10,002 research outputs found

    Electronic properties of the pseudogap system (TaSe4)2I

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    The room temperature ``metallic'' properties of the quasi-one-dimensional charge density wave system (TaSe4)2I differ markedly from those expected of either a Fermi or a Luttinger Liquid. We discuss evidence for the simplest possible explanation of the observed behavior of (TaSe4)2I in its conducting phase - namely the existence of large quasi-static fluctuations of structural order, which however remain of finite extent above the charge density wave transition temperature. These fluctuations produce a pseudogap in the density of states. We compute the temperature dependence of the optical and DC conductivities of (TaSe4)2I in its conducting phase, the nature of its core hole spectra, and the NMR relaxation rate. Predictions for these quantities are made on the basis of a Lee, Rice and Anderson model. This model represents the simplest theory of a pseudogap, and gives satisfactory agreement with experiment in the cases where comparisons can be made. In contrast, the predictions of a strongly correlated (Luttinger Liquid) model appear to to contradict the data. The chief remaining discrepancy is that the gap appearing in transport quantities is less than that observed in photoemission. We discuss some possibilities for resolving this issue.Comment: 41 pages latex, 11 ps figures, uses IOP macro

    Senior Recital: Shannon Lee Pennell, soprano

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    Yoga and the Effects on Balance, Hamstring Flexibility, and Blood Pressure

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    Yoga is an ancient form of exercise and meditation that has recently gained popularity in the United States. Medical research regarding the benefits of yoga, however, continues to be in demand. The purpose of this study was to determine the effects of yoga on normal healthy individuals. The focus of this study revolved around balance, hamstring flexibility, and blood pressure changes after six weeks of yoga training. Eighteen normal healthy individuals between 20-33 years of age participated in this study. Subjects were assessed using the NeuroCom®Balance Master test for rhythmic weight shift (RWS), the Functional Reach Test (FRT), the measure of blood pressure (BP), the Sit-and-Reach Test (SRT), and the Single Limb Stance Timed Test (SLST). The yoga group performed a random combination of 14 asanas and one pranayama in a six-week yoga-training program that met for 45 minutes, three times per week. The walking group (control group) walked below their target heart rates and performed basic hamstring stretching three times per week for six weeks. Paired samples t-tests indicated significance for diastolic blood pressure (Sig .. 04) and on-axis velocity RWS anterior-posterior (Sig .. 048) for the yoga group and for SLST on the left with eyes closed (Sig .. 005) for the walking group. Wilcoxen tests indicated significance for the yoga group in the SRT (Sig .. 003) and SLST on the right with eyes open (Sig .. 003) and eyes closed (Sig .. 021). These findings provide evidence that the practice of yoga is beneficial in improving physical well-being

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    Characterizing Vaginal Gene Expression in Prepubertal Gilts

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    The best-known predictor of reproductive success in gilts is the age at puberty. Early puberty (i.e., d170 – d180 of age) is associated with improved long-term reproductive performance and more full value offspring for market. The ability to predict, in the prepubertal stage, the age that a replacement gilt would be expected to achieve puberty has great reproductive and economic advantages. This work focuses on identifying biological markers that are potentially predictive of age at puberty. Study 1 identified changes in the vaginal epithelium during gilt reproductive development. Pre-pubertal gilts (n =13) were followed from d70 of age until first estrus or d213-215 of age. Blood, vaginal epithelia, and anogenital distance were collected at five timepoints during reproductive development [d70/77 (on-farm arrival), d100/110 (mid-folliculogenesis), d130 (post-folliculogenesis), d160 (start of boar exposure) and first estrus or end of trial (d214 of age)]. Total RNA was isolated from vaginal epithelia and relative gene expression of two toll-like receptors (TLR-4 and TLR-5), tacykinin precursor-3 (TAC-3), insulin-like growth factor-1 (IGF-1), and estrogen receptor-alpha (ER-α) was quantified by real time q-PCR, relative to expression of ribosomal protein lateral stalk subunit P0 (RPLP0). Expression of IGF-1 and TAC-3 were up-regulated 9- and 7-fold, respectively at d160 (P \u3c 0.05). Expression of ERα tended to be upregulated 3-fold at d100 (P = 0.08) and expression of TLR-4 and TLR-5 was lowly detected prior to first estrus. Anogenital distance was positively correlated to age at first estrus and negatively correlated to daily gain (P \u3c 0.01; r = 0.83). In experiment 2, pre-pubertal gilts (n = 29) were followed from d70 of age until first estrus or d215 of age. Vaginal swabs were collected at similar timepoints as described in experiment 1. By d215 of age, 19 females were classified as expressing estrus ‘early’ (d160 to d181), 4 were ‘average’ (d181- d202), and 6 were ‘late’ or ‘anestrus’ (d202 to d215). A subset of 5 gilts that expressed estrus early and 5 gilts that expressed estrus ‘late’ or ‘anestrus’ were used for vaginal transcriptome analysis using RNAseq and vaginal samples at d100, d130, and d160 of age. Data normalization used the reads per kilobase million (RPKM) method. Fold change differences were calculated across genes, within each estrus grouping (early or late). Differences in gene expression between ‘early’ and ‘late’ gilts were calculated using a Welch two-sample t-test in R (v 4.0.2). A gene selection process was used based on differential expression at each time point, between estrus groups, and across multiple time points to identify target biomarker genes. The process reduced total differentially expressed genes from \u3e 2,000 to 6 genes of interest, with genes Lin28 homolog A (LIN28A), Anoctamin 2 (ANO2), and Lysl oxidase homolog 2 (LOXL2) more highly expressed in early estrus females. Genes of interest relative to late estrus females were Glycogen synthase 2 (GYS-2), Growth regulating estrogen receptor binding 1 (GREB-1), and Interferon alpha 16 (IFN-Alpha-16). Gene LIN28A had higher expression in early estrus gilts (P \u3c 0.05). There was no significance between early and late estrus gilts for gene ANO2 but was expressed at least 10-fold greater in early estrus gilts at d130 of age. Gene LOXL2 tended to be expressed at higher levels in early estrus gilts across all time points than their late estrus counterparts (P =0.06). For the late estrus gilts, GYS-2 was 35 and 15-fold greater at both d100 and d130 of age (P = 0.04). Gene GREB-1 was expressed more than 10-fold greater in late estrus gilts, with a tendency at d160 of age (P = 0.09). Lastly, IFN-Alpha-16 tended to be more expressed at d100 of age (P = 0.06) in late females. Overall, there are distinct differences in vaginal gene expression at a given day of age for replacement gilts that may be used to predict age at puberty. Within this dataset, 100, 130, and 160 days of age may be ideal timepoints for identification of early estrus in pre-pubertal gilts; however, a more robust dataset analysis is necessary to pinpoint the ideal day of age in reproductive development to serve as a marker for identification of early estrus. The goal of the third chapter of this dissertation was to collect descriptive data of gilt rearing practices in the Midwest. A successful gilt development program is critical to the success of a production system because it has a direct effect on reproductive performance. While there have been reviews of literature for current industry practices employed for reproductive management (Kraeling and Webel, 2015), and performance data collected and reported by Metafarms, there is little to no data that includes both gilt management practices and decisions throughout reproductive development and a sow’s first parity within a breeding herd. Therefore, the objective of this survey was to obtain an understanding of gilt development practices across the Midwest to ensure that the next phases of research have high practical application and relevance. A total of 10 respondents participated, with farms located in Nebraska, South Dakota, Iowa, and Minnesota. These farms collectively manage approximately 43,000 sows. Data was collected and analyzed for descriptive statistics within Microsoft Excel. The herd parity 3 after gilt acclimation, with a minimum parity of 2.1 and the highest parity average of a 5. With such a young herd parity average range, it means animal removal is occurring at a young production age and warrants further investigation into reasons for removal. Based on this survey, more detailed information on gilt rearing, diet composition, and space per pig needs to be obtained. In conclusion, vaginal gene expression appears to change in concert with circulating reproductive hormones, with significant changes in IGF-1 and TAC-3 occurring at the start of boar exposure (d160 of age). Anogenital distance was positively correlated to age at first estrus and negatively correlated to daily gain, but due to inconsistencies in measurement collection, caused by events like gilt restlessness and vulva clenching makes this unapplicable for on-farm application. There are distinct differences in vaginal transcriptome between gilts deemed ‘early’ and ‘late’ estrus. Within this dataset, there were three genes of interest that have greater expression in ‘early’ gilts, and three genes of interest that have greater expression in ‘late’ estrus gilts. Currently, d100, d130 and d160 may be ideal timepoints for identification of early estrus in pre-pubertal gilts, but a larger sample size is necessary to pinpoint the ideal deal in reproductive development. Identification of the ideal age for pubertal detection, paired with an understanding of common gilt rearing practices and diet regimes can provide swine producers with information to maximize their gilt development program and reduce the number of replacement females needed within a herd each year

    Junior Recital: Shannon Pennell, soprano

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    Size and Shape of Multi-Walled Carbon Nanotubules Influences Exposure-Induced Airway Inflammation and Tissue Fibrosis in a Mouse Model

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    Purpose: Multi-walled carbon nanotubes (MWCNTs) are nano-scale fibrous particles that are increasing in use for a variety of common consumer products. These materials have unique properties that offer major technological benefits, but can also pose an immense public health risk; especially in occupational settings. As new materials, the toxicological impacts of MWCNTs are still widely unknown, however, the nature of these materials has been identified as similar to asbestos in terms of respiratory harm potential. After particle-induced lung injury, a series of pro-inflammatory and fibrotic events occur in an attempt to heal damaged tissue, however, this exposure can lead to unrestrained fibrosis and development of lung disease. Excessive collagen accumulation around airways and interstitial tissue can be quantified to better understand these disease processes. The goal of this project was to identify how a single respiratory exposure to MWCNT of different sizes and shapes can affect the progression of lung disease (fibrosis) over time, at two different post-exposure intervals. Methods: Adult C57BL/6 mice in even sex ratio were exposed with oropharyngeal instillation to one dose (50 micrograms) of MWCNT of different lengths and diameter (“Wide Short”, WS, “Narrow Short”, NS, and “Narrow Long”, NL) suspended in dispersion media. Control mice were exposed only to dispersion media (DM). Lung tissue was collected from two different post- exposures: 7 days and 56 days. Laser scanning cytometry (iCys) was used to image Trichrome stained lung tissue and quantify airway thickness and interstitial collagen accumulation. Results: Distinct differences in airway thickness and interstitial collagen accumulation were observed at both 7 and 56 day post-exposure intervals among MWCNT exposed groups and control. Conclusion: The differences in collagen burden at both post-exposure intervals suggests that MWCNT size and shape influence progression of airway and interstitial collagen accumulation that could lead to development of MWCNT-induced lung disease

    Polyanhydride nanovaccine platform against bacterial pathogens

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    This thesis focuses on the design of novel strategies for the prevention and treatment of bacterial infections using polyanhydride nanoparticles as a vaccine delivery platform. The overall goal of this research is to design efficacious vaccines against the respiratory bacterial pathogens Streptococcus pneumoniae and Yersinia pestis using polyanhydride nanoparticles to elicit a protective immune response to the pneumococcal surface protein, PspA, and the Yersinia fusion protein, F1-V, respectively. Polymers and copolymers based on the various anhydride chemistries (i.e., CPTEG, CPH, and SA) were investigated as nanovaccine formulations for antigen delivery. The mechanism of action of polyanhydride nanoparticles as vaccine adjuvants was investigated to better understand how these nanovaccines interact with immune cells at early time points (48 hours) and through the evaluation of the immune response at extended time points (~several months). Fluorescently-labeled antigen was delivered in 50:50 CPTEG:CPH nanoparticles and compared to soluble protein and protein adjuvanted with MPLA initially. Polyanhydride nanoparticle-encapsulated protein demonstrated enhanced persistence, cellular uptake and immune cell interactions at early time points compared to soluble protein, or MPLA-adjuvated protein. To investigate how prolonged antigen presence affected vaccine efficacy, several polyanhydride chemistries were tested and compared to MPLA at 14, 36, and 63 days after administration. The 50:50 CPTEG:CPH nanovaccine formulation elicited a robust humoral immune response, which significantly increased in titer and avidity at each of the time points investigated, suggesting the presence of long-lived plasma cells as a result of immunization with this polyanhydride nanovaccine. Once a better understanding of the mechanism of action of polyanhydride nanoparticles was obtained, these findings were used to design efficacious nanovaccines against two respiratory pathogens, S. pneumoniae and Y. pestis. The encapsulation and release of PspA from polyanhydride nanoparticles was examined and it was demonstrated that PspA retaining its stability, antigenicity, and biological functionality upon release from both 50:50 CPTEG:CPH and 20:80 CPH:SA nanoparticles. Based on these results, the in vivo immune response to vaccination with PspA nanovaccine formulations was evaluated and a protective vaccine against lethal challenge with S. pneumoniae based on polyanhydride nanoparticles was designed. Additionally, the in vivo immune response to vaccination with F1-V nanovaccine formulations was examined to design a protective vaccine against lethal challenge with Y. pestis including novel small molecule adjuvants in nanovaccine formulations with the goal of inducing protective immunity against Y. pestis challenge at both early time points (~several weeks) as well as after extended periods of time (~several months). Overall, the work described in this thesis lays a platform for the use of polyanhydride nanoparticles for a combination vaccine against both influenza and pneumonia as well as for the delivery of antimicrobial drugs
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