An analysis of skewness and skewness persistence in three emerging markets

This paper reports an investigation into the extent and persistence of skewness in stock returns in three emerging markets, namely the Czech Republic, Kenya and Poland. The study is undertaken using the extended skew normal distribution and an asymmetric version of the generalised error distribution. The motivation for this paper is the hypothesis that skewness is a particular feature of returns in emerging markets; it may lack persistence and may decline in absolute terms as time passes and the market matures. When daily returns are considered, the majority of stocks in all three markets exhibit a significant degree of skewness. The value of the skewness parameter is often different in each of the three estimation periods considered. Little evidence has been found to support the view that skewness is an artifact of emerging or evolving markets. Over the period covered by the study, the number of stocks with a significant degree of skewness has remained more or less the same. For weekly returns, the same conclusions apply to the Czech Republic and to Kenya, but there is far less evidence of skewness in weekly returns on Polish Stocks. There is consistent evidence of short-term reversion in daily returns; increases (decreases) in mean return and volatility imply that there will be a decrease (increase) in skewness in the next month. This effect does not persist over longer time horizons

An analysis of skewness and skewness persistence in three emerging markets

This paper reports an investigation into the extent and persistence of skewness in stock returns in three emerging markets, namely the Czech Republic, Kenya and Poland. The study is undertaken using the extended skew normal distribution and an asymmetric version of the generalised error distribution. The motivation for this paper is the hypothesis that skewness is a particular feature of returns in emerging markets; it may lack persistence and may decline in absolute terms as time passes and the market matures. When daily returns are considered, the majority of stocks in all three markets exhibit a significant degree of skewness. The value of the skewness parameter is often different in each of the three estimation periods considered. Little evidence has been found to support the view that skewness is an artifact of emerging or evolving markets. Over the period covered by the study, the number of stocks with a significant degree of skewness has remained more or less the same. For weekly returns, the same conclusions apply to the Czech Republic and to Kenya, but there is far less evidence of skewness in weekly returns on Polish Stocks. There is consistent evidence of short-term reversion in daily returns; increases (decreases) in mean return and volatility imply that there will be a decrease (increase) in skewness in the next month. This effect does not persist over longer time horizons

The biological impacts of urban runoff waters

INTRODUCTION. My work with the Middlesex University Urban Pollution Research Centre has been conducted in the following areas: 1 Biological Monitoring of Urban Waters (Publications 1, 3, 5, 6, 25) Conventional biological methods and hydrobiological indices used for assessing water quality have been tested in urban streams and rivers and their limitations exposed. The impact of river engineering and physical disturbance on the substrate during storm events has been shown to influence significantly the index scores in addition to pollution impacts. The recommendation to compare biological with physico-chemical assessment of water quality has also been adopted by the National Rivers Authority. A model to predict the community diversity index score for urban stream macro invertebrate biota from recorded physico-chemical parameters was satisfactory for fairly clean waters and for moderate levels of pollution but not for serious levels of pollution (1). Reference streams and ponds in Trent Country Park on the fringe of North London were used for comparison with studies of the biota of urban waters (3,5). A system of river classification using a hydrobiological score system was proposed to complement the existing National Water Council system which was essentially based on chemical criteria (6). A study of the use of indicator organisms to monitor the impact of localised discharges of urban surface runoff and storm sewer overflows was commissioned by the Water Research Centre, the results of which are reported in paper no. 14. A review of the use of macroinvertebrates and plants as bioindicators in urban aquatic systems is included in publication 25. 2 Aquatic Ecotoxicology (Publications 3, 4, 5, 6, 7, 9, 11, 12, 14, 21, 24, 26, 28, 32, 34) 2.1 Heavy Metals Innovative methods have been developed for assessing heavy metal bioaccumulation in selected macro invertebrate species in urban waters. Traditionally, toxicity tests have been conducted in controlled laboratory conditions which do not simulate the natural environment. The use of caged macro invertebrates secured to the substrate in rivers, enables a more realistic determination of bioaccumulation and mortality rates to be made. The impact of storm events and chronic exposure to contaminated water and sediment has been investigated. At a time when new ecotoxicological tests are being introduced to the UK and the EC, the research has considerable potential application as a test for heavy metal impacts and the determination of environmental standards in freshwater. (The research has been sponsored by the Water Research Centre). VI Tissue concentrations of lead, cadmium, copper and zinc in selected macroinvertebrates collected from semi-rural and urban streams and ponds are reported in papers 3, 4 and 5. The relationship between urbanisation and macro invertebrate tissue, sediment and water metal concentrations and their spatial trends along the Salmon's Brook in North London is discussed in publication 6 and compared with the results from the A veiro Lagoon and its feeding rivers in North Portugal in paper 7. Tissue metal bioaccumulation in popUlations of caged Gammarus pUlex, Asellus aquaticus and Lymnea peregra in relation to ambient sediment and water metal concentrations, metal species bioavailability and organism feeding behaviour are discussed in publication 9. A comparison of mortality and metal uptake in aquatic macroinvertebrate species in field studies and laboratory experiments and a recommendation to reduce the length and lethal limit of the traditional 96 hour LC50 test is made in papers 11, 21, 24 and 32. The impact of storm sewer overflows from a sewage treatment works on caged macro invertebrates exposed to the discharges and to the receiving waters immediately downstream is reported in publications 12, 14 and 24. Principal component analysis was used to determine combinations of caged Aselius aquaticus tissue, sediment and water metal concentrations, precipitation volumes and antecedent dry periods which explained much of the variation in organism mortality and weight (28, 34). 2.2 Hydrocarbons (Publications 15 - 20, 29) Caged macro invertebrate species have also been used to determine hydrocarbon bioaccumulation in an urban stream and the Welsh Harp reservoir, a site of special scientific interest. Sediment and water hydrocarbon concentrations and macro invertebrate community diversity have been monitored along the stream and in the reservoir to investigate the impact of an oil boom. The development of biological and chemical techniques in this unique study of an urban freshwater wetland has led to considerable interest and further publications are planned. (The research has been sponsored by English Nature, formerly the Nature Conservancy Council). Publications 15 and 16 describe a baseline study of the ecotoxicological impacts resulting from oil pollution on the Welsh Harp and one of its receiving streams. Sediment and water concentrations of alkanes and P AHs and the tissue concentrations and temporal and spatial trends in selected caged macro invertebrates and fish are reported in publications 17, 18 and 19. The bioaccumulation of hydrocarbons by macro invertebrate species in laboratory tests and the corresponding mortality rates and their comparison with the results of field studies and controlling factors are discussed in publication 20. The results of the study are summarised in paper 29. vii 3 Aquatic Macrophyte Pollution Control (Publications 10, 13, 22, 23, 27, 31, 33, 35) Heavy metal uptake by the reedmace Typha latifolia, an aquatic plant species, has been investigated in urban wetlands and in greenhouse based studies. The research has shown a high level of tolerance by Typha to heavy metals and its biofiltration ability and creation of a sediment metal sink. It has led to the introduction of Typha in pioneering designs of constructed wetlands for highway runoff treatment in the UK. (The research is ongoing and is receiving sponsorship from industry and PCFC). A comparison of the water pollution control performance of Typha latifolia in the UK and Eicchomia crassipes in China is discussed in publication 10. Further details of the study of metal uptake in Typha latifolia and its associated sediment in the Welsh Harp and two ornamental ponds and a comparison with the results of a greenhouse based metal dosing experiment are given in papers 13 and 27 and summarised in 23 and 31. An analysis of the metal and hydrocarbon uptake and biofiltration ability of different species of aquatic macrophyte in an experimental pond receiving runoff from a car park in Washington State, USA is described in report 33

Work-related conditionality and the access to social benefits of national citizens, EU and non-EU citizens

This article contributes to an understanding of how conditionality applies across social security and immigration policies in restricting the access to social benefits of national citizens, EU and non-EU citizens. Specifically, the article builds on Clasen and Clegg’s (2007) framework of conditionality in the context of welfare state reform by extending that conceptual framework to include migration. The framework is applied to examine how different levels of conditionality have been implemented in UK policy reforms to restrict access to rights of residence and to social benefits. It is argued that a conditionality approach moves beyond a binary of citizens and migrants in social policy analysis, contributing to an understanding of the dynamics and interactions of work-related conditions in restricting access to social benefits, with implications for inequalities that cut across national, EU and non-EU citizens in terms of the relationship of particular groups to the market

All EU migrants are not equal: the gendered consequences of Brexit

EU residency rights have gendered consequences, writes Isabel Shutes, Assistant Professor of Social Policy at the LSE. The unpaid labour of women with young children, who take time out of paid work to look after them, is not recognised as “genuine and effective work” in EU case law. Consequently, they are at greater risk of losing their status as ‘workers’ and have to rely on having a partner who is a working EU citizen or being self-sufficient to claim residence rights. Brexit negotiators must avoid putting an extra, gendered burden on these women to prove their right to stay

Labour Supply Curves for EU Member and Candidate States: An applied general equilibrium analysis. Factor Markets Working Paper No. 26, June 2012

This paper introduces a more sophisticated modelling of the labour market functioning of the European member and candidate states through the introduction of labour supply curves in an applied general equilibrium model. A labour supply curve offers a middle way in labour supply modelling, sitting between the two commonly adopted extremes of spare capacity and full employment. The first part of the paper outlines the theoretical foundation of the labour supply curve. Real world data is then used to derive labour supply curves for each member state, along with Croatia and Turkey. Finally, the impact of the newly specified labour markets on the results of an illustrative scenario involving reform of the common agricultural policy is explored. The results of computable general equilibrium analysis with the labour supply curve confirm the theoretical expectation that modelling the labour supply through an upwards-sloping curve produces results that lie between the extremes of spare capacity of the labour factor and fully employed labour. This specification captures a greater degree of heterogeneity in the labour markets of the member and candidate states, allowing for a more nuanced modelling of the effects of policy reform, including welfare effects

When unpaid childcare isn't 'work': EU residency rights have gendered consequences

All EU migrants are not equal when it comes to residency rights, writes Isabel Shutes, Assistant Professor of Social Policy at the LSE. The unpaid labour of women with young children, who take time out of paid work to look after them, is not recognised as “genuine and effective work” in EU case law. Consequently, they are at greater risk of losing their status as ‘workers’ and have to rely on having a partner who is a working EU citizen or being self- sufficient to claim residence rights. Brexit negotiators must avoid putting an extra, gendered burden on these women to prove their right to stay

Studies on the small G protein Rac1: Interaction with IQGAP and the role of Mg2+ during nucleotide exchange

This Thesis is centred around the small G-protein Rac1, and investigates: Rac's interaction with the effector protein IQGAP; the role of Mg2+ during Rac's nucleotide exchange; and Rac1's proposed self-stimulatory activity. Rac1's C-terminal tail has been suggested to posses GTPase self-stimulatory activity. An investigation of this property is described. The effects on Rac's intrinsic GTPase rate were observed using full-length and C-terminal truncated forms of the protein, as well as Raco GMPPNP forms and peptides of Rac's C-terminal tail. In contrast to the previously published data, no significant increase in rate was observed in the presence or absence of the C-terminal tail. The role of Mg2+ in nucleotide exchange is examined using both novel (MBC: 7- Monoethylamino 8-bromocoumarin) and well characterised (Mant: N-methylanthraniloy1) fluorophores, covalently bound to Rac-complexed nucleotides. Fluorescent intensity measurements suggest a two step model of release of Mg2+ and nucleotide from Raco nucleotide complexes during exchange. This model is supported by anisotropy data and use of Mg2+ as a substitute for Mg2+, which allows examination of each of the two steps separately. Further work examines the Mg2+ binding to Raco nucleotide complexes, and combined with the release data allows calculation of dissociation constants for Mg2+ from the Rac complexes. IQGAP has been suggested to associate with Rac1 and inhibit its intrinsic GTPase activity. These observations are confirmed in this report by measurements made on single turnover GTP hydrolysis of Rac in the presence or absence of IQGAP. The kinetics of this association are measured using fluorescent intensity and fluorescent anisotropy techniques. The use of a panel of Rac mutants provides a method to asses the importance of different Rac regions in the interaction with IQGAP. IQGAP exhibits a relatively high affinity with wild type Rac. The mutant studies suggest that the main contribution to association of Rac with IQGAP occurs via the Effector Region, with a small contribution from the Insert Loop

Ten Regulatory and Cultural Principles That Improve California\u27s Drought Planning

Forty-one of the past hundred years in California have been part of multi-year drought sequences. The 2012–2015 drought was one of the worst of the last hundred years, and there are increasing concerns that climate change will increase the frequency of drought in California. This article deals with ten regulatory and cultural principles developed in the last decade that are becoming embedded in drought planning in California