Estimating Functions and Equations: An Essay on Historical Developments with Applications to Econometrics

The idea of using estimating functions goes a long way back, at least to Karl Pearson's introduction to the method of moments in 1894. It is now a very active area of research in the statistics literature. One aim of this chapter is to provide an account of the developments relating to the theory of estimating functions. Starting from the simple case of a single parameter under independence, we cover the multiparameter, presence of nuisance parameters and dependent data cases. Application of the estimating functions technique to econometrics is still at its infancy. However, we illustrate how this estimation approach could be used in a number of time series models, such as random coefficient, threshold, bilinear, autoregressive conditional heteroscedasticity models, in models of spatial and longitudinal data, and median regression analysis. The chapter is concluded with some remarks on the place of estimating functions in the history of estimation.

Antimicrobial and antioxidative activities in the bark extracts of Sonneratia caseolaris, a mangrove plant

The present study deals with the phytochemical contents, antimicrobial and antioxidative activities of bark tissue of Sonneratia caseolaris, a mangrove plant from Sundarban estuary, India. Phytochemical analyses revealed the presence of high amounts of phenolics, flavonoids, tannins, alkaloids and saponins. Antimicrobial efficacies of various extracts of S. caseolaris were assessed by disc diffusion method against two Gram-positive (Bacillus subtilis and Bacillus coagulans), two Gram-negative (Escherichia coli and Proteus vulgaris) bacteria and one fungus (Saccharomyces cerevisiae). The methanolic extract among others showed significant minimum inhibitory concentration (MIC) values. The antioxidant activity as indicated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of the bark tissue extract from the species was found to be quite appreciable. The extracts were found to retain their antimicrobial activities despite pH and thermal treatments, thus indicating the stability of their activity even at extreme conditions. The antioxidant activity was also found to be considerably stable after thermal treatments. The components of the tissue extracts were subjected to separation using thin layer chromatography (TLC). The constituents with antimicrobial and antioxidative properties were identified using TLC-bioautography by agar-overlay and DPPH spraying methods respectively. A number of bioactive constituents with antimicrobial and radical scavenging properties were observed on the developed bioautography plate. The fractions with antimicrobial properties were isolated from the reference TLC plates and subjected to gaschromatography-mass spectrometry (GC-MS) analysis for partial characterization and identification of the metabolites that might be responsible for the activities. The study suggests Sonneratia caseolaris bark as a potential source of bioactive compounds with stable antimicrobial and antioxidative properties and can be used as natural antimicrobial/antioxidative agents in clinical, pharmaceutical and food processing industries

Persistence of ex-ante volatility and the cross-section of stock returns

We suggest a new measure of total ex-ante volatility () in stock returns, which includes traditional non-market (or idiosyncratic) risk and the unexpected component of market return. We find that the portfolio-level measure exhibits strong predictive power for the cross-section of average returns during the post-1963 period. We demonstrate that (1) the persistence of gives rise to economically significant spread in returns between value and growth stocks, and (2) the cross-sectional dispersion in stock returns is positively related to the estimated value of . The benefit of the measure is that it is countercyclical and contains relevant information about the time-variation in value premium

Partial purification and characterization of an antimicrobial activity from the wood extract of mangrove plant Ceriops decandra

The development of resistance towards the antibiotics in use today has been a source of growing concern in the modern healthcare system around the world. To counter this major threat, there is an urgent need for discovery of new antimicrobials. Many plants, like mangroves, possess highly diversified list of natural phytochemicals which are known to have wide range of bioactivities. These phytochemicals can be good sources for the discovery of new drugs. In this study, we report the partial phytochemical characterization and antimicrobial activities of a semi-purified fraction isolated from the wood tissue of Ceriops decandra, a mangrove plant. This fraction named CD-3PM was chromatographically separated from C. decandra wood extract and was subjected to different spectral analyses to determine its partial chemical nature. The structural investigation indicates the presence of two diterpenoids, i) 3β, 13β-Dihydroxy-8-abietaen-7-one and ii) 3β-Hydroxy-8,13-abietadien-7-one in the CD-3PM fraction. The antimicrobial potential of this fraction was evaluated by microdilution-MTT assay against several organisms. Among the nine microorganisms found to be sensitive to the CD-3PM fraction, six organisms are reported to be pathogenic in nature. The CD-3PM fraction with broad spectrum antimicrobial efficacy revealed the presence of two diterpenoids and possesses potential applications in drug discovery process and food processing industries

LIVE STREAMING OPTIMIZER AT UPF USING INTELLIGENT APPLICATION AND FLOW DETECTION

With Mobile Edge Computing (MEC) in 5G, the User Plane Function (UPF) has moved closer to the end user. This movement, however, has not eliminated the latency incurred to cover the hops to reach the Application Function (AF). As a result, the internet protocol (IP) core design is of utmost consequence, so that content may be reached with minimal hops. This would imply that service providers would need to incur heavy costs redesigning networks from legacy technology to next generation 5G technology. A path to this overhaul is needed. The solution presented herein may allow service providers to continue using their legacy infrastructure for streaming while at the same time supporting 5G performance. The solution is directed to algorithms to detect live streaming candidates for live streaming optimization and replicate the same content

The value premium, aggregate risk innovations, and average stock returns

We test whether innovations in aggregate risk, interpolated from a vector autoregressive system that contains the Chen, Roll and Ross (1986) five factors as in Petkova (2006), are common factors in cross-sectional stock returns. We provide direct evidence that innovation in industrial production growth, a classical business-cycle variable that summarizes the state of the economy, is associated with the cross-sectional return predictability of individual stocks. We conclude that the role of innovation in aggregate risk is not random, and furthermore that it provides guidance concerning an important source of nonfinancial market-based risk in asset returns

Why we must question the militarisation of conservation

Concerns about poaching and trafficking have led conservationists to seek urgent responses to tackle the impact on wildlife. One possible solution is the militarisation of conservation, which holds potentially far-reaching consequences. It is important to engage critically with the militarisation of conservation, including identifying and reflecting on the problems it produces for wildlife, for people living with wildlife and for those tasked with implementing militarised strategies. This Perspectives piece is a first step towards synthesising the main themes in emerging critiques of militarised conservation. We identify five major themes: first, the importance of understanding how poaching is defined; second, understanding the ways that local communities experience militarised conservation; third, the experiences of rangers; fourth, how the militarisation of conservation can contribute to violence where conservation operates in the context of armed conflict; and finally how it fits in with and reflects wider political economic dynamics. Ultimately, we suggest that failure to engage more critically with militarisation risks making things worse for the people involved and lead to poor conservation outcomes in the long run

Informação Endógena, Caracterização do Risco e Retornos de Ações Variantes no Tempo

In this paper we provide a new type of risk characterization of the predictability of two widely known abnormal patterns in average stock returns: momentum and reversal. The purpose is to illustrate the relative importance of common risk factors and endogenous information. Our results demonstrates that in the presence of zero-investment factors, spreads in average momentum and reversal returns correspond to spreads in the slopes of the endogenous information. The empirical findings support the view that various classes of firms react differently to volatility risk, and endogenous information harbor important sources of potential risk loadings. Taken together, our results suggest that returns are influenced by random endogenous information flow, which is asymmetric in nature, and can be used as a performance attribution factor. If one fails to incorporate the existing asymmetric endogenous information hidden in the historical behavior, any attempt to explore average stock return predictability will be subject to an unquantified specification bias.Neste artigo, oferecemos um novo tipo de caracterização do risco da previsibilidade de dois conhecidos padrões anormais dos retornos médios das ações: momento e reversões. O objetivo é ilustrar a importância relativa dos fatores comuns de risco e da informação endógena para explicar a variabilidade no tempo dos retornos de momento e reversão. Nossos resultados demonstram que, mesmo na presença de carteiras de investimento nulo, os spreads dos retornos médios de momento e reversão correspondem aos spreads dos coeficientes angulares da informação endógena. Os resultados empíricos corroboram a perspectiva de que várias classes de empresas reagem de forma diferente ao risco de volatilidade e, tanto o tamanho quanto a relação valor patrimonial - valor de mercado da ação médios das empresas, contém, em conjunto, importantes fontes de risco potencial. Tomados em conjunto, nossos resultados sugerem que os retornos são influenciados pelo fluxo endógeno de informações aleatórias, que é assimétrico por natureza e que pode ser usado como fator de atribuição de desempenho. Quando não se incorporam as informações endógenas assimétricas existentes, escondidas no comportamento histórico, qualquer tentativa de explorar a previsibilidade da média do retorno das ações estará sujeita a um viés de especificação não quantificado