Oklahoma State University–Stillwater

About: Oklahoma State University–Stillwater is a education organization based out in Stillwater, Oklahoma, United States. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 18267 authors who have published 36743 publications receiving 1107500 citations. The organization is also known as: Oklahoma State University & OKState.

Wavelet packet feature extraction for vibration monitoring

Abstract: Condition monitoring of dynamic systems based on vibration signatures has generally relied upon Fourier-based analysis as a means of translating vibration signals in the time domain into the frequency domain. However, Fourier analysis provided a poor representation of signals well localized in time. In this case, it is difficult to detect and identify the signal pattern from the expansion coefficients because the information is diluted across the whole basis. The wavelet packet transform (WPT) is introduced as an alternative means of extracting time-frequency information from vibration signatures. The resulting WPT coefficients provide one with arbitrary time-frequency resolution of a signal. With the aid of statistical-based feature selection criteria, many of the feature components containing little discriminant information could be discarded, resulting in a feature subset having a reduced number of parameters without compromising the classification performance. The extracted reduced dimensional feature vector is then used as input to a neural network classifier. This significantly reduces the long training time that is often associated with the neural network classifier and improves its generalization capability.

Should heterogeneity be the basis for conservation? Grassland bird response to fire and grazing.

Abstract: In tallgrass prairie, disturbances such as grazing and fire can generate patchiness across the landscape, contributing to a shifting mosaic that presumably enhances biodiversity. Grassland birds evolved within the context of this shifting mosaic, with some species restricted to one or two patch types created under spatially and temporally distinct disturbance regimes. Thus, management-driven reductions in heterogeneity may be partly responsible for declines in numbers of grassland birds. We experimentally altered spatial heterogeneity of vegetation structure within a tallgrass prairie by varying the spatial and temporal extent of fire and by allowing grazing animals to move freely among burned and unburned patches (patch treatment). We contrasted this disturbance regime with traditional agricultural management of the region that promotes homogeneity (traditional treatment). We monitored grassland bird abundance during the breeding seasons of 2001-2003 to determine the influence of altered spatial heterogeneity on the grassland bird community. Focal disturbances of patch burning and grazing that shifted through the landscape over several years resulted in a more heterogeneous pattern of vegetation than uniform application of fire and grazing. Greater spatial heterogeneity in vegetation provided greater variability in the grassland bird community. Some bird species occurred in greatest abundance within focally disturbed patches, while others occurred in relatively undisturbed patches in our patch treatment. Henslow's Sparrow, a declining species, occurred only within the patch treatment. Upland Sandpiper and some other species were more abundant on recently disturbed patches within the same treatment. The patch burn treatment created the entire gradient of vegetation structure required to maintain a suite of grassland bird species that differ in habitat preferences. Our study demonstrated that increasing spatial and temporal heterogeneity of disturbance in grasslands increases variability in vegetation structure that results in greater variability at higher trophic levels. Thus, management that creates a shifting mosaic using spatially and temporally discrete disturbances in grasslands can be a useful tool in conservation. In the case of North American tallgrass prairie, discrete fires that capitalize on preferential grazing behavior of large ungulates promote a shifting mosaic of habitat types that maintain biodiversity and agricultural productivity.

Tolerance of mannitol-accumulating transgenic wheat to water stress and salinity.

Abstract: Previous work with model transgenic plants has demonstrated that cellular accumulation of mannitol can alleviate abiotic stress. Here, we show that ectopic expression of the mtlD gene for the biosynthesis of mannitol in wheat improves tolerance to water stress and salinity. Wheat ( Triticum aestivum L. cv Bobwhite) was transformed with the mtlD gene of Escherichia coli . Tolerance to water stress and salinity was evaluated using calli and T 2 plants transformed with (+mtlD) or without (−mtlD) mtlD . Calli were exposed to −1.0 MPa of polyethylene glycol 8,000 or 100 mm NaCl. T 2 plants were stressed by withholding water or by adding 150 mm NaCl to the nutrient medium. Fresh weight of −mtlD calli was reduced by 40% in the presence of polyethylene glycol and 37% under NaCl stress. Growth of +mtlD calli was not affected by stress. In −mtlD plants, fresh weight, dry weight, plant height, and flag leaf length were reduced by 70%, 56%, 40%, and 45% compared with 40%, 8%, 18%, and 29%, respectively, in +mtlD plants. Salt stress reduced shoot fresh weight, dry weight, plant height, and flag leaf length by 77%, 73%, 25%, and 36% in −mtlD plants, respectively, compared with 50%, 30%, 12%, and 20% in +mtlD plants. However, the amount of mannitol accumulated in the callus and mature fifth leaf (1.7–3.7 μmol g −1 fresh weight in the callus and 0.6–2.0 μmol g −1 fresh weight in the leaf) was too small to protect against stress through osmotic adjustment. We conclude that the improved growth performance of mannitol-accumulating calli and mature leaves was due to other stress-protective functions of mannitol, although this study cannot rule out possible osmotic effects in growing regions of the plant.

Navigating the tip of the genomic iceberg: Next-generation sequencing for plant systematics.

Abstract:  Premise of the study: Just as Sanger sequencing did more than 20 years ago, next-generation sequencing (NGS) is poised to revolutionize plant systematics By combining multiplexing approaches with NGS throughput, systematists may no longer need to choose between more taxa or more characters Here we describe a genome skimming (shallow sequencing) approach for plant systematics  Methods: Through simulations, we evaluated optimal sequencing depth and performance of single-end and paired-end short read sequences for assembly of nuclear ribosomal DNA (rDNA) and plastomes and addressed the effect of divergence on reference-guided plastome assembly We also used simulations to identify potential phylogenetic markers from low-copy nuclear loci at different sequencing depths We demonstrated the utility of genome skimming through phylogenetic analysis of the Sonoran Desert clade (SDC) of Asclepias (Apocynaceae)  Key results: Paired-end reads performed better than single-end reads Minimum sequencing depths for high quality rDNA and plastome assemblies were 40 × and 30 × , respectively Divergence from the reference signifi cantly affected plastome assembly, but relatively similar references are available for most seed plants Deeper rDNA sequencing is necessary to characterize intragenomic polymorphism The low-copy fraction of the nuclear genome was readily surveyed, even at low sequencing depths Nearly 160 000 bp of sequence from three organelles provided evidence of phylogenetic incongruence in the SDC  Conclusions: Adoption of NGS will facilitate progress in plant systematics, as whole plastome and rDNA cistrons, partial mitochondrial genomes, and low-copy nuclear markers can now be effi ciently obtained for molecular phylogenetics studies