Plasma Dynamics

Contains research objectives and reports on two research projects

Influence of light exposure on horizontal transmission of Salmonella typhimurium in weaned pigs

The objective of the following experiment was to examine the effect of light exposure on horizontal transmission of Salmonella typhimurium in weaned pigs. Twenty crossbred pigs (average BW = 15 kg) were housed in isolation rooms (10 pigs/room) and randomly assigned to one of two lighting regimes. Low (8 h light, 16 h dark) or High (16 h light, 8 h dark). Pigs were adjusted to their respective lighting treatments for six days and on the seventh day, two randomly selected pigs/room orally inoculated with 5 ml of tryptic soy broth containing 18 x 108 cfu Salmonella typhimurium/ml. Rectal swabs were collected from each pig daily over the next eight days for direct plating and plating following 24-h enrichment. On day nine, following inoculation of the seeder pigs, all pigs were euthanized and necropsied. Luminal contents were collected from the ileum, colon, cecum and rectum (quantification and qualification of inoculated strain) and tissue samples collected from the above gut segments as well as the tonsils, ileo-cecal lymph nodes, spleen and liver (qualification only)

Plasma Dynamics

Contains reports on two research projects.WADC Contract AF33(616)-3984Servomechanisms Research Laborator

Methane Mitigation:Methods to Reduce Emissions, on the Path to the Paris Agreement

The atmospheric methane burden is increasing rapidly, contrary to pathways compatible with the goals of the 2015 United Nations Framework Convention on Climate Change Paris Agreement. Urgent action is required to bring methane back to a pathway more in line with the Paris goals. Emission reduction from “tractable” (easier to mitigate) anthropogenic sources such as the fossil fuel industries and landfills is being much facilitated by technical advances in the past decade, which have radically improved our ability to locate, identify, quantify, and reduce emissions. Measures to reduce emissions from “intractable” (harder to mitigate) anthropogenic sources such as agriculture and biomass burning have received less attention and are also becoming more feasible, including removal from elevated-methane ambient air near to sources. The wider effort to use microbiological and dietary intervention to reduce emissions from cattle (and humans) is not addressed in detail in this essentially geophysical review. Though they cannot replace the need to reach “net-zero” emissions of CO2, significant reductions in the methane burden will ease the timescales needed to reach required CO2 reduction targets for any particular future temperature limit. There is no single magic bullet, but implementation of a wide array of mitigation and emission reduction strategies could substantially cut the global methane burden, at a cost that is relatively low compared to the parallel and necessary measures to reduce CO2, and thereby reduce the atmospheric methane burden back toward pathways consistent with the goals of the Paris Agreement

Studying patterns of use of transport modes through data mining - Application to U.S. national household travel survey data set

Data collection activities related to travel require large amounts of financial and human resources to be conducted successfully. When available resources are scarce, the information hidden in these data sets needs to be exploited, both to increase their added value and to gain support among decision makers not to discontinue such efforts. This study assessed the use of a data mining technique, association analysis, to understand better the patterns of mode use from the 2009 U.S. National Household Travel Survey. Only variables related to self-reported levels of use of the different transportation means are considered, along with those useful to the socioeconomic characterization of the respondents. Association rules potentially showed a substitution effect between cars and public transportation, in economic terms but such an effect was not observed between public transportation and nonmotorized modes (e.g., bicycling and walking). This effect was a policy-relevant finding, because transit marketing should be targeted to car drivers rather than to bikers or walkers for real improvement in the environmental performance of any transportation system. Given the competitive advantage of private modes extensively discussed in the literature, modal diversion from car to transit is seldom observed in practice. However, after such a factor was controlled, the results suggest that modal diversion should mainly occur from cars to transit rather than from nonmotorized modes to transi

Effects of antibiotic-suppelmented media on recovery of enterobacteria

The frequency at which Salmonella typhimurium (ST) and Escherichia coli were recovered from tryptic soy agar (TSA), brilliant green agar (BGA) and MacConkey agar (MAC) alone or supplemented with 2 and 16 µg kanamycin and 0.25 and 2 µg enrofloxacin was investigated

30 days wild: development and evaluation of a large-scale nature engagement campaign to improve well-being

There is a need to increase people’s engagement with and connection to nature, both for human well-being and the conservation of nature itself. In order to suggest ways for people to engage with nature and create a wider social context to normalise nature engagement, The Wildlife Trusts developed a mass engagement campaign, 30 Days Wild. The campaign asked people to engage with nature every day for a month. 12,400 people signed up for 30 Days Wild via an online sign-up with an estimated 18,500 taking part overall, resulting in an estimated 300,000 engagements with nature by participants. Samples of those taking part were found to have sustained increases in happiness, health, connection to nature and pro-nature behaviours. With the improvement in health being predicted by the improvement in happiness, this relationship was mediated by the change in connection to nature

Isolation of Salmonella spp. and bacteriophage active against Salmonella spp. from commercial swine

Bacteriophage are viruses that prey on bacteria and may be a potential strategy to reduce foodborne pathogemc bactena in the gastromtestlnal tract of food animals Phages are fairly common in the gastrointestinal microbial ecosystem of mammals, but the incidence is unknown. If phage are to be an intervention strategy, we must understand their role in the microbial ecology of the gut. From a regulatory perspective, knowing incidence of phage is crucial. Therefore the current study was designed to determine the incidence of phage active against Salmonella spp in the feces of commercial finishing swine in the United States. Fecal samples (n=60) were collected from each of six commercial swine finishing operations. Samples were collected from 10 randomly selected pens throughout each operation. Total number of fecal samples collected in this study was n=360 Salmonella spp were found in 66% of the fecal samples Salmonella spp. were isolated from only 2 farms and the serotypes represented were Schwarzengrund, Anatum, Ohio and Heidelberg Bacteriophages were isolated from fecal sample through 2 parallel methods, 1) initlal enrichment in Salmonella Typhimunum, or 2) initial ennchment in E. colt B (a strain very sensitive to phages), followed by direct spot-testing against Salmonella Typhimurium Bacteriophages active against Salmonella Typhimunum were isolated from 1.1% 4/360) of the individual fecal samples when initially enriched in Salmonella Typhimurium, but E coli S-killing phages were 1solated from 43.8% (158/360) of the fecal samples but only 2 of these Isolates were capable of k1ll1ng Salmonella Typhimunum. Our results mdicate that bactenophage capable of killing Salmonella Typh1murium are fairly w1despread across commercial swine production facilities but may be present at relatively low populat1ons These results md1cate that phage (predator) populations may vary along w1th Salmonella (prey) populations and that phage could potentially be used as a food safety pathogen reduction strategy

The local adsorption structure of benzene on Si(001)-(2 × 1): a photoelectron diffraction investigation

Scanned-energy mode C 1s photoelectron diffraction has been used to investigate the local adsorption geometry of benzene on Si(001) at saturation coverage and room temperature. The results show that two different local bonding geometries coexist, namely the 'standard butterfly' (SB) and 'tilted bridge' (TB) forms, with a composition of 58 ± 29% of the SB species. Detailed structural parameter values are presented for both species including Si–C bond lengths. On the basis of published measurements of the rate of conversion of the SB to the TB form on this surface, we estimate that the timescale of our experiment is sufficient for achieving equilibrium, and in this case our results indicate that the difference in the Gibbs free energy of adsorption, ΔG(TB)−ΔG(SB), is in the range −0.023 to +0.049 eV. We suggest, however, that the relative concentration of the two species may also be influenced by a combination of steric effects influencing the kinetics, and a sensitivity of the adsorption energies of the adsorbed SB and TB forms to the nature of the surrounding benzene molecules