Friedmann Equations from Entropic Force

In this note by use of the holographic principle together with the equipartition law of energy and the Unruh temperature, we derive the Friedmann equations of a Friedmann-Robertson-Walker universe.Comment: latex, 8 pages, v2: minor modifications and to appear in PRD (Rapid Communication

Tgf-β1 produced by activated CD4+ T Cells Antagonizes T Cell Surveillance of Tumor Development

TGFβ1 is a regulatory cytokine with a crucial function in the control of T cell tolerance to tumors. Our recent study revealed that T cell-produced TGFβ1 is essential for inhibiting cytotoxic T cell responses to tumors. However, the exact TGFβ1-producing T cell subset required for tumor immune evasion remains unknown. Here we showed that deletion of TGFβ1 from CD8+ T cells or Foxp3+ regulatory T (Treg) cells did not protect mice against transplanted tumors. However, absence of TGFβ1 produced by activated CD4+ T cells and Treg cells inhibited tumor growth, and protected mice from spontaneous prostate cancer. These findings suggest that TGFβ1 produced by activated CD4+ T cells is a necessary requirement for tumor evasion from immunosurveillance

An Essential Role of the Forkhead-Box Transcription Factor Foxo1 in Control of T Cell Homeostasis and Tolerance

SummaryMembers of the Forkhead box O (Foxo) family of transcription factors are key regulators of cellular responses, but their function in the immune system remains incompletely understood. Here we showed that T cell-specific deletion of Foxo1 gene in mice led to spontaneous T cell activation, effector T cell differentiation, autoantibody production, and the induction of inflammatory bowel disease in a transfer model. In addition, Foxo1 was critical for the maintenance of naive T cells in the peripheral lymphoid organs. Transcriptome analyses of T cells identified Foxo1-regulated genes encoding, among others, cell-surface molecules, signaling proteins, and nuclear factors that control gene expression. Functional studies validated interleukin-7 receptor-α as a Foxo1 target gene essential for Foxo1 maintenance of naive T cells. These findings reveal crucial functions of Foxo1-dependent transcription in control of T cell homeostasis and tolerance

Tobacco smoking and sexual difficulties among Australian adults: a cross-sectional study

Background: Few studies have examined smoking and female sexual difficulties. The aim of this study was to investigate the association between current tobacco smoking and sexual difficulties in Australian men and women. Methods: Data for this study came from the Second Australian Study of Health and Relationships (2012–13), which includes a representative sample of 18 427 sexually active Australian adults (aged 16–69 years). The main study and outcome measures were tobacco smoking and sexual difficulties. A multiple logistic regression analysis was conducted to adjust for potential confounders. Results: Male heavy smokers (>20 cigarettes per day) were significantly more likely than non-smokers to have trouble keeping an erection [adjusted odds ratio (AOR) 4.14, 95% confidence interval (CI) 1.87 – 9.20; P < 0.0001], lack interest in having sex (AOR 2.18, 95% CI 1.20 – 3.97; P = 0.011), have anxiety about performance (AOR 2.46, 95% CI 1.24 – 4.86; P = 0.010) and be unable to come to orgasm (AOR = 2.81, 95% CI 1.23–6.42; P = 0.015). Female smokers were also significantly more likely than non-smokers to not find sex pleasurable (AOR 1.48, 95% CI 1.05 – 2.07; P = 0.025); and light female smokers were significantly more likely than non-smokers to be unable to come to orgasm (AOR = 1.44, 95% CI 1.05–1.98; P = 0.025). Conclusions: Current tobacco smoking was associated with sexual difficulties in both men and women. For women, even light smoking was associated with not finding sex pleasurable and being unable to come to orgasm

Modelling impacts of tidal stream turbines on surface waves

© 2018 Elsevier Ltd A high resolution Computational Flow Dynamics (CFD) numerical model is built based on a laboratory experiment in this research to study impacts of tidal turbines on surface wave dynamics. A reduction of ∼3% in wave height is observed under the influence of a standalone turbine located 0.4 m from the free surface. The artificial wave energy dissipation routine ‘OBSTACLE’ within FVCOM is shown to effectively capture the correct level of wave height reduction, reproducing the CFD results with significantly less computational effort. The turbine simulation system is then applied to a series of test cases to investigate impact of a standalone turbine on bed shear stress. Results suggest an apparent increase in bed stress (∼7%) upstream of the turbine due to the inclusion of surface waves. However, in the immediate wake of the turbine, bed stress is dominated by the presence of the turbine itself, accounting for a ∼50% increase, with waves having a seemingly negligible effect up to 9D (D is the turbine diameter) downstream of the turbine. Beyond this point, the effect of waves on bed shear stress become apparent again. The influence of OBSTACLE on bed stress is also noticeable in the far wake, showing a reduction of ∼2% in wave height

Modelling tidal stream turbines in a three-dimensional wave-current fully coupled oceanographic model

© 2017 The Author(s) A tidal turbine simulation system is developed based on a three-dimensional oceanographic numerical model. Both the current and turbulent controlling equations are modified to account for impact of tidal turbines on water velocity and turbulence generation and dissipation. High resolution mesh size at the turbine location is assigned in order to capture the details of hydrodynamics due to the turbine operation. The system is tested against comprehensive measurements in a water flume experiment and results of Computational Fluid Dynamics (CFD) simulations. The validation results suggest that the new modelling system is proven to be able to accurately simulate hydrodynamics with the presence of turbines. The developed turbine simulation system is then applied to a series of test cases in which a standalone turbine is deployed. Here, complete velocity profiles and mixing are realized that could not have been produced in a standard two-dimensional treatment. Of particular interest in these cases is an observed accelerated flow near the bed in the wake of the turbine, leading to enhanced bottom shear stress (∼2 N/m 2 corresponding to the critical stress of a range of fine gravel and finer sediment particles)

Autocrine/paracrine TGFβ1 is required for the development of epidermal Langerhans cells

Langerhans cells (LCs) are bone marrow (BM)–derived epidermal dendritic cells (DCs) that develop from precursors found in the dermis. Epidermal LCs are absent in transforming growth factor (TGF) β1-deficient mice. It is not clear whether TGFβ1 acts directly on LC precursors to promote maturation or whether it acts on accessory cells, which in turn affect LC precursors. In addition, the physiologic source of TGFβ1 is uncertain because BM chimera experiments showed that neither hematopoietic nor nonhematopoietic-derived TGFβ1 is required for LC development. To address these issues, we created mice transgenic for a bacterial artificial chromosome (BAC) containing the gene for human Langerin into which Cre recombinase had been inserted by homologous recombination (Langerin-Cre). These mice express Cre selectively in LCs, and they were bred to floxed TGFβRII and TGFβ1 mice, thereby generating mice with LCs that either cannot respond to or generate TGFβ1, respectively. Langerin-Cre TGFβRII mice had substantially reduced numbers of epidermal LCs, demonstrating that TGFβ1 acts directly on LCs in vivo. Interestingly, Langerin-Cre TGFβ1 mice also had very few LCs both in the steady state and after BM transplantation. Thus, TGFβ1 derived from LCs acts directly on LCs through an autocrine/paracrine loop, and it is required for LC development and/or survival

Optoelectronic properties and ultrafast carrier dynamics of copper iodide thin films

As a promising high mobility p-type wide bandgap semiconductor, copper iodide has received increasing attention in recent years. However, the defect physics/evolution are still controversial, and particularly the ultrafast carrier and exciton dynamics in copper iodide has rarely been investigated. Here, we study these fundamental properties for copper iodide thin films by a synergistic approach employing a combination of analytical techniques. Steady-state photoluminescence spectra reveal that the emission at ~420 nm arises from the recombination of electrons with neutral copper vacancies. The photogenerated carrier density dependent ultrafast physical processes are elucidated with using the femtosecond transient absorption spectroscopy. Both the effects of hot-phonon bottleneck and the Auger heating significantly slow down the cooling rate of hot-carriers in the case of high excitation density. The effect of defects on the carrier recombination and the two-photon induced ultrafast carrier dynamics are also investigated. These findings are crucial to the optoelectronic applications of copper iodide