Transforming growth factor beta (TGF beta) mediates schwann cell death in vitro and in vivo: Examination of c-jun activation, interactions with survival signals, and the relationship of TGF beta-mediated death to schwann cell differentiation

In some situations, cell death in the nervous system is controlled by an interplay between survival factors and negative survival signals that actively induce apoptosis. The present work indicates that the survival of Schwann cells is regulated by such a dual mechanism involving the negative survival signal transforming growth factor beta (TGF beta), a family of growth factors that is present in the Schwann cells themselves. We analyze the interactions between this putative autocrine death signal and previously defined paracrine and autocrine survival signals and show that expression of a dominant negative c-Jun inhibits TGF beta -induced apoptosis. This and other findings pinpoint activation of c-Jun as a key downstream event in TGF beta -induced Schwann cell death. The ability of TGF beta to kill Schwann cells, like normal Schwann cell death in vivo, is under a strong developmental regulation, and we show that the decreasing ability of TGF beta to kill older cells is attributable to a decreasing ability of TGF beta to phosphorylate c-Jun in more differentiated cells

Numerical Construction of LISS Lyapunov Functions under a Small Gain Condition

In the stability analysis of large-scale interconnected systems it is frequently desirable to be able to determine a decay point of the gain operator, i.e., a point whose image under the monotone operator is strictly smaller than the point itself. The set of such decay points plays a crucial role in checking, in a semi-global fashion, the local input-to-state stability of an interconnected system and in the numerical construction of a LISS Lyapunov function. We provide a homotopy algorithm that computes a decay point of a monotone op- erator. For this purpose we use a fixed point algorithm and provide a function whose fixed points correspond to decay points of the monotone operator. The advantage to an earlier algorithm is demonstrated. Furthermore an example is given which shows how to analyze a given perturbed interconnected system.Comment: 30 pages, 7 figures, 4 table

Is there a gender gap in CEO compensation?

The gender pay gap generates significant political and social debate. This study contributes to this discussion by examining if a gender pay gap exists at the highest level of corporate management, the CEOs. While previous studies have documented a gender pay gap for most levels of executives the findings with respect to CEOs are conflicting. In this paper we focus only on CEO's as it is the most homogenous of executive roles and does not require us to assume that executives with similar titles undertake identical roles. Our evidence is based on 291 US firm-years for the period of 1998-2010. We do not find any association between CEO pay and gender using both the total sample and a sample matched using propensity scores to control for firm characteristics. These insignificant results hold for total pay, salary and bonuses, and for different matching procedures and econometric specifications. Our results therefore indicate that women who rise through the "glass ceiling" to the level of CEO are remunerated at similar levels to their male counterparts. © 2012 Elsevier B.V.

Powerful CEOs, cash bonus contracts and firm performance

© 2019 John Wiley & Sons Ltd We investigate whether powerful chief executive officers (CEOs) influence the conditions of their cash bonus contracts. Specifically, we examine (i) the association between CEO power and the proportion of ex-ante cash bonus to base salary (bonus ratio), (ii) the association between CEO power and the relative use of non-financial to financial performance targets in cash bonus contracts, and (iii) the performance consequences of incorporating non-financial targets in cash bonus contracts. Results show that powerful CEOs are associated with greater ex-ante bonus ratios and higher proportions of non-financial performance targets compared to less powerful CEOs. Furthermore, the use of quantitative and corporate social responsibility (CSR)-related non-financial performance targets is positively associated with subsequent firm performance, and the use of undefined non-financial performance targets is negatively associated with subsequent firm performance. These results are robust to alternative econometric specifications and variable definitions

Insolation triggered abrupt weakening of Atlantic circulation at the end of interglacials.

Abrupt cooling is observed at the end of interglacials in many paleoclimate records, but the mechanism responsible remains unclear. Using model simulations, we demonstrate that there exists a threshold in the level of astronomically induced insolation below which abrupt changes at the end of interglacials of the past 800,000 years occur. When decreasing insolation reaches the critical value, it triggers a strong, abrupt weakening of the Atlantic meridional overturning circulation and a cooler mean climate state accompanied by high-amplitude variations lasting for several thousand years. The mechanism involves sea ice feedbacks in the Nordic and Labrador Seas. The ubiquity of this threshold suggests its fundamental role in terminating the warm climate conditions at the end of interglacials

Magnetism and Charge Dynamics in Iron Pnictides

In a wide variety of materials, such as copper oxides, heavy fermions, organic salts, and the recently discovered iron pnictides, superconductivity is found in close proximity to a magnetically ordered state. The character of the proximate magnetic phase is thus believed to be crucial for understanding the differences between the various families of unconventional superconductors and the mechanism of superconductivity. Unlike the AFM order in cuprates, the nature of the magnetism and of the underlying electronic state in the iron pnictide superconductors is not well understood. Neither density functional theory nor models based on atomic physics and superexchange, account for the small size of the magnetic moment. Many low energy probes such as transport, STM and ARPES measured strong anisotropy of the electronic states akin to the nematic order in a liquid crystal, but there is no consensus on its physical origin, and a three dimensional picture of electronic states and its relations to the optical conductivity in the magnetic state is lacking. Using a first principles approach, we obtained the experimentally observed magnetic moment, optical conductivity, and the anisotropy of the electronic states. The theory connects ARPES, which measures one particle electronic states, optical spectroscopy, probing the particle hole excitations of the solid and neutron scattering which measures the magnetic moment. We predict a manifestation of the anisotropy in the optical conductivity, and we show that the magnetic phase arises from the paramagnetic phase by a large gain of the Hund's rule coupling energy and a smaller loss of kinetic energy, indicating that iron pnictides represent a new class of compounds where the nature of magnetism is intermediate between the spin density wave of almost independent particles, and the antiferromagnetic state of local moments.Comment: 4+ pages with additional one-page supplementary materia

Beat-to-beat ambulatory blood pressure estimation based on random forest

Ambulatory blood pressure is critical in predicting some major cardiovascular events; therefore, cuff-less and noninvasive beat-to-beat ambulatory blood pressure measure-ment is of great significance. Machine-learning methods have shown the potential to derive the relationship between physio-logical signal features and ABP. In this paper, we apply random forest method to systematically explorer the inherent connections between photoplethysmography signal, electrocardiogram signal and ambulatory blood pressure. To archive this goal, 18 features were extracted from PPG and ECG signals. Several models with most significant features as inputs and beat-to-beat ABP as outputs were trained and tested on data from the Multi-Parameter Intelligent Monitoring in Intensive Care II database. Results indicate that compared with the common pulse transit time method, the RF method gives a better performance for one-hour continuous estimation of diastolic blood pressure and systolic blood pressure under both the Association for the Advancement of Medical Instrumentation and British Hyper-tension Society standard

Potential suppressive effects of Mexican poppy weed residues on germination and early growth of maize and pearl millet crops

Argemone ochroleuca allelochemical properties have been reported but not empirically tested on economically important staple cereal crops. Therefore, the objective of this study was to determine the potential Allelopathic effects of the alien weed’s residues on germination and early-growth of maize (Zea mays L.) and Pearl millet (Pennisertum glaucum). Allelopathic effects of A. ochroleuca on maize and millet seed germination were tested in a 2 (shoot and root) x 11 (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100g/L water) factorial treatment arrangement in CRD in an incubator placed in a laboratory. Whereas effects of the weed extracts on the same crops’ early-growth were tested in a 2 (shoot and roots) x 8 (0, 2, 4, 6, 8, 10, 12 and 14g ground-powdered extracts) factorial arrangement in RCBD under laboratory conditions. Maize and millet germination percentage, germination speed, mean germination time, mean daily germination, plumule and radicle length were measured for germination test, whereas, plant height, stem diameter, root and shoot mass were used as indicators of A. ochroleuca suppression of early plant growth. Relative to untreated control, concentration equal to and greater than 10g/L aqueous extracts of A. ochroleuca reduced millet and maize seed germination variables by 10–100% and 28–56%, respectively, while early-growth variables were reduced by 66–100% and 4–37%, respectively. Argemone ochroleuca shoot extracts were more suppressive than root extracts on germination and early growth of the two crops. In conclusion, A. ochroleuca Allelopathic effects were concentration and plant-part dependent, inhibitory effects increased with concentrations, with extracts from shoots being more Allelopathic on measured variables when compared to root extracts. As A. ochroleuca continues to spread yearly without any control strategies in place, a threat exist on maize and Pearl millet production especially in communal farming areas where improved management strategies are non- existent.&nbsp

Stress-strain characteristic of SFRC using recycled fibres

This paper presents work from a comprehensive study on the development of a flexural design framework for concrete reinforced with steel fibres that are recovered from used tyres. The experimental flexural behaviour of notched concrete prisms reinforced with these fibres is initially presented. For comparison purposes, prisms reinforced with industrially produced fibres are also considered. An attempt to adopt an existing RILEM design framework to derive appropriate tensile stress-strain blocks is made, but problems are identified with key parameters of the framework. The influence of crack propagation and location of neutral axis depth on the tensile stress distribution is examined. Following an analytical study, it is concluded that the uniaxial stress-strain model, proposed by RILEM overestimates the load-carrying capacity and should be modified by utilising more advanced analytical techniques. © RILEM 2006

Cholangiocarcinoma: spectrum of appearances on Gd-EOB-DTPA-enhanced MR imaging and the effect of biliary function on signal intensity

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