1,706 research outputs found

    Effective squirmer models for self-phoretic chemically active spherical colloids

    Full text link
    Various aspects of self-motility of chemically active colloids in Newtonian fluids can be captured by simple models for their chemical activity plus a phoretic slip hydrodynamic boundary condition on their surface. For particles of simple shapes (e.g., spheres) -- as employed in many experimental studies -- which move at very low Reynolds numbers in an unbounded fluid, such models of chemically active particles effectively map onto the well studied so-called hydrodynamic squirmers [S. Michelin and E. Lauga, J. Fluid Mech. \textbf{747}, 572 (2014)]. Accordingly, intuitively appealing analogies of "pusher/puller/neutral" squirmers arise naturally. Within the framework of self-diffusiophoresis we illustrate the above mentioned mapping and the corresponding flows in an unbounded fluid for a number of choices of the activity function (i.e., the spatial distribution and the type of chemical reactions across the surface of the particle). We use the central collision of two active particles as a simple, paradigmatic case for demonstrating that in the presence of other particles or boundaries the behavior of chemically active colloids may be \textit{qualitatively} different, even in the far field, from the one exhibited by the corresponding "effective squirmer", obtained from the mapping in an unbounded fluid. This emphasizes that understanding the collective behavior and the dynamics under geometrical confinement of chemically active particles necessarily requires to explicitly account for the dependence of the hydrodynamic interactions on the distribution of chemical species resulting from the activity of the particles.Comment: 26 pages, 11 figure

    Bank Failure prediction: corporate governance and financial indicators

    Get PDF
    Most failure prediction studies have relied on using financial ratios as predictors. The most suitable financial predictors for banks are financial ratios following the CAMEL rating system. Also, corporate governance has been proven to be an important aspect of banks, especially after the financial crisis. Given its importance, we test the ability of corporate governance to enhance the prediction of bank failure. While there are only few studies that examine efficiency of corporate governance as a failure predictor, there are scarcely any studies that examine it as predictor of US banks failure. Using discriminant analysis, we predict the failure of banks insured by the Federal Deposit Insurance Corporation during the period from 2010 to 2018 using financial and non-financial predictors. We find that combining CAMEL ratios with corporate governance variables not only enhances the accuracy of prediction but also extends the time horizon of prediction to three years before failure. We also show that the earnings of banks are more significant in predicting bank failure than the capital structure and asset quality. The results further reveal that the CEO compensation, voting rights and institutional ownership are more significant predictors than the board characteristics. These results are robust when using logit regression. This paper provides insight to banks, regulators and shareholders by showing that corporate governance and banks earnings are strong predictors of bank failure

    Neuro-Immuno-Endocrine Interactions in Early Life Stress and Heroin Withdrawal Timeline

    Get PDF
    Both heroin abuse and early life stress (ELS) affect the immune system and the hypothalamic-pituitary-adrenal (HPA) axis. Additionally, accelerated aging due to mild inflammation has been indicated in these conditions. The present study aims to compare plasma levels of apoptosis markers, inflammatory markers, and stress hormones during early heroin abstinence period. Thirty-one individuals with heroin/opioid use disorder who had heroin-ELS and 26 of their siblings who were not abusing substances (ELS), and 32 individuals with heroin/opioid use disorder without a history of ELS (heroin-no ELS) were included in the study. The levels of interleukin-6, C-reactive protein, erythrocyte sedimentation rate, albumin, alanine transaminase, aspartate transaminase, and white blood cell count were assessed as the inflammatory and biochemistry markers. Also, apoptosis markers including tumor necrosis factor (TNF)-related weak inducer of apoptosis, TNF-related apoptosis-inducing ligand, soluble tumor necrosis factor receptor type I as apoptosis markers were detected by enzyme-linked immunosorbent assay. ELS was simultaneously evaluated using the Childhood Trauma Questionnaire, Minnesota Multiphasic Personality Inventory, and beck depression inventory scales. Besides, heroin craving was assessed by Daily Drinking/Drug Questionnaire score in individuals with heroin use disorder. This is the first study to evaluate the inflammatory, stress, and apoptosis markers during heroin abstinence, supporting the association between ELS and peripheral pro-inflammatory markers' levels and HPA axis. © 2019 S. Karger AG, Basel

    Therapeutic potential of quercetin on human breast cancer in different dimensions

    Get PDF
    Background: There has been an extensive range of incidence and mortality of breast cancer (BC), and the comprehensively available treatments for BC have not been completely successful in achieving satisfactory outcomes up to date. Hypothesis: Recently, we are watching intense attention paid to the utilization of natural compounds as a novel therapeutic strategy for cancer treatment. Quercetin, a dietary flavonol in a large group of commonly consumed foods, is widely illustrated to apply inhibitory effects on cancer progression through several mechanisms including apoptosis enhancement, cell cycle arrest, metastasis and angiogenesis inhibition, antioxidant replication and estrogen receptor modulation. Methods: We reviewed the most relevant papers published from 2009 to 2018 (except 15 articles), using �pub med� and �web of science� and the search terms �Quercetin�; �Breast cancer�; �Flavonoid�; �Apoptosis�; �Cell cycle�; �chemotherapy�; �Drug resistance�; �Metastasis; �Oxidative stress�, �Breast cancer receptors� and �Quercetin derivatives�. We selected studies on the association of quercetin with breast cancer in different dimensions. Results: Despite the remarkable number of studies on quercetin�s efficacy, multiple aspects of this herbal compound have not been clarified well and this review provides a summarized update of the recent evidence on biologically available efficacies of quercetin which would establish a further biological basis for the potential therapeutic acquisition of quercetin as an anticancer drug. Conclusion: Basic, epidemiological and genetic studies point to the potential role of quercetin in the treatment of breast cancer, but randomized and controlled trials are of great importance to establish the clinical efficacy of quercetin in ill or at-risk subjects. © 2019, Springer Nature Switzerland AG

    Revisiting Corporate Governance and Financial Risk-Taking

    Get PDF
    Corporate governance attributes have varying effects on risk taking when variables are examined separately. We study the effects of a large range of corporate governance attributes on risk taking using a comprehensive US sample. Our findings confirm that although there are certain characteristics that drive this positive effect such as compensation structure, there are those which have the opposite effect such as board-level attributes. Our paper contributes to the broader literature on the relationship between corporate governance and risk in financial institutions, which are often overlooked in traditional studies. We shed light on the importance of studying corporate governance at a granular level rather than using a single index. The findings offer insights to regulators in determining suitable corporate governance frameworks to ensure the protection of investors rights in financial institutions

    The Effects of Silymarin and Cyclosporine A on the Proliferation and Cytokine Production of Regulatory T Cells

    Get PDF
    Background: Immunosuppressive agents are necessary to enhance allograft tolerance after transplantation and the treatment of autoimmune disorders. Regulatory T cells (Tregs) play a pivotal role in improving allograft tolerance and determining the fate of transplanted organs. Therefore, the aim of this study was to investigate the immunomodulatory effects of cyclosporine A (CsA) and silymarin on the proliferation and cytokine production of Tregs. Methods: Peripheral blood mononuclear cells (PBMCs) were obtained from healthy voluntaries and Tregs were isolated using an immunomagnetic separation method. The phenotypic characteristics of Tregs were determined by flow cytometry. Tregs were expanded and then cultured with different concentrations of CsA and silymarin. The effects of CsA and silymarin on the viability, proliferation, and transforming growth factor-beta 1 (TGF-β1) production of Tregs were determined after 3 and 5 days of culture. Results: CsA significantly decreased Treg proliferation in a dose-dependent manner (p < 0.01�0.05). CsA failed to change TGF-β1 production of Tregs. On the contrary, silymarin significantly increased the proliferation of Tregs (p < 0.01�0.05). A statistically significant increase was also observed in the TGF-β1 production of Tregs (p < 0.01�0.05). Our data showed that Treg viability was not compromised by CsA and silymarin. Conclusion: Overall, the results of this study for the first time indicate that silymarin, unlike CsA, has the ability to increase the proliferation and TGF-β1 production of Tregs and may be beneficial in the treatment of autoimmune disorders and improvement of Treg-dependent allograft tolerance after transplantation. © 2019, © 2019 Taylor & Francis

    The combination of retinoic acid and estrogen can increase germ cells genes expression in mouse embryonic stem cells derived primordial germ cells

    Get PDF
    A B S T R A C T Generation of germ cells from embryonic stem cells in vitro could have great application for treating infertility. The temporal expression profile of several genes was expressed at different stages of germ cell development and examined in differentiation the mouse embryonic stem cells. Cells were treated in three groups of control, with 10−8M of all-trans retinoic acid and the combination of 10−9M of 17β-Estradiol and retinoic acid for 7, 12, 17 or 22 days. Quantitative RT-PCR and Immunofluorescent were used to investigate the possible inductive effects of estrogen on mouse embryonic stem cell-derived primordial germ cells. mRNA expression of Oct4 and Dazl were downregulated in embryonic stem cells by the retinoic acid group, whereas Mvh transcription was reduced by retinoic acid and estrogen group in these cells compared to the control group. But, retinoic acid with estrogen group-treated cells exhibited increased mRNA expression of Stra8, Fragilis, Sycp3, GDF9, and Stella compared to untreated controls. The expression of Stella and Mvh proteins were remarkably increased in cell colonies. This study shows that estrogen affects the expression of specific markers of primordial germ cells. Also, estrogen and retinoic acid speed up and increase the level of expression of specific markers. Keywords: Gene expression profiling Immunofluorescent Mouse embryonic stem cells Primordial germ cells RT PC

    Concepts and Dimensions in Continuous Midwifery Care Models Based on the Experiences and Expectations of Stakeholders: A Meta-Synthesis

    Get PDF
    Context: Pregnant women’s have access to different models of care especially to those who provide continuous care and this is one of the recommendations of the world health organization (WHO) for promoting maternal health. Moreover, to provide adequate services in care models, the experiences and perceptions of mothers, providers of prenatal care, and other stakeholders should be taken into consideration. Objectives: A systematic meta-synthesis was carried out to inquire into the findings of some qualitative studies aimed to explore the concept and dimensions of continuous midwifery care including experiences, perspectives and perceptions of engaged people. Data Sources: This study was the first step of an action research designed to develop a midwifery model of care. Qualitative research articles published between 2005 and 2015 on experiences, attitudes, expectations and opinions of stakeholders in models of midwifery care were collected from Google scholar, Elsevier, and PubMed databases. Study Selection: Following the various stages of the scrutiny of the abstracts and contents of the collected articles, five faculty members finally selected 21 qualitative research articles as eligible for inclusion in the meta-synthesis. Results: The findings of meta-synthesis showed that continuous midwifery care for pregnantwomenas a highly important process revolves around at least five basic themes: continuity of care, compliance with needs satisfaction levels, regulation of care environment, and the philosophy of providing continuous care. Conclusions: Given the importance of access to healthcare as a right for pregnant women and given the key role of continuous midwifery care in health promotion and maternal satisfaction, it is suggested based on the results of the study that rigorous local and national research in this area to be carried out so that adequate models of continuous midwifery care can be designed and implemented based on the findings

    Comparison of the Percentage of Regulatory T cells and their p-STAT5 Expression in Allergic and Non-Allergic Common Variable Immunodeficiency Patients

    Get PDF
    Background: Common Variable Immunodeficiency (CVID) is a primary immunodeficiency characterized by an immunologic deficiency in immunoglobulin production. Regulatory T cells (Tregs) play a key role in preventing the development allergic disorders. p-STAT5 is a known factor for the function and survival of Tregs. This study aimed to investigate the number of Tregs and their p-STAT5 expression in allergic and non-allergic CVID patients. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from 10 healthy volunteers, 10 allergic patients, and 16 CVID patients (allergic and non-allergic) using Ficoll density centrifugation. The percentage of Tregs in PBMCs was analyzed by flow cytometry. Tregs were also isolated from participants using an immunomagnetic separation method and p-STAT5 expression was evaluated in Tregs using flow cytometry. Results: The results revealed that Treg percentage was significantly lower in the CVID patients than the control groups (healthy and allergic individuals) (p<0.001). There was a significant reduction in Treg percentage in allergic patients compared to healthy subjects (p<0.05). No significant difference in Treg percentage between allergic and non-allergic CVID patients was observed. The expression of p-STAT5 in Tregs was significantly lower in CVID patients than the control groups (p<0.001). In addition, the expression of p-STAT5 in Tregs of allergic patients was significantly decreased compared to healthy subjects (p<0.001). However, the deference of p-STAT5 level was not statistically significant between allergic and non-allergic CVID patients. Conclusion: These findings suggest that p-STAT5 signaling defect and decreased Treg number may not participate in the development of allergy in CVID patients. © 2018, © 2018 Taylor & Francis
    corecore