672 research outputs found
Biological activities of in vitro liverwort Marchantia polymorpha L. extracts
To overcome the problems in liverwort collecting such as small size and easily mixed with other species in the wild, we have successfully cultivated Marchantia polymorpha L. under in vitro conditions in the previous study. The aim of this study is to evaluate the biological activities of this in vitro biomass as a confirmation of the sufficient protocol in cultivation this species. Cultured biomass was dried at a temperature of 45-50 oC to constant weight and ground into a fine powder. The coarse powder was extracted with organic solvents of increasing polarization including n-hexane, chloroform, ethyl acetate, and ethanol using the maceration technique. Four extracts were investigated antioxidant (iron reduction power, DPPH), antibacterial (agar diffusion), tyrosinase inhibitory activity, anti-proliferation on MCF-7 cells. Additionally, the presence of natural metabolite groups of the extracts was detected by using specific reagents. For antioxidant activity, ethyl acetate fraction extract had the highest iron reducing power and DPPH free radical scavenging ability with IC50 = 439.31 µg ml-1. All three n-hexane, chloroform, and ethyl acetate extracts possessed resistance to the bacterial strain tested. At a concentration of 2 mg ml-1, n-hexane and chloroform extracts had the highest percentage of tyrosinase inhibition (69.54 and 69.10%, respectively). The n-hexane extract is a potent extract that inhibits the proliferation of MCF-7 cells with the lowest IC50 of 38.15 µg ml-1. A preliminary chemical composition survey showed that the cultured biomass liverwort contains many bioactive compounds, particularly the compounds of range of non- and less-polarized fractions
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On the importance of golden parachutes
In acquisitions, target chief executive officers (CEOs) face a moral hazard: Any personal gain from the deal could be offset by the loss of the future compensation stream associated with their jobs. Larger, more important parachutes provide greater relief for these losses. To explicitly measure the moral hazard target CEOs face, we standardize the parachute payment by the expected value of their acquisition-induced lost compensation. We examine 851 acquisitions from 1999–2007, finding that more important parachutes benefit target shareholders through higher completion probabilities. Conversely, as parachute importance increases, target shareholders receive lower takeover premia, while acquirer shareholders capture additional rents from target shareholders
An investigation of the evidence of benefits from climate compatible development
Climate change is likely to have profound effects on developing countries both through the climate impacts experienced, but also through the policies, programmes and projects adopted to address climate change. Climate change mitigation (actions taken to reduce the extent of climate change), adaptation (actions taken to ameliorate the impacts), and on-going development are all critical to reduce current and future losses associated with climate change, and to harness gains. In the context of limited resources to invest in climate change, policies, programmes, or projects that deliver ‘triple wins’ (i.e. generating climate adaptation, mitigation and development benefits) – also known as climate compatible development – are increasingly discussed by bilateral and multilateral donors. Yet there remains an absence of empirical evidence of the benefits and costs of triple win policies. The purpose of this paper is therefore to assess evidence of ‘triple wins’ on the ground, and the feasibility of triple wins that do not generate negative impacts. We describe the theoretical linkages that exist between adaptation, mitigation and development, as well as the trade-offs and synergies that might exist between them. Using four developing country studies, we make a simple assessment of the extent of climate compatible development policy in practice through the lens of ‘no-regrets’, ‘low regrets’ and ‘with regrets’ decision making. The lack of evidence of either policy or practice of triple wins significantly limits the capacity of donors to identify, monitor or evaluate ‘triple wins at this point in time. We recommend a more strategic assessment of the distributional and financial implications of 'triple wins' policies
Federated Deep Reinforcement Learning-based Bitrate Adaptation for Dynamic Adaptive Streaming over HTTP
In video streaming over HTTP, the bitrate adaptation selects the quality of
video chunks depending on the current network condition. Some previous works
have applied deep reinforcement learning (DRL) algorithms to determine the
chunk's bitrate from the observed states to maximize the quality-of-experience
(QoE). However, to build an intelligent model that can predict in various
environments, such as 3G, 4G, Wifi, \textit{etc.}, the states observed from
these environments must be sent to a server for training centrally. In this
work, we integrate federated learning (FL) to DRL-based rate adaptation to
train a model appropriate for different environments. The clients in the
proposed framework train their model locally and only update the weights to the
server. The simulations show that our federated DRL-based rate adaptations,
called FDRLABR with different DRL algorithms, such as deep Q-learning,
advantage actor-critic, and proximal policy optimization, yield better
performance than the traditional bitrate adaptation methods in various
environments.Comment: 13 pages, 1 colum
Health-related quality of life and well-being in people over 75 years of age with end-stage kidney disease managed with dialysis or comprehensive conservative care: A cross-sectional study in the UK and Australia
© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Objective To measure health-related quality of life (HRQoL) and well-being in older people with end-stage kidney disease (ESKD) and to determine the association between treatment type and sociodemographic characteristics on these outcome measures. In addition, to assess the convergent validity between the HRQoL and well-being measure and their feasibility and acceptability in this population. Design Prospective cross-sectional study. Setting Three renal units in the UK and Australia. Participants 129 patients with ESKD managed with dialysis or with an estimated glomerular filtration ≤10 mL/min/1.73 m 2 and managed with comprehensive conservative, non-dialytic care. Outcome measures HRQoL and well-being were assessed using Short-Form six dimensions (SF-6D, 0-1 scale); Kidney Disease Quality of Life (KDQOL-36) (0-100 scale) and Investigating Choice Experiments Capability Measure-Older people (ICECAP-O, 0-1 scale). Linear regression assessed associations between treatment, HRQoL and well-being. Pearson's correlation coefficient assessed convergent validity between instruments. Results Median age of 81 years (IQR 78-85), 65% males; 83 (64%) were managed with dialysis and 46 (36%) with conservative care. When adjusted for treatment type and sociodemographic variables, those managed on dialysis reported lower mean SF-6D utility (-0.05, 95% CI-0.12 to 0.01); lower KDQOL Physical Component Summary score (-3.17, 95% CI-7.61 to 1.27); lower Mental Component Summary score (-2.41, 95% CI-7.66 to 2.84); lower quality of life due to burden (-28.59, 95% CI-41.77 to-15.42); symptoms (-5.93, 95% CI-14.61 to 2.73) and effects of kidney disease (-16.49, 95% CI-25.98 to-6.99) and lower overall ICECAP-O well-being (-0.07, 95% CI-0.16 to 0.02) than those managed conservatively. Correlation between ICECAP-O well-being and SF-6D utility scores was strong overall, 0.65 (
Assessment of seasonal winter temperature forecast errors in the regcm model over northern Vietnam
This study verified the seasonal six-month forecasts for winter temperatures for northern Vietnam in 1998–2018 using a regional climate model (RegCM4) with the boundary conditions of the climate forecast system Version 2 (CFSv2) from the National Centers for Environmental Prediction (NCEP). First, different physical schemes (land-surface process, cumulus, and radiation parameterizations) in RegCM4 were applied to generate 12 single forecasts. Second, the simple ensemble forecasts were generated through the combinations of those different physical formulations. Three subclimate regions (R1, R2, R3) of northern Vietnam were separately tested with surface observations and a reanalysis dataset (Japanese 55-year reanalysis (JRA55)). The highest sensitivity to the mean monthly temperature forecasts was shown by the land-surface parameterizations (the biosphere−atmosphere transfer scheme (BATS) and community land model version 4.5 (CLM)). The BATS forecast groups tended to provide forecasts with lower temperatures than the actual observations, while the CLM forecast groups tended to overestimate the temperatures. The forecast errors from single forecasts could be clearly reduced with ensemble mean forecasts, but ensemble spreads were less than those root-mean-square errors (RMSEs). This indicated that the ensemble forecast was underdispersed and that the direct forecast from RegCM4 needed more postprocessing
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Frenemies: how do financial firms vote on their own kind?
The financial sector is unique in being largely self-governed: the majority of financial firms’ shares are held by other financial institutions. This raises the possibility that monitoring of financial firms is especially undermined by conflicts of interest due to personal and professional links between these firms and their shareholders. To investigate this possibility, we scrutinize the aspect of the financial sector’s self-governance that is directly observable: mutual fund companies’ voting of their peers’ stock. We find that considerations specific to investee firms’ membership in the same industry as their investors do indeed impact voting. This impact is in the direction of supporting the investee’s management. We show that the own-industry effect reduces director efficacy and lowers firm value as a result. We extend our analysis to other financial companies and show that they also tend to vote more favorably when it comes to their peers. Our results suggest that peer support is a corrupting factor in the financial sector’s governance
Titanium dioxide - activated carbon composite for photoelectrochemical degradation of phenol
In this study, titanium dioxide (TiO2) and titanium dioxide – activated carbon composite (TiO2–AC) were prepared by sol-gel method for photoelectrochemical (PEC) applications. Characterization of the materials was performed by scanning electron microscope, energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and diffuse reflectance spectroscopy. The results show that TiO2 was successfully loaded on activated carbon (AC), producing TiO2–AC with 2.61 eV of bandgap energy, lower than that of TiO2 (3.15 eV). Photoanodes based on TiO2 and TiO2–AC were fabricated and applied to PEC experiments for phenol degradation. In comparison with the TiO2 photoanode, the TiO2–AC one exhibited superior photocatalytic activity, which was indicated by a high current density and effective phenol removal. A mechanism of phenol PEC degradation on the TiO2–AC photoanode was proposed, which includes interaction between protonated phenol and active sites bearing oxygen on the photoanode surface. A kinetic model according to this mechanism was also established and fitted to experimental findings, resulting in rate constants of elementary reactions
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