bluuebunny/crossref_metadata_2025 huggingface dataset:
Audit committee structure and performance
Authors:   , McMullen Dorothy A.
Published: July 2024

In recent years the audit committee has become a major means for companies to monitor the reliability of the financial reporting process. This study provides empirical evidence concerning whether they accomplish this objective and what structural attributes enhance their ability to do so. To determine whether the presence of an audit committee affects the reliability of the financial reporting process, five potential financial reporting consequences of audit committees were developed involving the occurrence of errors, irregularities, and illegal acts. Five separate treatment samples were obtained and compared to randomly selected control groups. Approximate randomization tests were used to determine the association between the presence or absence of audit committees and the occurrence of the five financial reporting consequences. To test the attributes of audit committees that may enhance their ability to improve the reliability of the financial reporting process, a sample of companies with audit committees was partitioned from the treatment and control groups used in the original samples. Six structural attributes were selected for testing based on a theoretical development of the responsibilities and objectives of audit committees. Logistic regression was used to compare the audit committee attributes of companies with and without various types of unreliable financial reporting. Research results support the association between the presence of an audit committee and more reliable financial reporting. For all five financial reporting consequences, the audit committee variable was significant even in the presence of other company specific factors that could affect the quality of financial reporting. Logistic regression results indicate that a higher percentage of outside audit committee members with accounting and legal expertise is associated with higher quality financial reporting. For all five financial reporting consequences, companies with unreliable financial reporting had a lower percentage of CPAs and lawyers on their audit committees than the control companies. There also was evidence (for two of the five consequences) that a higher percentage of outside audit committee members and more frequent meetings are associated with more reliable financial reporting.
Ubiquitin plays a critical role in Hepatitis B virus envelope proteins MHC class I antigen presentation
Authors:   , Liu Yuanjie , Mehta Anand S.
Published: July 2024

Hepatitis B virus envelope glycoproteins Large (L), Middle (M) and Small (S) are targets of the host cellular immune system. The extent to which the host recognizes viral antigens presented by infected cells is believed to play a decisive role in determining if an infection will be resolved or become chronic. As with other antigens, HBV envelope polypeptides must be degraded, presumably by cellular proteasomes, to be presented by the MHC class I pathway. The M protein, which behaves like the S protein in protein folding and secretion, was used as a model to study this process and determine how ER quality control machinery monitors foreign polymeric proteins and disposes of them through the ER-associated degradation (ERAD) pathway. We found that unlike most ERAD substrates, which require ubiquitination for retrotranslocation and degradation, the HBV M protein, which only contains two lysine residues, can undergo rapid and complete, ubiquitin-independent, proteasome-dependent degradation. The utilization of this pathway has a functional consequence, since proteins degraded through it are poorly presented via MHC I. Interestingly, when the level of ubiquitination was increased through the insertion of additional lysine residues, the level of antigen presentation was significantly enhanced without altering the rate of protein degradation. This result indicates that the 11BV M and S proteins can utilize an ubiquitin-independent ERAD pathway to limit class I antigen presentation. In contrast, the HBV L protein, which includes the entire M and S domains and contains two additional lysine residues in its N-terminal preS1 domain, requires ubiquitination for its proteasomal degradation and subsequent antigen presentation. This result implies that during infection, the HBV L protein, but not the M or S proteins, is targeted for ubiquitin-dependent degradation and contributes to the class I antigen presentation of HBV envelope proteins. In conclusion, using HBV envelope proteins as a model, we have identified a novel ubiquitinin-dependent degradation pathway and determined that this pathway can have implications for antigen presentation and potentially viral pathogenesis.
Social problem-solving as a moderator of explanatory style and health
Authors:   , Trunzo Joseph J. , Nezu Arthur M.
Published: July 2024

There is a considerable amount of research supporting a relationship between explanatory style (ES) and health outcomes. While this relationship is significant, the correlations are moderate at best, suggesting the likelihood of additional variables of influence. One potential moderating variable is problem-solving ability (Peterson & Seligman, 1987). Social problem-solving (SPS) is a construct that has been shown to be important in various clinical and theoretical areas such as depression, obesity, and cancer (Nezu, Nezu & Perri, 1989; Nezu, Nezu, Houts, Faddis, & Friedman, 1998). It has also been shown to have a moderating effect on negative attributional style and depression (Nezu, Kalmar, Ronan, & Clavijo 1986). Given Peterson and Seligman's proposed relationship of problem-solving ability to ES and health and the finding of SPS as a moderator of negative attributional style and depression, it is worth investigating the relationships among SPS, ES, and health. It is hypothesized that SPS will serve as a moderating variable of ES and health. The potential benefits from this research could lead to programs aimed at improving problem-solving abilities and to gain a more positive ES, therefore potentially increasing general health and decreasing the incidence and duration of illness. Eighty-three subjects completed measures of attributional style, social problem-solving ability, depression, stress, mood, and cold/flu symptoms over an 8-week period. Analyses of these data do not support a relationship among SPS, ES, and health. The variables that accounted for the greatest amount of variance in cold/flu symptoms were stress and mood. Given the correlational nature of the study, conclusions from these data are limited, but indicate that further research investigating the impact of psychosocial variables to physical health is warranted.
A simulation study of a dynamic multiple machine, multiple job class job shop with priority dispatching considerations
Authors:   , Lowe Ralph West , Banerjee Avijit , Burton J
Published: July 2024

In many situations, certain "Job Shop" scenarios represent a complex queueing problem. A common constraint in many business and industry job shops is that certain jobs can only be processed on a specific machine, while the other jobs can be processed on more than one machine. Theoretically, it may be argued that a machine should be dedicated to each type or class of jobs. In the real world, many reasons may preclude this option. The job shop in this research is a real-world, finite-capacity system. The system is dynamic and stochastic in nature comprising of two independent machines with two classes of jobs arriving into a single queue. To provide a greater degree of control for schedulers, a new dispatching rule is developed in this study based on applying selectable weights to mean interarrival rates and mean processing times of job classes to establish decision rules for efficient dispatching of jobs to the two machines. A comprehensive simulation study is conducted to examine the effectiveness of the new rule. The results are compared to some selected, well-known job dispatching rules reported in the literature, in terms of various performance criteria. A full factorial, multivariate analysis of variance (MANOVA) is conducted to ascertain the significance of the main effects of the factors, as well as the significant interactions between factors, in terms of all the performance measures. Each significant factor is further investigated for differences in levels using Tukey's multiple comparison method, or HSD. The experimental results of this study show that the proposed dispatching rule, in conjunction with carefully chosen weighting parameters, tends to outperform all other dispatching rules (with respect to all the measures) in improving performance of the constrained job class under the different factor level combinations. The proposed rule, using different weighting parameters, also performed well under different factor level combinations for the non-constrained job class as well as for the overall system. The implications of the results yielded by the simulation experiments are discussed in detail. Finally, the managerial significance of the major findings are outlined and suggestions are made for further research in this area.
Behavior of waves in high density polyethylene geomembranes
Authors:   , Soong Te-Yang
Published: July 2024

In this dissertation, the behavior of waves of the type that are seen in field deployed high density polyethylene (HDPE) geomembranes was studied. The effect of four experimental variables on the behavior of the waves was evaluated. The variables were normal stress, original wave height, thickness of geomembrane and temperature. The resulting experimental design represented twenty-five separate tests each conducted for 1,000 hours. In addition, a single control test was maintained for 10,000 hours. Each of the tests utilized HDPE geomembranes with strain gages attached in a number of critical locations. The results of the strain measurements in the 1,000 hour tests were modeled and extrapolated to 10,000 hours using the Kelvin-Chain model. The applicability of the Kelvin-Chain model was justified on the basis of the results of the 10,000 hour test. The measured and extrapolated strains were then converted to stresses via the Maxwell-Weichert model and the stress relaxation master curves established using the results of the large scale stress relaxation experiments. With the completion of the experiments and their extrapolation into a near steady state condition, it was found that tensile strain up to 5% could be induced in the geomembranes, leaving residual stress equivalent to 22% of the yield stress remained in the geomembranes. It was also found that a contact between the geomembrane and the underlying subgrade soil is not likely to be achieved over time. The results of this dissertation show that if waves are to be avoided, the geomembrane must be essentially flat on the underlying subgrade before backfilling. Possible changes in the current practice of field deployment and seaming of geomembranes were provided.
Signal transduction and regulation of gene expression during replicative senescence of human fibroblasts
Authors:   , Tresini Maria , Cristofalo Vincent J
Published: July 2024

The focus of the work presented here was to gain insight on the mechanism underlying the inability of replicatively senescent fibroblasts to complete events of the G0/G1 phase of the cell cycle and to, ultimately, proliferate. In chemically-defined media activation of the IGF-I receptor (IGF-IR) is an absolute requirement for growth of early passage WI-38 fibroblasts. Recent evidence suggests that, in addition to the previously described signaling systems, IGF-IR controls cell growth through a novel signaling pathway activated at its C-terminus. We identified a novel gene (DBI-1) that is suppressed in response to activation of the IGF-IR C-terminus and used it as a marker to assess whether this pathway is functional in senescent cells. DBI-1 was expressed at similar levels by both young and senescent cultures of WI-38 cells, suggesting that the signaling pathway that leads to suppression of DBI-1 is intact in senescent cells. Another pathway crucial for transmission of mitogenic signals in response to activation of the IGF-IR as well as of other receptors-tyrosine kinases, is the Raf/MEK/ERK signaling cascade. We observed that stimuli that activate the ERK pathway, such as serum and the antioxidant NGA, fail to induce c-fos expression in senescent WI-38 cells. We also found that activation of ERKs is impaired in senescent cells and that in late passage cells there is an accumulation of unphosphorylated (inactive) ERK2 molecules. The senescenoe-associated decline in ERK activation is presumably caused by the decreased MEK activity since MEK phosphorylation is also lower in late passage cells. Additionally, we observed that both the phosphorylation and the DNA binding activity of the transcription factor p62TCF/Elk-1 is impaired in senescent cells. These results suggest that in senescent cells there are impairments in the activation of signaling molecules that are normally activated during the early G1 phase of the cell cycle. We also observed that senescent cells attain a G0 state distinct from that of young cells since late passage WI-38 cells lose the ability to express the quiescence-specific gene EPC-1. Downregulation of EPC-1 is also a characteristic of replicatively senescent cultures of dermal fibroblasts established from donors of various ages, even though there is no correlation between EPC-1 mRNA abundance and donor age. In summary, our data suggest that the G0/G1 phases are distinct between young and senescent cells. Furthermore, our data are in agreement with the hypothesis that failure of senescent cells to attain a normal G0 state and dysregulation of mitogenic pathways that should be activated in early G1, contributes to their inability to proliferate.
Processing, microstructure and property relationships in a powder metallurgy tool steel
Authors:   , Kumar K. Sharvan
Published: July 2024

A detailed microstructural examination has been made of T15 high speed tool steel processed from gas atomized powder and associated strength, toughness and hardness at elevated temperatures evaluated. Powders were screened into selected size fractions to include the rapid solidification regime, hot isostatically pressed and heat-treated. Some of the HIPed material was not-forged prior to heat-treatment. Two HIPing temperatures, two austenitizing temperatures and three tempering temperatures were included in the study. Atomized and consolidated materials were characterized using x-ray diffraction, optical and scanning electron microscopy. A segregated network structure is present in the atomized powder independent of the particle size, with MC and M(,2)C carbides present primarily at cell boundaries. The weight fraction and the overall carbide compsition are insensitive to particle size; the proportion of MC carbides increases with decreasing particle size. After HIPing, MC, M(,6)C and M(,23)C(,6) carbides are present in the form of individual particles in a ferritic matrix. Independent of prior particle size fraction, the carbide size distribution after HIPing is skewed to larger carbide sizes with increasing HIPing temperature, but with no significant change in volume fraction of carbides. At a given HIPing temperature the carbide size distribution for MC and M(,6)C carbides is dependent marginally on prior particle size fraction, being broader for the coarser size fractions. M(,23)C(,6) goes into solution during the austenitizing if the temperature is high enough and does not reprecipitate on tempering. Prior austenite grain size is influenced by the HIPing and austenitizing temperatures as well as the intermediate hot-forging step. MC and M(,6)C carbide size distributions in the fully heat-treated material, are influenced primarily by the HIPing temperature and to a lesser extent by the intermediate hot-forging step. Strength and toughness are enhanced by hot-forging. Property levels are similar to those of the corresponding commercial P/M tool steel. Hardness retention at elevated temperature is superior to that of the commercial material. The dependence of property levels on powder characteristics and processing parameters is understood in terms of the associated microstructures and densification mechanisms.
Conceptual design and selection of HVAC&R systems by combining knowledge based expert system with a building energy simulation program
Authors:   , Maor Itzhak , Reddy Agami T
Published: July 2024

The typical HVAC&R design process generates several alternative solutions (configurations of systems, subsystems and components), and then utilizes analysis and estimation tools to select a 'best' solution based on predefined selection criteria such as lowest Life Cycle Cost (LCC). This approach is limited by the engineer's experience, capabilities and time constraints, often resulting in missed opportunities for optimum system selection. Further, the latest equipment, design approaches, and concepts are not even considered. Knowledge-Based Expert System (KBES) can augment the current advanced building simulation tools by creating one entity that automatically generates, analyzes, and sorts design solutions subject to both site and user constraints. This dissertation describes the design and proof-of-concept demonstration for a computer-based HVAC&R conceptual design assistant. The research focuses on methodologies to synthesize and analyze HVAC&R systems by employing KBES and building energy simulation programs such as DOE-2. A commercial hybrid KBES shell has been selected and then programmed to include HVAC&R knowledge of components and systems, resulting in an ability to synthesize design alternatives using rule-based and frame-based knowledge representation mechanisms. The KBES shell also includes procedural programming capabilities that have the ability to perform simple heuristic cooling and heating design loads as well as first and maintenance cost calculations. Initiation, configuration and matching rules have been incorporated into the KBES to begin generation of design alternatives, configure the secondary and primary subsystems, and match applicable secondary systems to primary systems through site, configuration, and subsystems matching constraints. The ASHRAE/IESNA 90.1-1999 standard has been used to set the minimum allowed energy performance for equipment including fans, chillers, boilers etc., resulting in compliance with energy codes. In order to demonstrate the efficacy of this approach, a knowledge base applicable to large office buildings has been developed. The newly developed KBES has been applied to two cases: (i) to demonstrate the process of HVAC&R systems synthesis and evaluation and (ii) to demonstrate the sensitivity of every initiation parameter. This research clearly demonstrates the feasibility and methodology of developing intelligent tools to assist the HVAC&R practitioner in the early stage of the design.
The effect of phenytoin on transcription of key proteins of fatty acid metabolism in hyperkalemic periodic paralysis
Authors:   , Yudkowsky Michelle Lynne
Published: July 2024

Hyperkalemic penodic paralysis (HPP) is an autosomal dominant skeletal muscle disease characterized by any one of several sodium channel gene point mutations in the adult form of the [alpha] subunit (SkM1). The sodium channel defect is associated with a delayed inactivation of fast inward sodium current. It has been observed that co-expression of the Beta 1 ([beta]1) subunit with SkM1 is necessary for the normal kinetics of sodium channel inactivation and may be necessary for proper placement and function of SkM1 in the membrane. There is evidence that the primary defect in the sodium channel may cause a secondary alteration in triglyceride-associated fatty acid metabolism (TAFAM). The hypothesis to be tested was that TAFAM may influence the [beta]1/SkM1 interaction, contribute to the paralysis, and be involved in the action of the clinically efficacious drug phenytoin. It was the aim of this study to examine the effect of phenytoin treatment on the transcriptional regulation of the [beta]1 subunit and three key proteins in TAFAM: hormone sensitive lipase (HSL), carnitine palmitoyltransferase (CPT), and fatty acid binding protein (FABP). These transcripts were quantitated by competitive reverse transcription PCR in primary cultures of equine nondifferentiated and differentiated skeletal muscle from control (n = 3), heterozygote HPP (n = 3), and homozygote-affected HPP (n = 3) horses. Homozygote-affected cultures expressed significantly more [beta]1 transcript in differentiated cultures than either heterozygote or control cultures. Phenytoin decreased [beta]1 transcript in eight out of nine nondifferentiated cultures when genotypes were pooled and increased [beta]1 transcript in eight out of nine differentiated cultures. Homozygote-affected cultures expressed significantly less HSL transcript in both nondifferentiated and differentiated cultures than either heterozygote or control cultures. Phenytoin had no effect on HSL expression in nondifferentiated cultures and selectively increased HSL transcript in homozygote-affected differentiated cultures, abolishing the difference between genotypes. The level of CPT and FABP transcription was stable across genotype, differentiation, and phenytoin treatment. We conclude that these results suggest that the primary defect in HPP may secondarily increase [beta]1 and decrease HSL transcript levels and that the therapeutic action of phenytoin may involve regulation of [beta]1 and HSL transcription.
Electrochemical Reduction of Water Hardness for the Prevention of Fouling in Cooling Water Treatment
Authors:   , Wright Kamau , Cho Young I.
Published: July 2024

Scale deposition occurs along heat exchanger surfaces, resulting in a decrease in efficiency of heat transfer, a problem known as mineral fouling, which poses challenges in industrial applications. The prevalent form of scale is calcium carbonate (CaCO₃). The formation of this CaCO₃ scale on heat exchanger surfaces in industrial systems can be mitigated by reducing the concentration of calcium ions (Ca²⁺), bicarbonate ions (HCO₃⁻), or both, in the water utilized in the system. The common method of reducing this fouling ability is to reduce the concentration of calcium ions. In the present study, research and experiments were conducted for the purpose of reducing this concentration of calcium ions and the associated potential of CaCO₃ to cause precipitate fouling. To mitigate these effects, a direct current (DC) electric field was applied across electrodes placed in a stream of water, to electrochemically capture calcium ions and precipitate CaCO₃ before it could be deposited as scale along surfaces of a heat exchanger. The electrochemical system was applied at constant galvanostatic conditions of 0.4 A, and 0.3 A, in a stream of 5 gallons (19 liters) of hard water at a flow rate of 1 liter/minute. This system was also then applied in a fouling test setup at similar test conditions of 0.2 A, 0.5 A, and 1.5 A, and the fouling resistance was monitored over 48 hours to determine if the reduction of calcium ions indeed led to a decrease in mineral fouling in the system. The electrochemical system was successful at reducing hardness in water at an energy cost of 23kJ/Iiter per abatement of 100 ppm of hardness. The system was however not able to reduce fouling resistance during a fouling test. Electrochemical water softening is discussed and suggestions are proposed for how to modify the proposed system so that it can reduce fouling in addition to removing calcium ions.
Analysis and design of multiresolutional fuzzy variable structure controller
Authors:   , Nawathe Ratnakar Dhondiram
Published: July 2024

The dependence between accuracy and control complexity of control systems is discussed. Multiresolutional control systems are introduced as a tool of reducing control complexity. A multiresolutional feedback controller is introduced which uses different levels of granularity of the information to attain the prescribed accuracy. The results are presented to determine the number of levels and the number of granules in each of the levels of multiresolutional controller. An approach for engineering design of a fuzzy controller which uses multiresolutional representation is presented. The prescribed accuracy is different at different levels of granularity. When the prescribed accuracy is low, a fuzzy controller based on lower resolution information can be used. As the process moves from level to level, the prescribed accuracy becomes higher and approaches the highest accuracy, the resolution of information to fuzzy controller becomes high. The high accuracy of control means that the controlled variables will have to be represented at high resolution which increases the complexity of the controller which for a fuzzy controller is proportional to the number of rules to be evaluated and the granularity of its inputs. It was demonstrated how multiresolutional fuzzy controller can be merged with variable structure controllers (VSC) to develop a controller which guarantees the prescribed accuracy in the case of certain class of uncertain systems. The ability of fuzzy controller to handle measurement uncertainty can be used to make the VSC robust with respect to these uncertainties.
Relationship between community integration questionnaire (CIQ) scores and outcome in outpatient brain injury rehabilitation
Authors:   , Wingate Stephanie J. , Glascock Anthony Philip
Published: July 2024

The Community Integration Questionnaire (CIQ) has been developed for measurement of involvement in community activities, and has been used widely in brain injury rehabilitation settings. It is a self-report, multiple choice format questionnaire, with three subscales measuring home integration, social integration, and productive activity. The CIQ has been shown to discriminate between individuals with and without brain injury as well as among people with brain injury living in different situations. Standardized normative data is lacking, however, and sociodemographic concerns have been raised with regard to CIQ scores. Gender differences have been most consistent, with females performing higher than males on the subscale measuring home integration. The importance of obtaining retrospective pre-injury measures for relative comparison has been emphasized, due to the potential for individual differences even in the absence of a disability. No previous longitudinal studies have been published to compare CIQ change scores as a within-subject variable, in which each subject serves as his or her own control. The present study included 22 adults with acquired brain injury, referred for an outpatient brain injury rehabilitation evaluation. Pre-injury estimates of CIQ scores were calculated from available information regarding level of functioning just prior to the time of injury. The CIQ was administered to all subjects at the time of initial evaluation (pre-treatment) and again at the time of discharge from the program (post-treatment). All subjects received rehabilitation services through the Drucker Brain Injury Center/Community Re-Entry Program at MossRehab Hospital in Philadelphia, PA. Data were collected utilizing a retrospective chart review technique. Absolute and change scores were calculated for pre-injury, pre-treatment, and post-treatment periods. Analyses revealed significant decline in total CIQ score from pre-injury to pre-treatment, as well as significant improvement in total CIQ score from pre-treatment to post-treatment. Findings were significant for total and productive activity change scores according to whether the projected outcome had been achieved. Patterns of change were examined according to category of projected outcome. Sociodemographic, injury and rehabilitation variables were analyzed, with inconsistent results. The CIQ appears to be most sensitive to changes in productive activity after brain injury and subsequent rehabilitation with a vocational emphasis.
Regulation of Hepatitis B Virus replication by AKT and NF-[kappa]B signaling pathways in primary hepatocytes
Authors:   , Rawat Siddhartha , Bouchard Michael
Published: July 2024

Chronic infection with the hepatitis B virus (HBV) is a major risk factor for developing severe liver diseases such as hepatocellular carcinoma (HCC). Despite the availability of a vaccine, HBV-associated liver diseases remain a major worldwide health problem. HBx is a multifunctional protein encoded by the HBV genome; HBx stimulates HBV replication and is thought to play an important role in the development of HBV-associated HCC. HBx can activate the phosphatidylinositol 3 kinase (PI3K)/AKT signaling pathway in some cell lines; however, whether HBx regulates the PI3K/AKT signaling in normal hepatocytes has not been evaluated. In studies described here, we assessed HBx activation of PI3K/AKT signaling in an ex vivo model of cultured primary rat and human hepatocytes and determined how this HBx activity affected HBV replication. We report that HBx activates AKT in primary rat and human hepatocytes and that activation of AKT decreases HBV replication in these cells. HBx activation of AKT in primary hepatocytes decreased HBV mRNA and core protein levels, suggesting that AKT regulates HBV replication by affecting transcription of HBV mRNAs. In agreement with this, we show that the transcription factor hepatocyte nuclear factor (HNP) 4[alpha] is a target of HBx-regulated AKT, and we directly link HNF4[alpha] to HBx-regulated AKT modulation of HBV transcription and replication. Although 14Bx activates AKT to diminish HBV replication, we also show that an important effect of HBx activation of AKT is inhibition of apoptosis. HBx also activates the transcription factor NF-[kappa]B to inhibit apoptosis in cultured primary rat hepatocytes. The molecular mechanisms that underlie HBx activation of NF-[kappa]B in normal hepatocytes are undefined. We now report that HBx increases the levels of reactive oxygen species (ROS) in primary rat hepatocytes and that this elevation of ROS is responsible for HBx activation of NF-[kappa]B. Activation of NF-[kappa]B by HBx decreases HBV replication in primary rat hepatocytes. Consequently, our studies suggest that HBx activates cellular signaling pathways that simultaneously regulate HBV replication and cell survival. We propose that HBx functions as a rheostat that controls the level of HBV replication and the cellular environment to ensure non-cytopathic HBV replication.
Novel roles of Toll-Like Receptor-3 and microRNA-155 in HIV-1 infection of human macrophages
Authors:   , Swaminathan Gokul , Martin-Garcia Julio
Published: July 2024

HIV-1 infection of macrophages plays a key role in viral pathogenesis and progression to AIDS. Toll-like receptors (TLR) are innate immune receptors present in macrophages that detect various components of microbes and trigger host defenses. Mechanisms by which TLR activation modulates HIV-1 infectivity and the specific role of TLRs in sensing HIV-1 infection are not well characterized. By using primary monocyte-derived macrophages (MDMs) from healthy human donors, we found that activation of TLR3 and TLR4 abrogates HIV-1 infection through the upregulation of microRNA-155 (miR-155). In addition, ectopic miR-155 expression remarkably diminished HIV-1 infection in primary MDMs. TLR3 activation and ectopic miR-155 expression resulted in accumulation of HIV-1 late reverse transcription (RT) products and significant reduction in integrated pro-viruses. Furthermore, miR-155 downregulated several HIV-1 dependency factors involved in nuclear import of pre-integration complexes (ADAM10, Nup153, LEDGF/p75) and thereby inhibited HIV-1 at a pre-integration stage. Time-course experiments revealed that miR-155 expression was upregulated only until 24 hrs post TLR3 stimulation. This limited existence of miR-155 had a direct impact on HIV-1 inhibition, wherein the accumulated late RT products decreased as miR-155 levels waned. Interestingly, we observed that the anti-inflammatory cytokine, IL-10 was responsible for the stringent negative regulation of miR-155. TLR3 primarily senses dsRNA, a common viral replication intermediate that is absent during retroviral replication. Although viral particles of HIV-1 contain two copies of ssRNA genuine, each ssRNA contains multiple hairpin-like secondary structures that could potentially mimic a dsRNA entity. Therefore, we hypothesized that TLR3 could sense and respond to HIV-1 infection. By performing TLR3 inhibition studies in human macrophages as well as using bone marrow derived macrophages from TLR3-/- mice, we identified that TLR3 is required for production of HIV-1-induced IFN[beta], miR-155 and various inflammatory cytokines. Overall, our data suggests that TLR3 plays complementary roles in HIV-1 infection: pre-stimulation of TLR3 prior to HIV-1 infection induces miR-155 to impair viral nuclear import, and secondly, activation of TLR3 by HIV-1 controls viral replication through the generation of miR-155 and IFN[beta]. These studies highlight the therapeutic potential for manipulating TLR3 & miR-155 expression to control HIV-1 infection and replication.
The Effect of growth surface properties on the cultivation of anchorage-dependent animals cells and the development of novel surfaces for cell culture
Authors:   , Kent Bradley Lane
Published: July 2024

The physiological responses of anchorage dependent animal cells (3T6 mouse embryo fibroblast and A375 human malignant melanoma) to systematic variation of growth surface properties were determined for sulfonated polystyrene (PS-S), styrene-methacrylic acid copolymers (PS-MAA), and styrene-dimethylaminoethyl methacrylate copolymers (PS-DMAEMA). The optimal surface charge densities for attachment, spreading, and proliferation occur over narrow ranges and are not equal. On PS-S, the optimum charge densities for 3T6 are 2.5 charges/nm2 for attachment, 2.0 charges/nm2 for spreading, and 4.0 charges/nm2 for growth, while the maxima for A375 are at 2.0, 3.5, and 2.0 charges/nm2, respectively. On PS-MAA, the maxima for 3T6 are at 40-60 vol% MAA for attachment, 70 vol% MAA for spreading, and 50-60 vol% MAA for growth, while the maxima for A375 are at 20, 80, and >20 vol% MAA, respectively. On PS-DMAEMA, the maxima for 3T6 are at 70 vol% DMAEMA for both attachment and spreading, while the maxima for A375 are at 90-100 vol% DMAEMA for attachment and 60 vol% DMAEMA for spreading. The influence of inoculum density on cell attachment and growth was also studied. The initial cell density (cells/surface area) must be 103-104 cells/cm2 for 3T6 and 3 x 103 - 4 x 104 cells/cm2 for A375 to compare growth rates on different surfaces. To objectively compare cell attachment rates, the rate should be measured as cells/volume-time and the liquid phase cell concentration must be essentially constant. A fixed-surface bioreactor based on a reticulated vitreous carbon foam was used to cultivate 3T6, providing a high surface-to-volume ratio (17 cm2/cm3) and a low-shear (<0.1 dynes/cm2), chemically-inert. and potentially reusable environment. External medium circulation allowed aeration, nutrient monitoring, and medium replacement without disturbing the cells. Optimal flow rates for attachment (120 mL/h) and growth (>400 mL/h) were determined. Growth rates comparable to agitated microcarrier cultures were achieved.
Determinants of corporate tax avoidance strategy
Authors:   , Leauby Bruce Alan
Published: July 2024

The Economic Recovery Tax Act of 1981 liberalized the tax code allowing a significant number of U.S. firms to systematically avoid federal income taxes while other firms paid their fair share during the 1982-1985 time period. The objective of this study is to document the determinants of corporate tax avoidance behavior. This study developed hypotheses from the accounting choice literature to try to explain managerial decisions to avoid federal income tax. Seven firm specific variables were chosen either on the basis of their economic implications for tax avoidance behavior or because they proxy for the hypotheses developed in this study. The statistical results support the debt covenant, bonus plan, and political action committee hypotheses. Support is not provided for the political cost, ownership control, and capital intensity hypotheses. Based on these findings, the profile of a tax avoiding firm is a large firm, with a high debt to equity ratio, a bonus plan based on after-tax accounting earnings which gives a larger share of earnings to political action committees that are specifically established to contribute funds to members of the tax writing committees of Congress. The ownership percentage of voting stock held by directors and officers shows no relationship to tax avoidance behavior providing empirical evidence to support Fama's labor market efficiency theory. Finally, capital intensity does not explain tax avoidance. This result failed to support the theory behind the investment tax credit. Implications for changes in the national tax policy are provided in the thesis along with potential new accounting issues worth exploring.
Detection and resolution of multiple targets using time-frequency and deconvolution techniques
Authors:   , Xin Jianqiang , Bilgutay Nihat M.
Published: July 2024

In ultrasonic nondestructive testing (NDT) the backscattered echoes from the grain boundaries often mask the target signal, leading to difficulties in its detection and identification. The split spectrum processing (SSP) technique, which is based on the frequency diversity principle, has been used effectively to suppress grain noise when a single target is present. However, in general, more than one target may exist over the resolution cell, resulting in interference which can mask one or more of the targets and present difficulties in their detection and identification. It has been shown in this work that the inter-target interference between two targets exhibits strong variation with frequency. Therefore, by bandpass filtering the input signal at different center frequencies, it is possible to obtain an output signal which exhibits less interference between the adjacent targets compared to the original wideband signal. The simulation and experimental results show that by utilizing such bandpass signals, constant bandwidth and constant Q SSP algorithms can yield both signal-to-noise ratio enhancement (SNRE) and resolution improvement. Deconvolution techniques have been widely used to improve the resolution and quality of ultrasonic images. However, deconvolution techniques require a priori information about the system, which presents the main difficulty in their implementation. In this thesis, the Split Spectrum Processing (SSP) spectral histogram technique is utilized to estimate the system transfer function. The spectral histogram technique is based on the statistics of narrowband signals selected by the absolute-minimization operation. Theoretical analysis indicates that the spectral histogram is similar in nature to the Wiener filter transfer function and can therefore be used to estimate the optimal frequency region for L1 deconvolution. The theoretical and experimental results indicate that the proposed technique provides enhancement in identifying and extracting multiple targets. Finally, based on the SNR variation of the narrowband signals over the frequency range of SSP, an analysis is provided to determine the optimum rank for the order statistic filter with independent non-identically distributed inputs.
Multilevel voltage source inverters with phase shift SPWM and their applications in STATCOM and power line conditioner
Authors:   , Liang Yiqiao , Nwankpa Chikaodinaka Okechi Dike
Published: July 2024

Reactive power compensation and harmonic reduction are two relevant research problems that exist in modern electric power systems. With the advancement of modern power electronics technology in both circuits and devices, new and better solutions are being proposed and applied to solve these two problems. To compensate reactive power, a cascading voltage source inverter with a Phase-Shift, Unipolar SPWM switching scheme is proposed. The main circuit of this inverter is composed of several identical voltage source H-bridge inverters connected in cascade form. Advantages of this scheme include use of identically rated storage capacitors, similarly rated switches and diodes, quick system response to load changes, and easily achievable redundancy. To solve the harmonic reduction problem, the flying capacitor multilevel voltage source inverter is adopted to construct a novel power line conditioner. The Phase Shift SPWM switching scheme is also employed to operate the switches of this inverter. As a result, it is possible to extend the new power line conditioner to distribution systems or industrial applications where voltage usually ranges from 4.16kV to 13.8kV. It is shown that the proposed power line conditioner not only balances the unbalanced load, but simultaneously compensates the reactive power as well.
Mitogen-activated protein kinase and krotein kinase C-catalyzed caldesmon phosphorylation in vascular smooth muscle
Authors:   , Trappanese Danielle M. , Moreland Robert S.
Published: July 2024

Caldesmon is hypothesized to modulate contractile activity of smooth muscle by inhibiting actin-activated myosin ATPase activity, and inhibition is reversed by phosphorylation. Mitogen-activated protein (MAP) kinase is proposed to be the endogenous caldesmon kinase; however, MAP kinase-mediated phosphorylation can only account for Ser789 phosphorylation and not total caldesmon phosphorylation. We tested the hypothesis that MAP kinase and protein kinase C (PKC) are involved in stimulation-induced caldesmon phosphorylation and force development in swine carotid artery. We examined changes in resting and stimulated MAP kinase catalyzed Ser 789-caldesmon and total caldesmon phosphorylation levels in the presence of MAP kinase and/or PKC inhibitors. Our results demonstrated that caldesmon is regulated in the resting state and during agonist stimulation, albeit by different mechanisms. At rest, there is a basal level of activated p44 MAP kinase that phosphorylates caldesmon at Ser789. p42 MAP kinase phosphorylates caldesmon at a site(s) other than Ser789 and is regulated by a constitutively active PKC, potentially via modulation of MAP kinase phosphatase activity. In stimulated tissues, MAP kinase phosphorylates caldesmon at Ser789 and potentially other sites in response to histamine stimulation, whereas PKC-catalyzed caldesmon phosphorylation in response to phorbol 12,13-dibutyrate (PDBu) stimulation is at a site(s) other than Ser789. These data provide evidence that MAP kinase and PKC are endogenous caldesmon kinases but PKC may be more important in regulating MAP kinase-catalyzed caldesmon phosphorylation in resting as compared to stimulated tissues. Additionally, we examined the effect of MAP kinase and PKC-catalyzed caldesmon regulation on active force development using inhibitors of MAP kinase and/or PKC in siRNA caldesmon knockdown muscle strips. Our results show that caldesmon does not directly inhibit actin-activated myosin ATPase activity. Instead, caldesmon may regulate myosin ATPase activity and force development through a novel thin filament-associated inhibitory protein and inhibition is reversed by MAP kinase and PKC-mediated caldesmon phosphorylation. We have provided evidence that MAP kinase and PKC-mediated caldesmon phosphorylation has a critical role in regulating agonist-stimulated smooth muscle contraction and crossbridge cycling but may have a more significant role in regulating resting vessel tone and therefore resting blood pressure.
Nonlinear control of processes with actuator saturations
Authors:   , Valluri Sairam , Soroush Masoud
Published: July 2024

This dissertation concerns the fundamental problems of windup and process directionality in "input-output linearizing" control of multivariable nonlinear processes with actuator saturation nonlinearities. Two classes of general nonlinear but affine-in-control processes are considered: (a) delay-free processes with full state measurements, and (b) processes with incomplete state measurements and dead-times. The two fundamental problems are addressed by using a model predictive approach. The complete connections between input-output linearizing control and model predictive control are established: input-output linearizing control is simply shortest-prediction-horizon model predictive control. The model predictive control approach leads to nonlinear control laws that can be parameterized into two distinct parts: (i) an input-output linearizing controller that inherently includes an integral windup compensator and (ii) an optimal directionality compensator. The directionality compensator is a quadratic program that is trivially solvable online. In the case that the characteristic (decoupling) matrix of process is diagonal, the optimal directionality compensator is identical to "clipping". For general processes, however, neither direction preservation nor clipping can compensate for process directionality optimally. The concrete connections between the derived control laws, and modified internal model control and model state feedback, are established. When one of the derived control laws is applied to time-invariant linear processes, the resulting linear controller will exactly be a modified internal controller and in a special case, a model state feedback controller. The application and superior performance of the derived control laws and the optimal directionality compensator are demonstrated by numerical simulations of chemical and biochemical processes with input saturation nonlinearities.
Predictors of body image dissatisfaction in obese women seeking weight loss treatment
Authors:   , Kopyt Diana Monica , Lowe Michael R
Published: July 2024

Obese females, shown to experience more body dissatisfaction than obese males and normal weight individuals, frequently present for weight loss treatment hoping that weight reduction will improve their body image. However, weight loss alone may be an imperfect solution to body image problems. It has been recommended that body image therapy be incorporated with weight loss therapy to address this issue. An increased understanding of body image in obese women presenting for weight loss treatment may facilitate development of such therapies. Therefore, this investigation assessed the ability of several recognized risk factors (obesity onset, teasing history, and sociocultural influence) in conjunction with a cognitive style factor, previously unexamined in relation to body image, to predict body dissatisfaction in 74 obese, female, weight loss treatment seekers. A hierarchical multiple regression analysis indicated that 30% of the variance in body dissatisfaction was accounted for by this model; after controlling for current age, cognitive style was the only predictor which significantly added to change in R2. Repeating this analysis using depressive symptomatology as an additional covariate, 41% of the variance in body dissatisfaction was explained; again cognitive style was the only variable which significantly added to change in R2 after covariate effects were removed. To evaluate the severity of body dissatisfaction and related variables in this obese sample, a comparison group of 62 normal weight, female, university students was included. Although no significant group differences in depressive symptomatology or cognitive style were found, obese participants reported significantly more body dissatisfaction and weight/size teasing. Secondarily, this study attempted to clarify whether obesity onset during certain developmental periods differentially influences the development of body dissatisfaction. A one-way ANOVA indicated no significant differences in body image between obese participants who first became overweight as children, adolescents, or adults. Finally, an exploratory principal components analysis examined whether measures of body dissatisfaction and measures of the extent to which overall self-evaluation is affected by body dissatisfaction would load on a single factor or emerge as separate factors. Separation of these measures was not empirically supported. Implications for treatment and future research are discussed.