488 research outputs found
Evaluating the performance of managed funds: The cases of equity, ethical funds and Islamic index
Managed funds have become a popular investment tool and possess a lot of advantages. However, in spite of their popularity, most past research findings on the evaluation of performance have suggested that managed funds were unable to do significantly better than a large unmanaged portfolio. The aim of this thesis is to evaluate empirically the performance of managed funds. The funds chosen are; UK equity, ethical unit trusts and US-based Dow Jones Islamic index -an index of Islamic ethical funds portfolio. We examine the performance of UK equity unit trusts which invest in UK equities, using monthly samples over the 1986 to 2001 time period. The study compares the return of these unit trusts with a three-factor model which takes into account their exposure to market, value and size risk. After controlling the risk factors, it is found that manager’s under-perfom the market. Contrary to the notion that small company shares offer abundant "beat the market" opportunities, we find that small company trusts are the worst performers. The performance persistence of unit trusts is also examined and it is found that good performance does not persist. There are investors who out of their concern regarding adverse changes in our environment, concerns for justice, and because of their opposition to the arms race, decline to purchase the securities of such enterprises that engage in what are termed unethical or socially irresponsible activities. Such activities usually include, but are not necessarily limited to, the production of armaments, alcohol and tobacco; engaging in activities that degrade the environment; and engaging in activities that treat people unfairly. Declining to invest in the securities of enterprises that engage in unethical practices is not only a form of social protest, but can also have the effect of diminishing the demand for a company's securities. A diminishment of demand may then have an adverse financial impact on a company. This may prove to be a crucial factor in influencing companies to change and become more socially responsible. The question therefore arises: has the investment performance o f ethical investors suffered in comparison to those who are not so responsible? To answer the above, a study has been done which encompasses 35 U K ethical unit trusts which cover the period of seven years tough 1996. The study presents a comprehensive evaluation o f managed funds performance by employing various single to multifactor benchmark models.The added value of introducing extra variables such as size, book to market, momentum and a bond index is explored by evaluating the performance using conditional information and comparing the investment performance of U K ethical unit trusts with unit trusts which are not ethical. After controlling for style tilts and allowing for time variation in betas and expected return, the results show that there is no significant difference in performance between U K ethical unit trust and their conventional peers. Within an unconditional setting SMB, HML and momentum factors are best able to explain ethical unit trust returns. Therefore, unconditional models perform much better than their conditional peers. Islamic ethical investors apply both Islamic ethical and financial criteria when evaluating investments in order to ensure that the securities selected are consistent with their value system and beliefs. Using monthly returns for the period starting from January 1996 to December 2003, the study is conducted to see the potential impact that Islamic ethical restrictions may have on investment performance by comparing the performance characteristics o f a diversified portfolio of Islamic screened stocks (Dow Jones Islamic index) w i t h conventional benchmark portfolio ( Dow Jones Index- Americas). Contrary to expectations, our findings indicate that application of Islamic ethical screens do not necessarily have an adverse impact on investment performance. Results actually show that expected returns of Islamic screened portfolios are higher than the expected returns o f conventional portfolios
Market Efficiency, Time-Varying Volatility and Equity Returns in Bangladesh Stock Market
This paper empirically examines the issue of market efficiency and time-varying risk return relationship for Bangladesh, an emerging equity market in South Asia. The study utilizes a unique data set of daily stock prices and returns compiled by the authors which was not utilized in any previous study. The Dhaka Stock Exchange (DSE) equity returns show positive skewness, excess kurtosis and deviation from normality. The returns display significant serial correlation, implying stock market inefficiency. The results also show a significant relationship between conditional volatility and the stock returns, but the risk-return parameter is negative and statistically significant. While this result is not consistent with the portfolio theory, it is possible theoretically in emerging markets as investors may not demand higher risk premia if they are better able to bear risk at times of particular volatility (Glosten, Jagannathan and Runkle, 1993). While circuit breaker overall did not have any impact on stock volatility, the imposition of the lock-in period has contributed to the price discovery mechanism by reverting an overall negative riskreturn time-varying relationship into a positive one. As a policy to improve the capital market efficiency, the timely disclosure and dissemination of information to the shareholders and investors on the performance of listed companies should be emphasized.
Sustainable Development and Islamic Ethical Tasks for Business-Organisations
The paper seeks to addresses the issues of sustainable development and it would be viewed as Islamic moral duties for business. To what level should business bodies should join in the sustainable development activities? Based on the existing literature, this study assimilates conventional as well as Islamic points about environment and sustainable development and contends that whatever explanation of sustainable development one may subscribe, ultimately, each should culminate in environmental concern. This study contends that Islamic style is more friendly to environmental protection and issues touching sustainable development have moral, social and ethical responsibility. With intense commitment of the businesses in the matter of Islamic ethics to equity, justice and wellbeing of humans, it demands that business organisations in the Islamic and other countries should participate in the sustainable development endeavours. Because of ethics of environmental aspects in Islam, the value chains of suppliers through customers, many companies may be alert for the environmental characteristics and effects of their businesses
Architectural Mimics of FeFe-Hydrogenase H-Cluster: Synthesis, Characterization and Electrochemical studies
The utilization of H2 for energy was probably a crucial feature of very early life on this planet. Therefore, the tendency to find a proper way to produce H2 is an interest area for research in the scientific community. In Fact, the nature has high ability to catalyze the reversible reduction of protons to molecular hydrogen through metalloenzymes known as hydrogenases. These metalloenzymes can be classified into [Fe]-hydrogenases (Hmd), [NiFe]-hydrogenases and [FeFe]-hydrogenases. In the case of the latter, the reaction takes place at the “H-cluster”, which consists of an [4Fe4S] cubane attached through a cysteinyl residue to a butterfly [2Fe2S] sub-cluster. The [2Fe2S] unit features a bridging azadithiolato ligand as well as biologically unusual CO and CN- ligands. Over the past decades, numerous synthetic models which mimic the H-cluster have been reported to provide a better understanding of the structure and function of the active site of the enzyme-mimic models. Moreover, these models have been extended to diiron complexes containing diselenato and ditellurato ligands
Western Civilization in View of Sheikh Muhammad Wadeh Al-Rasheed Al-Hasani Al-Nadawi
الحضارة الغربية التي في الحقيقة حضارة استغلال، وازدواجية، وهي مجردة عن القيم الإنسانية، وواقعها الاستعمار، والتبشير، والتحريف، والتزوير. والفكر الغربي الذي نشأ في أحضان وثنية اليونان وعبادة القيصر الإله الروماني، ثم اصطبغ ميراثه هذا بأساطير اليهودية المحرفة ومفاهيم المسيحية التي انصهرت في بوتقة أديان التثليث، أصبح اليوم فكرا عالميا، ويحاول أن يفرض نفوذه على جميع الناس عامة وعلى الأمة الإسلامية خاصة. فلا بد للأمة الإسلامية أن تدرس اليوم دراسة مقارنة بين الحضارة العربية الإسلامية والحضارة الأوربية وتعرف حقائق الحضارتين وتحدد موقفها من الحضارة الغربية والفكر الغربي ولا تبعد عن روح العربية والخصال الفطرية. فوفق الله تعالى في الأمة الإسلامية رجالا غير واحد ليقوموا بهذه المسؤولية، فهاجموا الحضارة الغربية والفكر الغربي، وكشفوا زيفها ودعوا الناس إلى مقاومتها وحماية نفوسهم من الانصهار فيها. وأستاذنا الشيخ محمد واضح الرشيد الحسني الندوي رحمه الله تعالى (1935-2019م.) ينتمي إلى هؤلآء الرجال. فهو الذي قام بتحليل الفكر الغربي، وفلسفته المادية تحليلا علميا موضوعيا دقيقا، و أثبت بالدلائل والبراهين أنها حضارة الاستغلال، والثنوية والازدواجية، والشعور الإنساني مفقود في هذه الحضارة. وصدرت له في هذا المجال مقالات في جريدة ’الرائد‘، ومجلة ’البعث الإسلامي‘. وقام المجمع الإسلامي العلمي بلكناؤ بجمع بعض هذه المقالات وطبعها في صورة كتاب عام 2012م. تحت عنوان ’إلى نظام عالمي جديد‘. وهذا الكتاب يشتمل على بابين هامين بالإضافة إلى تقديم الكتاب بقلم فضيلة الشيخ محمد الرابع الحسني الندوي، وكلمة تعريف وتقديم للأستاذ نذر الحفيظ الندوي، وكلمة بين يدي الكتاب وتمهيد بقلم المؤلف، وفهرس الكتاب.Western civilization as described by many scholars is a civilization accused of exploitation and duplicity. The reality is colonialism, distortion, and forgery. Western thought, which originated in the hands of Pagan Greece and the worship of the Roman God Caesar, then tainted its legacy with the distorted myths of Judaism and the concepts of Christianity. Today, it has become a global thought, and it is trying to impose its influence on all the people in general and on the Islamic nation in particular. Thus, the Islamic nation should have done today a comparative study between the Arab-Islamic civilization and the European civilization and try to know the realities of the two civilizations and determine its position on Western civilization and Western thought, and not be far from the Arab spirit and innate characteristics.
Allah the Almighty blessed the Islamic nation with many jealous Islamic scholars to carry out this responsibility, so they criticized Western civilization and thought, exposed its falsity, and called on people to resist it and protect their souls from assimilating into it. The prominent Islamic scholar, Sheikh Muhammad Wadeh Al-Rashid Al-Hasani Al-Nadawi(1935-2019 AD.) belongs to this group. He analysed Western thought and its materialistic philosophy in a scientific way and proved with evidence that it is a civilization of exploitation and dualism, and human feeling is missing in this civilization. He published articles in this field in Al-Raid newspaper and Al-Baath Al-Islami magazine (both are published in Darul Uloom Nadwatul Ulama, Luknow). The Islamic Scientific Academy in Lucknow collected some of these articles and printed them as a book in 2012 AD. entitled 'To a New World Order'. In this article, humble efforts have been made to study the book and analyse it to understand the facts raised by Sheikh Muhammad Wadeh Al-Rashid Al-Hasani Al-Nadawi in an objective manner
Incorporating Chromatin Accessibility Data into Sequence-to-Expression Modeling
AbstractPrediction of gene expression levels from regulatory sequences is one of the major challenges of genomic biology today. A particularly promising approach to this problem is that taken by thermodynamics-based models that interpret an enhancer sequence in a given cellular context specified by transcription factor concentration levels and predict precise expression levels driven by that enhancer. Such models have so far not accounted for the effect of chromatin accessibility on interactions between transcription factor and DNA and consequently on gene-expression levels. Here, we extend a thermodynamics-based model of gene expression, called GEMSTAT (Gene Expression Modeling Based on Statistical Thermodynamics), to incorporate chromatin accessibility data and quantify its effect on accuracy of expression prediction. In the new model, called GEMSTAT-A, accessibility at a binding site is assumed to affect the transcription factor’s binding strength at the site, whereas all other aspects are identical to the GEMSTAT model. We show that this modification results in significantly better fits in a data set of over 30 enhancers regulating spatial expression patterns in the blastoderm-stage Drosophila embryo. It is important to note that the improved fits result not from an overall elevated accessibility in active enhancers but from the variation of accessibility levels within an enhancer. With whole-genome DNA accessibility measurements becoming increasingly popular, our work demonstrates how such data may be useful for sequence-to-expression models. It also calls for future advances in modeling accessibility levels from sequence and the transregulatory context, so as to predict accurately the effect of cis and trans perturbations on gene expression
Computational modeling of gene expression from regulatory sequences
Regulation of gene expression is an important early step in controlling every biological process that underlies the function of living organisms. Even though gene expression may be regulated in several stages, the modulation occurs mostly at the primary stage known as “transcription”. Teasing out the details of transcriptional regulation is therefore a core focus of biological research. Transcriptional regulation of gene expression is dictated by regulatory DNA sequences, often called cis-regulatory modules (CRM; also known as “enhancer”), that contain specific binding sites for regulatory proteins (transcription factors, TF). The assembly of TFs bound on a CRM drives the desired expression level of the gene associated with the CRM. As the abundance of TFs vary across different cell types, the expression level of the gene, also termed as the “readout” of the CRM, varies accordingly and results in the aforementioned control over biological processes. The rules, collectively known as the “cis-regulatory logic”, to predict gene expression level given information about CRMs and TFs, however, are unclear. Decades of experimental studies have hypothesized mechanisms about parts of this regulatory process (e.g., about the influence of TF-TF interactions), but a comprehensive study of cis-regulatory logic is feasible only through computational models. The subject of this thesis is to develop mechanistic models of gene expression from regulatory sequences and use the models to understand such details of the system that are difficult to assess experimentally.
The first part of this thesis develops a model that integrates the regulatory effect of signaling pathways with that of sequence-bound TFs to understand the expression pattern of a gene from its CRM. Given the various types of molecular interactions that the model needs to capture, it is both complex in structure and rich in the number of parameters. Similarly complex models commonly used in other disciplines, from signaling networks to climatology, have been shown to fit many distinct parameterizations that are equally consistent with data but might represent disparate mechanistic hypotheses. Whether this is also the case for models of cis-regulation has never been investigated, with the standard practice in this realm being to report a single or a few best-fit models. We demonstrate here – taking the Drosophila ind gene as an example – that gene expression modeling from cis-regulatory sequences may suffer from incomplete and even incorrect conclusions if one adheres to this current practice. We construct an ensemble of models by systematically exploring the entire parameter space and leveraging both wild-type data and various perturbation experiments, and make statistical inferences from the ensemble about detail regulatory mechanisms of ind. Years of genetic experiments have put forth an assortment of hypotheses about ind regulation. We use our modeling approach to show how a mechanism involving MAPK induced attenuation in the DNA binding affinity of Capicua and the use of low-affinity Dorsal binding sites may provide a coherent explanation of ind regulation. Also, we quantitatively predict and experimentally validate the role of the “pioneer factor” Zelda in activating ind. Finally, we discuss disparate hypotheses that are supported by our ensemble of models and will need future experimentation for a complete understanding of ind regulation.
The second part of this thesis addresses a fundamental goal of computational biology, namely that of modeling a gene’s expression from its intergenic locus and trans-regulatory context. Owing to the distributed nature of cis-regulatory information and the poorly understood mechanisms that integrate such information, gene locus modeling is a more challenging task than modeling individual enhancers. Here we report the first quantitative model of a gene’s expression pattern as a function of its locus. We model the expression readout of a locus in two tiers: 1) combinatorial regulation by transcription factors bound to each enhancer is predicted by a thermodynamics-based model and 2) independent contributions from multiple enhancers are linearly combined to fit the gene expression pattern. The model does not require any prior knowledge about enhancers contributing toward a gene’s expression. We demonstrate that the model captures the complex multi-domain expression patterns of anterior-posterior patterning genes in the early Drosophila embryo. Altogether, we model the expression patterns of 27 genes; these include several gap genes, pair-rule genes, and anterior, posterior, trunk, and terminal genes. We find that the model-selected enhancers for each gene overlap strongly with its experimentally characterized enhancers. Our findings also suggest the presence of sequence-segments in the locus that would contribute ectopic expression patterns and hence were “shut down” by the model. We applied our model to identify the transcription factors responsible for forming the stripe boundaries of the studied genes. The resulting network of regulatory interactions exhibits a high level of agreement with known regulatory influences on the target genes. Finally, we analyzed whether and why our assumption of enhancer independence was necessary for the genes we studied. We found a deterioration of expression when binding sites in one enhancer were allowed to influence the readout of another enhancer. Thus, interference between enhancer activities was a possible factor necessitating enhancer independence in our model.
The third part of this thesis applies the aforementioned models to two novel datasets. The first dataset was created by fusing two well-studied CRMs of the even-skipped (eve) gene in Drosophila. The fused constructs differ in the way the CRMs’ orientation, order, and intervening spacing are varied. Interestingly, the two constituent CRMs regulate eve expression by using the same TFs, although binding affinities (i.e., strength) of the repressor sites in the two CRMs are different – an observation that has been implicated to help the CRMs drive expression in two distinct domains (each domain consists of two stripes of eve) when they act in their endogenous context. However, the fact that these two CRMs harbor sites for the same TFs makes it difficult to predict the readouts of the constructs in our dataset. In particular, readouts of these constructs show some subtle aspects that essentially challenge the conventional models of information integration from sequences and suggest that a different mechanism may be necessary to explain these observations. Our modeling of this novel dataset suggests that the conventional assumption that relatively short DNA sequences, e.g., CRMs, do not comprise smaller “independent” regulatory sequences may not be true – since the lengths of the fused constructs are comparable to typical CRMs and their readouts can be modeled by assuming the existence of smaller independent regulatory segments. The second dataset modeled in this part of the thesis features five genes that control the growth and patterning of wing in Drosophila. Notably, ours is the first attempt to link regulatory sequences and the related molecular details to the growth and scaling of an organ. In course of fitting this dataset, we identify the important regulatory role of a TF called Scalloped (Sd) and speculate on Sd’s role in assuring that the expression domains of the studied genes scale with wing growth. We also use our models to identify novel regulatory sequences of these genes and to answer several questions that were left open in the experimental studies that attempted first to understand the cis-regulatory logic for these genes
An Analysis of Returns and Volatility Spillovers and their Determinants in Emerging Asian and Middle Eastern Countries
This study investigates the return spillovers and volatility spillovers from developed markets (e.g., Europe, Japan and the US) into the financial markets of selected emerging countries in Asia and the Middle East and North Africa (MENA) region. Based on constant and trend spillover models, we find evidence of significant spillover effects from developed markets to emerging markets. The results from variance ratios indicate the dominance of US shocks across all emerging markets, though the effect varies widely among countries. New to these literature, we conduct an empirical analysis quantifying the underlying determinants affecting the extent of shock spillovers. The results show that bilateral factors such as trade volume, portfolio investment and distance are significant in explaining the spillover effects
Antioxidant, antimicrobial and cytotoxic activities of Corypha taliera Roxb
The methanol extract of Corypha taliera fruits as well as its n-hexane, carbon tetrachloride,
dichloromethane and aqueous soluble fractions were subjected to screening for antioxidant, antimicrobial
and cytotoxic activities. The methanolic crude extract exhibited the highest antioxidant activity (IC50 19.33
μg/ml as compared to 9.5 μg/ml for the standard agent, BHT). The crude methanol extract and its carbon
tetrachloride, dichloromethane and aqueous soluble fractions showed mild to moderate inhibition of microbial
growth against some of the tested organisms. All the extractives exhibited strong cytotoxic properties,
among which the methanol extract revealed the strongest cytotixicity (LC50 = 0.43 μg/ml).Colegio de Farmacéuticos de la Provincia de Buenos Aire
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