Assessment and Development of Cold Temperature Germination Tolerance in Oat and Hard Red Spring Wheat

Oat (Avena Sativa) and hard red spring wheat (HRSW; Triticum aestivum L.) are both spring planted cereal crops that yield best when planted early in the spring. These crops would benefit from improvements in cold temperature germination tolerance (CTGT) by allowing them faster and more uniform germination and emergence early in the spring. This study aimed to (i) evaluate germination in oat genotypes over a range of sub-optimal temperatures and (ii) establish a methodology for selection of hard red spring wheat for CTGT. Seed samples of ten different oat genotypes were evaluated for CTGT in a germination chamber at the temperatures 5, 7, 9, 11, 13, and 15°C. Temperature was held constant for two weeks for all temperatures, and three and four weeks for the lowest temperatures five and seven degrees Celsius. Results show that time and temperature, as well as their interactions affect germination significantly at reduced temperatures. Genotypes Horsepower and Colt germinated the best across the range of temperatures used. HRSW genotypes were planted on towels in a germination chamber, and the first and last seeds to germinate were transplanted into greenhouse pots. Four genotypes were used: Forefront, SD4011/Barlow, SD4330, and SD4189/SD3997. The first seeds to germinate were successfully transplanted into the greenhouse without difficulty, so breeders should be able to use this methodology to perform selections on HRSW to improve CTGT

Restoration success of backfilling canals in coastal Louisiana marshes

The need for effective marsh restoration techniques in Louisiana is a pressing issue as the state continues to lose coastal wetlands. Returning spoil banks to canals, known as backfilling , is an attractive restoration option because it restores marsh, prevents future wetland loss, and is cost effective. The direct conversion of marsh to canals and spoil banks accounted for over 22% of Louisiana\u27s wetland loss from 1930 to 1990, and the indirect losses associated with canal dredging are even larger. The restoration success of 30 canals, backfilled twenty years ago, was examined in this study and compared to restoration success shortly after backfilling. Ultimately, the success of backfilling was controlled by the amount of spoil returned to the canal and the position of the canal in the marsh. Up to 95% of the spoil area was restored to marsh when the spoil banks were adequately removed, but only 5% of the spoil area was restored at sites where spoil removal was poor. Restoration of organic matter, bulk density, and water content of the former spoil areas was also constrained by the adequacy of spoil removal. Backfilling restored 80% of the organic matter and 94% of the bulk density and water content after twenty years at sites where spoil was properly removed. The plant species on the former spoil areas often did not match those of the surrounding marsh, and the differences were directly correlated with the amount of spoil removed. Canals backfilled in areas of more intact marsh showed greater restoration success than canals backfilled in highly degraded marshes. This study indicates that the benefits of backfilling continue to increase over time, although complete restoration will take longer than twenty years, particularly for soils. Improving the completeness of spoil removal, coupled with appropriate site selection, could speed up the restoration process and enhance the success of future backfilling projects

Benthic communities in the northern Gulf of Mexico hypoxic area: potential prey for demersal fish

Bottom-water hypoxia (≤2 mg O2 l-1) usually occurs on an annual basis on the Louisiana/Texas continental shelf from mid-May through mid-September over a large area (up to 20,000 km2 in mid-summer). The effects of hypoxia on the benthic infauna (potential prey) for demersal fish were examined, because changes in optimal diet can lead to negative impacts on growth and reproduction. Benthic samples were taken in three areas (inshore and offshore out of hypoxia and in the hypoxic area) during August 2003. Samples were also taken monthly from September 2003 to October 2004 at a fixed station (C6B) where summer hypoxia occurs consistently. The mean abundance of the benthic infauna in the three summer areas were not significantly different indicating similar prey abundances found in the study area. Diverse infaunal communities exist offshore of the hypoxic zone with similar species composition compared to the inshore but different compared to the hypoxic area. An abundance of benthos at the surface was not found at the summer 2003 hypoxic stations; therefore there was not an abundance of available prey at the surface. However, benthos migrated toward the surface at station C6B in June and July 2004 during hypoxia, providing an increase of prey at the surface compared to other months. During the spring months, the infaunal community was more diverse and abundant compared to the post hypoxic months (August, September, and October), which suggests fewer and less diverse potential prey in the fall for demersal predators. The most abundant prey items for demersal fish in the study area were polychaetes and secondarily molluscs. The benthic community abundances during the summer 2003 and 2004 were not expected and may be due to the storm events in summer 2003 and shorter duration of hypoxia in summer 2004

Microphytobenthos of the northern Gulf of Mexico hypoxic area and their role in oxygen dynamics

The presence or absence of microphytobenthos on the seafloor provides clues about whether benthic oxygen evolution contributes significantly to the oxygen budget of the hypoxic area in the northern Gulf of Mexico. Hypoxia (oxygen \u3c 2 mg l-1) creates inadequate concentrations of dissolved oxygen to support most organisms, such as fish, shrimp and crabs, and occurs over large areas of the Louisiana continental shelf from spring through summer in most years. Oxygen production by benthic autotrophs may offset a decline in oxygen concentrations if there is a functioning community and sufficient light. I sampled three stations (14, 20 and 23 m depths) ~ 100 km west of the Mississippi River over three hypoxic annual cycles (2006 – 2008), and 11 stations along a 14 - 20 m contour on the shelf in late-July in 2006, 2007 and 2008. I used microscopy and high-performance liquid chromatography to estimate the biomass and composition of phytoplankton and microphytobenthos. The potential seasonal oxygen production was estimated in 2007 and 2008 by incubating coupled light/dark sediment cores and bottom water from two stations. The sediment community (cells \u3e 3 um) differed from those in the water column and were frequently benthic pennate diatoms and filamentous cyanobacteria (58-88% seasonally and 1-99% in mid-summer). The concentration of microphytobenthic biomass was usually \u3c 2.0 ug g dry sed-1, and various biotic parameters were influenced by light at the seafloor. Declines in dissolved oxygen over a seasonal cycle in 2007 and 2008 were affected more by the initial dissolved oxygen concentration than by the presence of microphytobenthos that could generate oxygen. The sediment (1.2 - 27.3 mmol O2 m-2 d-1, n = 97) and bottom-water (1.1 - 17.5 mmol m-2 d-1, n = 23) oxygen consumption rates were within the range of the few previously-reported data. This work adds to these data and also provides the only sediment oxygen consumption rates at fixed sites over seasonal time scales. These results provide critical input to three-dimensional, physical-biological models of oxygen dynamics for this hypoxic area

Restoration Success Of Backfilling Canals In Coastal Louisiana Marshes

The need for effective marsh restoration techniques in Louisiana is a pressing issue as the state continues to lose coastal wetlands. Returning spoil banks to canals, known as backfilling, is an attractive restoration option because it restores marsh, prevents future wetland loss, and is cost effective. The restoration of 30 canals backfilled 20 years ago was examined in this study and compared to restoration success 5 and 10 years after backfilling. Ultimately, the success of backfilling was controlled by the amount of spoil returned to the canal and the position of the canal in the marsh. Up to 95% of the spoil area was restored to marsh when the spoil banks were adequately removed, but only 5% of the spoil area was restored at sites where spoil removal was poor. Restoration of organic matter, bulk density, water content, and plant communities of the former spoil areas was also constrained by the adequacy of spoil removal. Backfilling restored up to 90% of the organic matter, 92% of the bulk density, and 93% of the water content after 20 years at sites where spoil was properly removed. Canals backfilled in areas of intact marsh showed greater restoration success than canals backfilled in highly degraded marshes. This study indicates that the benefits of backfilling continue to increase over time, although complete restoration will take longer than 20 years. Improving the completeness of spoil removal, coupled with appropriate site selection, could speed up the restoration process and enhance the success of future backfilling projects

Development of a sensor for the continuous measurement of oil concentration in a refrigeration system

Shortcomings in the present standard method of determining the circulating oil concentration in a refrigeration system have led to the current research, wherein a continuous, in-line method of measuring the flowing oil concentration is sought;A literature survey and preliminary property measurements examined properties of oil-refrigerant mixtures that could be measured to infer the oil concentration in the liquid line of a refrigeration system. Four measurement methods were selected for development into oil concentration sensors: a vibrating U-tube densimeter, a new type of in-line viscometer, a prototype acoustic velocity probe, and an optical fiber refractometer;A flow loop capable of simulating a wide variety of liquid-line conditions was constructed for the testing and calibration of the oil concentration sensors. Performance tests of the densimeter, viscometer, and acoustic velocity sensor were conducted over an oil concentration range of 0 to 30 weight-percent for 150 SUS naphthenic oil/R-12, 150 SUS naphthenic oil/R-22, and 150 SUS alkylbenzene oil/R-502 mixtures. The temperatures in the flow loop test section during the performance tests were varied from 70 to 120 F and the pressure was maintained to provide approximately 3 F subcooling. Performance testing of the refractometer was not completed because of severe probe temperature sensitivity and poor repeatability;The performance test results were statistically analyzed to determine the oil concentration measurement uncertainty. The three sensors tested were found to attain the desired ±1 weight-percent uncertainty under a variety of conditions. Application guidelines are presented for the use of the densimeter, viscometer, and acoustic velocity as oil concentration sensors

Laboratory Studies of Ice Formation Pathways from Ammonium Sulfate Particles

Cirrus clouds are composed of ice particles and their formation pathways have been studied extensively in the laboratory. The ability of ammonium sulfate particles to act as nuclei for cirrus clouds has been of particular importance because of their ubiquitous presence in the upper troposphere. The results of past laboratory experiments of homogeneous ice nucleation from ammonium sulfate particles show a wide range of freezing conditions. In the present study, a flow tube apparatus equipped with Fourier transform infrared spectroscopy was used to reexamine these discrepancies. It was found that when ammonium sulfate particles were preconditioned at 100% relative humidity (RH) prior to experimentation, the particles began to freeze at conditions predicted by the homogeneous ice nucleation model developed by Koop et al. (2000). If the particles were not preconditioned at 100% RH, some froze at warmer temperatures and lower ice saturation ratios than predicted by Koop et al. (2000). It is hypothesized that a population of effloresced particles affected freezing conditions for particles that were not preconditioned at 100% RH

Health status of infants and children from the Bronze Age tomb at Tell Abraq, United Arab Emirates

Tell Abraq is significant because it is the largest prehistoric site on the southern coast of the Arabian Gulf. It was strategically important as an ancient port, regionally surrounded by large political centers. Commingled remains were located in a small tomb (6 m) used for a 200 year period (2200-2000 BC). The site was continually occupied from the 3rd millennium BC up to the 1st century AD. In the tomb were minimally 286 adults and 127 subadults. What is extraordinary is the number of pre-term (3rd trimester) infants (n=28, 22%), neonates (n=12, 9%), and infants under 2 years (n=46, 36%). The collection also yielded many children aged 2 to 5 years (n=32, 25%). This abundance of very young children is more startling in comparison to the very low number of subadults aged 6-18 (n=9, 7%). Differential preservation and burial practices of older children do not appear to be reasons for this low number. We have reported elsewhere that the adult portion of the population appears relatively robust and well-represented across age and sex categories. Analysis using radiography, thin-sections, metric data, and paleopathology demonstrates that while there was some suffering from infection and failure to thrive among the subadults (as suggested by poor cortical maintenance at the expense of growth in length), frequencies are not high enough to explain what placed premature and newly born infants and toddlers at risk. Cultural norms such as consanguinity, marriage and pregnancy at a young age, and benign neglect may be underlying factors contributing to poor infant outcomes