the potential effects of emerging mobile technologies on end-‐user relations with a focus on the ‘secondary user’, those who are not intended to interact directly with the technology but are intended consumers of the technology’s output. For illustration, we draw on a study of a U.K. regional Fire and Rescue Service and deconstruct mobile technology use at Fire Service incidents. Our findings provide insights, which suggest that, because of the nature of mobile technologies and their context of use, secondary user relations in such emerging mobile environments are important and need further exploration
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A Physically Based Correlation of Irradiation-Induced Transition Temperature Shifts for RPV Steels
The reactor pressure vessels (RPVs) of commercial nuclear power plants are subject to embrittlement due to exposure to high-energy neutrons from the core, which causes changes in material toughness properties that increase with radiation exposure and are affected by many variables. Irradiation embrittlement of RPV beltline materials is currently evaluated using Regulatory Guide 1.99 Revision 2 (RG1.99/2), which presents methods for estimating the shift in Charpy transition temperature at 30 ft-lb (TTS) and the drop in Charpy upper shelf energy (ΔUSE). The purpose of the work reported here is to improve on the TTS correlation model in RG1.99/2 using the broader database now available and current understanding of embrittlement mechanisms. The USE database and models have not been updated since the publication of NUREG/CR-6551 and, therefore, are not discussed in this report. The revised embrittlement shift model is calibrated and validated on a substantially larger, better-balanced database compared to prior models, including over five times the amount of data used to develop RG1.99/2. It also contains about 27% more data than the most recent update to the surveillance shift database, in 2000. The key areas expanded in the current database relative to the database available in 2000 are low-flux, low-copper, and long-time, high-fluence exposures, all areas that were previously relatively sparse. All old and new surveillance data were reviewed for completeness, duplicates, and discrepancies in cooperation with the American Society for Testing and Materials (ASTM) Subcommittee E10.02 on Radiation Effects in Structural Materials. In the present modeling effort, a 10% random sample of data was reserved from the fitting process, and most aspects of the model were validated with that sample as well as other data not used in calibration. The model is a hybrid, incorporating both physically motivated features and empirical calibration to the U.S. power reactor surveillance data. It contains two terms, corresponding to the best-understood radiation damage features, matrix damage and copper-rich precipitates, although the empirical calibration will ensure that all other damage processes that are occurring are also reflected in those terms. Effects of material chemical composition, product form, and radiation exposure are incorporated, such that all effects are supported by findings of statistical significance, physical understanding, or comparison with independent data from controlled experiments, such as the Irradiation Variable (IVAR) Program. In most variable effects, the model is supported by two or three of these different forms of evidence. The key variable trends, such as the neutron fluence dependence and copper-nickel dependence in the new TTS model, are much improved over RG1.99/2 and are well supported by independent data and the current understanding of embrittlement mechanisms. The new model includes the variables copper, nickel, and fluence that are in RG1.99/2, but also includes effects of irradiation temperature, neutron flux, phosphorus, and manganese. The calibrated model is a good fit, with no significant residual error trends in any of the variables used in the model or several additional variables and variable interactions that were investigated. The report includes a chapter summarizing the current understanding of embrittlement mechanisms and one comparing the IVAR database with the TTS model predictions. Generally good agreement is found in that quantitative comparison, providing independent confirmation of the predictive capability of the TTS model. The key new insight in the TTS modeling effort, that flux effects are evident in both low (or no) copper and higher copper materials, is supported by the IVAR data. The slightly simplified version of the TTS model presented in Section 7.3 of this report is recommended for applications
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