On velocity structure functions and the spherical vortex model for isotropic turbulence

We investigate a stochastic model for homogeneous, isotropic turbulence based on Hill's spherical vortex. This is an extension of the method of Synge and Lin [Trans. R. Soc. Can. 37, 45 (1943)], to the calculation of higher even-order velocity structure functions. Isotropic turbulence is represented by a homogeneous distribution of eddies, each modeled by a spherical vortex. The cascade process of eddy breakdown is incorporated into the statistical model through an average over an assumed log-normal distribution of vortex radii. We calculate the statistical properties of the model, in particular order-n velocity structure functions defined by rank-n tensors for the ensemble average of a set of incremental differences in velocity components. We define Di[centered ellipsis]s = , where denotes the ensemble average. Specifically Dij, Dijkl, and the longitudinal component of Dijklmn are calculated directly from the spherical vortex ensemble. Matching the longitudinal components of Dij and Dijkl with experimental results fixes two independent model parameters. The lateral and mixed components of Dijkl and the longitudinal component of Dijklmn are then model predictions

The Sulzer Hip Replacement Recall Crisis: A Patient\u27s Perspective

This case discusses a product recall that resulted from a manufacturing defect and the degree to which the company distributed accurate and timely information to affected patients. More specifically, the case examines the crisis communication of Sulzer Orthopedics and its efforts to negotiate the interests of various stakeholders, while limiting liability. Written from the perspective of a patient, the case raises interesting questions regarding organizational duties related to product liability. It also provides valuable insights into how organizational communication may have both short- and long-term effects on its relationship with patients and physicians, among others

Proton Transfer Reaction-Mass Spectrometry measurements of propylene glycol and diethylene glycol: preliminary results

Atmospheric volatile organic compounds (VOCs) are precursors of fine particulate matter anground-level ozone, both of which threaten the public health and are regulated by the U.S. EPA.. Due to the decrease in emissions from traditional transportation vehicles and power plants in the last four decades, volatile chemical products (VCPs) have become an emerging contributor to VOC emissions in urban atmosphere. These VCPs are typically found in household products as inactive ingredients, including cleaning agents, aerosol sprays, personal/hygienic care products, printer ink, pesticides, etc. Once these products are used, the VCPs volatilize and participate in reactions that form ground-level ozone and fine particulate matter. Despite their prevalence in our daily lives, these VCPs and their contribution to VOC emissions remain understudied and uncharacterized. This study aims to develop analytical methods for measuring and quantifying two VCPs using a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS). PTR-ToF-MS can provide real time VOC concentration measurements in ambient air. The quantification of VCPs and their mass analogues will allow for their detection in these ambient air samples. We focus on characterizing measurements of propylene glycol and diethylene glycol, which are commonly found in VCPs and have some of the highest chemical production volumes. We will present the preliminary results for their instrument sensitivities, fragmentation pathways, potential interferences, and humidity dependencies. We will discuss how altering various instrument parameters can improve these sensitivities and explore the optimal conditions for the atmospheric measurements of these species using PTR-ToF-MS

Egg-laying substrate selection for optimal camouflage by quail

Camouflage is conferred by background matching and disruption, which are both affected by microhabitat [1]. However, microhabitat selection that enhances camouflage has only been demonstrated in species with discrete phenotypic morphs [2 and 3]. For most animals, phenotypic variation is continuous [4 and 5]; here we explore whether such individuals can select microhabitats to best exploit camouflage. We use substrate selection in a ground-nesting bird (Japanese quail, Coturnix japonica). For such species, threat from visual predators is high [6] and egg appearance shows strong between-female variation [7]. In quail, variation in appearance is particularly obvious in the amount of dark maculation on the light-colored shell [8]. When given a choice, birds consistently selected laying substrates that made visual detection of their egg outline most challenging. However, the strategy for maximizing camouflage varied with the degree of egg maculation. Females laying heavily maculated eggs selected the substrate that more closely matched egg maculation color properties, leading to camouflage through disruptive coloration. For lightly maculated eggs, females chose a substrate that best matched their egg background coloration, suggesting background matching. Our results show that quail “know” their individual egg patterning and seek out a nest position that provides most effective camouflage for their individual phenotyp

Activity And Localization Of Maltodextrin Binding Site Mutants Of Glycogen Synthase In Saccharomyces Cerevisiae

Mentor: Wayne A. WilsonGlycogen is a glucose polymer formed by the enzyme glycogen synthase and is used in many organisms to store chemical energy. Saccharomyces cerevisiae (baker’s yeast) was used to study the activity and localization of glycogen synthase. Genes GSY1 and GSY2 encode glycogen synthase. GSY2 is responsible for the formation of Gsy2p, whose action accounts for ~90% of glycogen synthase activity; the remainder of total glycogen synthase activity stems from Gsy1p. Because glycogen synthase binds to glycogen, it can be used to determine glycogen localization. Glycogen synthase can appear in distinct patterns throughout the cell. Gsy2p has been shown to be regulated by phosphorylation. Phosphorylation of Gsy2p leads to inactivation of the enzyme, a decrease in glycogen storage, and a more localized pattern of glycogen synthase. Conversely, lowering the phosphorylation state of Gsy2p results in increased glycogen production and delocalization of glycogen synthase throughout the cell. Glucose-6-P (glucose-6-phosphate) activates glycogen synthase regardless of its phosphorylation state. We obtained a set of plasmids from a collaborator, encoding Gsy2p mutated at sites believed to be involved with maltodextrin binding. Maltodextrin is a chain of 20 or fewer dextrose molecules with α (1→4) glycosidic bonds. A protein sequence involved in maltodextrin binding likely would also bind to glycogen. Our task was to discover the localization pattern shown by the maltodextrin binding site mutants of glycogen synthase using a GFP tag on GSY2. The goal of this study was to determine the 16 effects of Gsy2p maltodextrin binding mutants on glycogen synthase activity, localization, and glycogen accumulation

Cell cycle correlated genes dictate the prognostic power of breast cancer gene lists

<p>Abstract</p> <p>Background</p> <p>Numerous gene lists or "classifiers" have been derived from global gene expression data that assign breast cancers to good and poor prognosis groups. A remarkable feature of these molecular signatures is that they have few genes in common, prompting speculation that they may use distinct genes to measure the same pathophysiological process(es), such as proliferation. However, this supposition has not been rigorously tested. If gene-based classifiers function by measuring a minimal number of cellular processes, we hypothesized that the informative genes for these processes could be identified and the data sets could be adjusted for the predictive contributions of those genes. Such adjustment would then attenuate the predictive function of any signature measuring that same process.</p> <p>Results</p> <p>We tested this hypothesis directly using a novel iterative-subtractive approach. We evaluated five gene expression data sets that sample a broad range of breast cancer subtypes. In all data sets, the dominant cluster capable of predicting metastasis was heavily populated by genes that fluctuate in concert with the cell cycle. When six well-characterized classifiers were examined, all contained a higher than expected proportion of genes that correlate with this cluster. Furthermore, when the data sets were globally adjusted for the cell cycle cluster, each classifier lost its ability to assign tumors to appropriate high and low risk groups. In contrast, adjusting for other predictive gene clusters did not impact their performance.</p> <p>Conclusion</p> <p>These data indicate that the discriminative ability of breast cancer classifiers is dependent upon genes that correlate with cell cycle progression.</p

Veterinary pharmaceuticals in the environment: an introduction

The production of swine, cattle, and poultry raised for human consumption represents a significant portion of the U.S. agricultural economy. To maximize production, livestock producers regularly use pharmaceuticals and hormones as supplements in animal feed and water to increase rates of weight gain, and prevent or treat diseases among their livestock. For example, in swine it is estimated that antibiotics are used for disease prevention and growth promotion in more than 90% of starter feeds, 75% of grower feeds, 50% of finishing feeds, and 20% of sow feeds. Equally relevant numbers are seen in beef cattle production (1-4). It has been well documented that measurable quantities of pharmaceuticals are excreted, often in original form, in feces and urine of livestock. Livestock waste, containing pharmaceuticals and hormones, is often used as fertilizer for farm fields or pastures and may result in nonpoint source pollution of ground or surface waters (5). Fiel