422 research outputs found
Climate Change Education Engagement in Annex I Partiesā National Communications Within the United Nations Framework Convention on Climate Change
Drawing data on 44 Annex I Partiesā National Communications (NCs) within the United Nations Framework Convention of Climate Change (UNFCCC), this research conducts document analysis on Annex I Partiesā engagement with practices and policies related to Action for Climate Empowerment (ACE), including signs of the assumptions of economic orientations, ways of learning, and human-nature relationships. Apart from Climate Change Education (CCE)/ACEās integration into formal education, extra-curricular learning programs are reported intensively in the NCs. In non-formal and informal education, the ACE engagement is reported in the content to various ACE elements. The assumptions on a green-economy economic orientation, a neoliberal economic orientation, an instrumental learning, a participatory learning, an ecologically centered human-nature relationship, and a resourcist human-nature relationship are present in the NCs, with two economic orientations being the most identified assumptions. Further research is recommended, especially in the CCE/ACE engagement in the public sphere through non-formal and informal approaches
Understanding the physical and biological effects of dust-induced insect death
Background
Quality and quantity of stored grain is constantly changing due to insect and fungal activity. The efficacy of storage method dictates the quality of grain. Traditional chemical pesticides, though effective, were often criticised for issues like increasing insect resistance, chemical residue, environmental contamination and human health risk. The diatomaceous earth based formulations could reduce chemical pesticides usage at some extent. But the slow insect killing and being non-food grade limited wide application. The high recommended dosage (500 to 3500 ppm) results in several adverse effects on grain, including reduce in the flow ability and bulk density, visible residue, extra dust generation during processing. Synthetic amorphous silica (SAS) consists three types: pyrogenic, precipitated, surface-treated SAS. These dusts can be distinguished from natural amorphous silica such as diatomaceous earth by its high chemical purity, the finely particulate nature and characteristics of particles. All types of SAS have been widely used in topical and oral medicines, food and cosmetics for many decades without evidence of adverse human health risks. Based on extensive physico-chemical, ecotoxicology, human health and epidemiology data, SAS as non-chemical method for pest management is revolutionary and advantageous compared to traditional approaches. However, their insecticidal mechanism is poorly understood. The optimal application protocol is not developed. This study described a comprehensive investigation of insecticidal mechanism of SAS particles and their application as an alternative practical stored grain pest control method.
Results
The first study was aimed to investigate the efficacy of different synthetic amorphous silica (SAS) powders against different insect species at multiple developmental stages compared with diatomaceous earth (DE). The stationary stages, egg and pupa, were more tolerant than that of the mobile stages, larva and adult, upon SAS and DE exposure. The insect infestation cannot be completely control by all the SAS and DE. A 100% of hatching rate was observed and more than 32% of pupa emerged in all the dust treated groups. Larva stage was most susceptible to the SAS and DE. Newly emerged adults were more susceptible to SASs and DE than older adults. The outcome for larvae was opposite. Among the three insect species adults, when treated by SAS and DE, T. castaneum was the most tolerant species and C. ferrugineus was the most susceptible. The efficacy of SAS against insects was higher than that of DE. Among of SASs, precipitated SAS performed better than pyrogenic SAS in term of mortality. Hydrophobic SAS powders were more effective against T. castaneum adult, while hydrophilic SAS powders were more effective against T. castaneum larvae, pupae and Sitophilus oryzae adults.
We evaluated the physical property of aforementioned SAS and DE in relation to efficacy. SAS powders have higher specific surface area, total pore volume, oil sorption capacity and smaller particle size than DE. In term of the SAS powders produced by different methods, pyrogenic SAS powders had higher oil sorption capacity but lower total pore volume and specific surface area, and larger particle size than precipitated SAS. Comparing with hydrophilic SAS, the particle size of hydrophobic SAS was smaller while has lower oil sorption capacity. There was a significant relationship between physical property of powder and insecticidal efficacy in SAS without a specific index.
We developed and evaluated a rapid screening protocol to identify electrostatic charge dictates attachment processes during initial contact between SAS and insects. The charge ability of three major stored grain insects, Sitophilus oryzae, Tribolium castaneum and Cryptolestes ferrugineus and four hydrophilic precipitated SAS and one DE was assessed on two insulated surfaces filter paper and glass. After contact with insulation surfaces, synthetic amorphous silica (SAS) and DE carry negative charges due to attaining electrons from insulation surfaces, while stored product insects carry charges of opposite polarity from electron loss. According to Coulombās law, the SAS particles would then be passively attracted by insect via the mere effect of electrostatic forces. A linear correlation was observed between electrostatic charge and bioactivity of dust.
After exposure to SAS, the changes in water content and other physiological components of insects led to changes in coloration and gross appearance. The heterogeneous distribution made visual comparisons difficult. Hyperspectral imaging systems with optically tuneable filters can record images at hundreds of contiguous wavelengths (narrow spectral resolution) in the form of a hypercube (three-dimensional hyperspectral data). Hyperspectral imaging coupled with back propagation neural network models was employed to quantify differences in parameters which reflected the response of T. castaneum and S. oryzae to hydrophobic and hydrophilic precipitated SAS. The presence of SAS on ventral and dorsal cuticle of two insect species caused differential values of relative reflectance in visible and short-wave near-infrared ranges. The control samples of all groups were correctly classified by BPNN model and misclassification occurred only with the two SAS treated. These results suggested that the differences in absorption characteristics of cuticular fat and protein contributed to the varied performance. The recognition rate between two SAS treated was within the acceptable identification range. This suggested that both SASs have similar effect on insect with varied degree.
We investigated how these two hydrophobic and hydrophilic precipitated SASs physically influenced insect in intersegmental membrane and their biological effects. Both SASs rapidly reduced insect locomotion to the limiting value within 3.5 hours and 12 hours for S. oryzae and T. castaneum, respectively. In addition, we found that there was significant differential decrease in straightness and upward length which were used as parameters to evaluate insect behaviours. Environmental scanning electron microscope (ESEM) images and data of stride length directly exhibited SAS eroded insect intersegmental membrane and absorbed the vital body fluid, eventually caused irreversible structural damage. The hydrophilic SAS was more effective in changing these parameters in S. oryzae, while hydrophobic SAS was more effective in T. castaneum. Male population was more susceptible than female.
We further evaluated the efficacy of SAS structural treatment combined with a new integrated trap as insect control in the field trial. Insect infestation was monitored by integrated trap utilising insect behaviours. Prior to SAS treatment, five integrated traps captured 1722 g insect inside a warehouse in seven day. Synthetic amorphous silica was aerogelize and dispersed uniformly in different locations of the warehouse. The mortality of five major species of stored grain insect adults reached 100% within three days post exposure.
Conclusion
SAS powders are food-grade, quick, effective, low cost and easy to apply as an insect control method. They donāt have the disadvantages of traditional chemical pesticide regarding to occupational health, environmental and safety concern. Detecting the electrostatic charge is an effective protocol for SAS efficacy evaluation. As an emerging non-destructive and reagent-less analytical technique, hyperspectral imaging proved to be highly efficient in pesticidal effect evaluation. Intersegmental membrane is a promising target site for new inert dust pesticide products
The UK equity unit trusts : time-varying market risk and idiosyncratic risk
PhD ThesisThis thesis empirically investigates the risk of UK equity unit trusts by breaking down the total risk of trusts into market risk and idiosyncratic risk. This thesis constructs a research sample of 478 UK-authorized equity unit trusts from July 1990 to June 2015, exploring three research questions: the investment abilities of stock-picking and market return-timing; the investment ability of market volatility-timing and joint market timing; the idiosyncratic risk at the individual trust level.
This thesis uses daily data to capture intermittent timing behavior and employs GARCH-type models to address the econometric problems of autocorrelation and heteroscedasticity owing to the employment of daily returns. This thesis documents how trust managers can time the market volatility successfully, whereas this is less the case with how they time the market returns. Moreover, data frequency cannot explain the empirical findings of reverse return-timing behavior. Volatility-timing evaluation is sensitive to data frequency, indicated by the opposite results obtained from daily and monthly data analysis.
Trust managers select stocks to construct their portfolios. Stockās idiosyncratic risk related to firm news and unpriced by market returns deserve as much attention as market risk. Our last study concentrates on the idiosyncratic risk of unit trustsā portfolio that highly depends on trust managers stock-picking decisions. The study breaks down each trustās total idiosyncratic risk into aggregate idiosyncratic risk capturing typical responses of trust managers to the public firm news and trust-specific unique risk assessing the risk-taking decision of each unit trust manager.
We emphasise the relationship between realized returns of the unit trust and its unique risk exploring whether trust managers can produce high returns for trust investors when they take relatively high additional risk comparing to peers. The finding of significant positive relationship in the short-term across all trusts is favourable, supporting that managers are rewarded for their aggressive investment. Our finding can advise trust investors to invest in unit trusts with relatively high risk within their risk tolerance and capability. The positive relationship, nevertheless, is not consistent; thus, it is essential for investors to timely switch unit trusts timely
Crack Risk Evaluation of Early Age Concrete Based on the Distributed Optical Fiber Temperature Sensing
Cracks often appear in concrete arch dams, due to the thermal stress and low tensile strength of early age concrete. There are three commonly used temperature controlling measures: controlling the casting temperature, burying cooling pipe, and protecting the surface. However, because of the difficulty to obtain accurate temperature and thermal stress field of the concrete, the rationality and economy of these measures are not assessed validly before and after construction. In this paper, a crack risk evaluation system for early age concrete is established, including distributed optical fiber temperature sensing (DTS), prediction of temperature and stress fields, and crack risk evaluation. Based on the DTS temperature data, the back-analysis method is applied to retrieve the thermal parameters of concrete. Then, the temperature and thermal stress of early age concrete are predicted using the reversed thermal parameters, as well as the laboratory test parameters. Finally, under the proposed cracking risk evaluation principle, the cracking risk level of each concrete block is given; the preliminary and later temperature controlling measures were recommended, respectively. The application of the proposed system in Xiluodu super high arch dam shows that this system works effectively for preventing cracks of early age concrete
Downlink and Uplink Intelligent Reflecting Surface Aided Networks: NOMA and OMA
Intelligent reflecting surfaces (IRSs) are envisioned to provide
reconfigurable wireless environments for future communication networks. In this
paper, both downlink and uplink IRS-aided non-orthogonal multiple access (NOMA)
and orthogonal multiple access (OMA) networks are studied, in which an IRS is
deployed to enhance the coverage by assisting a cell-edge user device (UD) to
communicate with the base station (BS). To characterize system performance, new
channel statistics of the BS-IRS-UD link with Nakagami- fading are
investigated. For each scenario, the closed-form expressions for the outage
probability and ergodic rate are derived. To gain further insight, the
diversity order and high signal-to-noise ratio (SNR) slope for each scenario
are obtained according to asymptotic approximations in the high-SNR regime. It
is demonstrated that the diversity order is affected by the number of IRS
reflecting elements and Nakagami fading parameters, but the high-SNR slope is
not related to these parameters. Simulation results validate our analysis and
reveal the superiority of the IRS over the full-duplex decode-and-forward
relay.Comment: Accepted for publication in the IEEE Transactions on Wireless
Communication
Exploring the communication effects of signals and messages in the COVID-19 health crisis
The ongoing coronavirus disease 2019 (COVID-19) pandemic presents an unprecedented global public health crisis. In this scenario, crisis communication on social media that largely influences peopleās emotions, attitudes and interaction behaviours towards a large-scale public health crisis plays a critical role in persuading the publicās behaviour adjustment and coping with the risk. The effects of crisis communication strategies and signals embedded in social media topics and messages warrant further investigation. This study explored and tested the communication effects of crisis messages and topics from the initial event stage to the normalized control stage of the COVID-19 crisis using texts scraped from a Chinese social media website, namely Weibo. Natural language processing (NLP) techniques, i.e., sentiment and emotion analysis, positivist text coding, and ordinary least squares (OLS) were used in data analysis. This study contributes to the crisis management literature and theories by identifying and testing a number of factors and signals in crisis communication on social media that influence receiversā reactions and behaviours. In doing so, this study provides suggestions for practitioners and policymakers on effective communication of the crisis situation and prevention behaviours to the public
Portfolio Insurance Strategies under Volatile Market
Portfolio insurance strategies are designed to enable investors to limit downside risk while at the same time to gain profits from rising market. Among that, constant proportion portfolio insurance strategy (CPPI) and option-based portfolio insurance strategy (OBPI) are two typical strategies in portfolio insurance strategies. With the popularity of the portfolio insurance strategies, portfolio optimization problem receives plenty of publicity. Each investor has their own preference for return and risk, investment activities should follow a utility function of return and risk. Therefore, portfolio optimization problem can be modeled as expected utility maximization problems. It is well-known that in the Black-Scholes model, these strategies can be implemented as the optimal solution by forcing an exogenously given guarantee to maximize the expected utility of investors with constant relative risk aversion (CRRA) function. In this research, we combine CRRA utility maximization with the stylized strategies and bring these results together. In particular, we focus on the volatile market and consider the market is under the Constant Elasticity of Variance (CEV) model. In addition, we discuss the advantages and disadvantages of CPPI and OBPI strategies under the distribution of terminal wealth process and utility value in CEV model
Total flavonoids from Ganshanbian (Herba Hyperici Attenuati) effect the expression of CaL-Ī±1C and KATP-Kir6.1 mRNA of the myocardial cell membrane in myocardial ischemia-reperfusion arrhythmia rats
AbstractObjectiveTo observe the impact of total flavonoids from Ganshanbian (Herba Hyperici Attenuati) on the expression of vascular smooth muscle membrane L-type calcium channel alpha1 C subunit (CaL-Ī±1C) and ATP-sensitive K+ channel (KATP)-Kir6.1 mRNA, and explore the mechanisms of the antiarrhythmic effect of Ganshanbian (Herba Hyperici Attenuati) total flavonoids.MethodsThe treatment group was fed total flavonoids from Ganshanbian (Herba Hyperici Attenuati) for 7 days by gavage with 100 mg Ā· kgā1 Ā· dā1. The blank control group and model control group were given the same amount of normal saline for 7 d. Arrhythmias were induced by performing a myocardial ischemia-reperfusion and electrocardiogram was observed. Reverse transcription-polymerase chain reaction was used to detect the expression of CaL-Ī± 1Cand KATP-Kir6.1 mRNA in the myocardial cell membrane of all groups of rats.ResultsTotal flavonoids from Ganshanbian (Herba Hyperici Attenuati) can delay the appearance of myocardial ischemia reperfusion arrhythmias, shorten the duration of myocardial ischemia reperfusion arrhythmias, reduce heart rate, reduce cell membrane expression of CaL-Ī±1C mRNA and enhance the expression of KATP-Kir6.1 mRNA in myocardial ischemia-reperfusion arrhythmic rats.ConclusionTotal flavonoids from Ganshanbian (Herba Hyperici Attenuati) can alleviate arrhythmias by affecting the expression of L-type calcium channels and ATP-sensitive K+ channels
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