360 research outputs found

    A Primer on Islamic Finance: Definitions, Sources, Principles and Methods

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    Islamic finance is one of the most rapidly growing segments of the global financial system. However, despite the increasing importance of Islamic finance, particularly in developing economies in the Middle East and South-East Asia, religious and social complexity has acted against a fuller understanding by regulators, policymakers, researchers and practitioners. This paper provides a succinct and accessible analysis of the definition, sources, principles and methods of Islamic finance. This serves as a suitable starting point for further work into Islamic finance and many of the pressing regulatory, supervisory and competitive issues that remain as yet unaddressed

    An Empirical Survey of Individual Consumer, Business Firm and Financial Institution Attitudes towards Islamic Methods

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    Islamic finance – financial institutions, products and services designed to comply with the central tenets of Sharia (Islamic law) – is one of the most rapidly growing segments in global financial services. However, despite its growing importance, it is only relatively recently that attempts have been made to evaluate the attitudes, perceptions and knowledge of current and potential consumers and providers of Islamic financial products and services. This article provides a synoptic survey of the comparatively few empirical analyses of attitudes, perceptions and knowledge of Islamic finance. Individual consumer, business firm and financial institution attitudes to Islamic finance are examined and briefly compared with the larger body of extant work on attitudes, perceptions and knowledge of conventional financial services and products

    Temporada reproductiva y densidad poblacional en tres especies de aves de la familia Thamnophilidae del bosque seco tropical en el departamento del Tolima

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    58 P?ginasRecurso Electr?nicoLas especies Thamnophilus doliatus, Formicivora grisea y Myrmeciza longipes han sido registradas en el departamento del Tolima, asociadas a vegetaci?n en regeneraci?n, bosques secundarios y bordes de bosque en la zona de vida Bosque Seco Tropical (bs-T). Sin embargo, existe un vac?o de informaci?n en los periodos reproductivos y la estimaci?n demogr?fica en la regi?n. El objetivo de este estudio fue establecer la temporalidad reproductiva y la densidad poblacional de estas especies en el bs-T. Fueron consultadas las bases de datos del Programa de Monitoreo de Aves en Armero-Guayabal del periodo 2010-2013, registrando los estados reproductivos, comparando la fecha de los datos con las precipitaciones para determinar la temporalidad reproductiva. Se llevaron a cabo transectos en tres localidades (Armero-Guayabal, Potrerillo y Chaco) para estimar la densidad poblacional y relacionarlo con diferentes componentes del paisaje. Se encontr? mayor abundancia de individuos reproductivos de T. doliatus y F. grisea en abril-marzo (lluvias). La densidad global promedio de T. doliatus (0,53 Ind/Ha) fue mayor a M. longipes (0,23 Ind/Ha); en lluvias se present? densidades altas para T. doliatus en Armero-Guayabal (0,783 Ind/Ha) y Chaco (0,261 Ind/Ha), sequ?a para M. longipes en Armero-Guayabal (0,319 Ind/Ha); no se hall? relaci?n con los elementos del paisaje y la densidad. En conclusi?n, los picos reproductivos de T. doliatus y F. grisea se asociaron con las precipitaciones. La especie T. doliatus registr? la mayor densidad promedio global, encontrando que la densidad de T. doliatus y M. longipes vari? en diferentes ?pocas clim?ticas en los tres sitios de estudio.ABSTRACT. Thamnophilus doliatus, Formicivora grisea and Myrmeciza longipes species have been recorded in the department of Tolima, associated with regenerating vegetation, secondary forests and forest edges in the life zone Tropical Dry Forest life (bs-T). However, there is an information gap about reproductive periods and population estimates in the region. The aim of this study was to establish the reproductive seasonality and population density of these species in the bs-T. Databases were consulted of Bird Monitoring Program in Armero-Guayabal period 2010-2013, recording the reproductive stages, comparing rainfall data to determine reproductive seasonality. Transects were conducted at three locations (Armero-Guayabal, Potrerillo and Chaco) to estimate the population density and relate different components of the landscape. Greater abundance of reproductive individuals of T. doliatus and F. grisea in March-April (rains) was found. The average overall density of T. doliatus (0.53 Ind/ha) was higher than M. longipes (0.23 Ind/ha); rains for high densities in T. doliatus in Armero-Guayabal (0.783 Ind/ha) and Chaco (0.261 Ind/ha), drought in M. longipes Armero-Guayabal (0.319 Ind/ha) was presented; not related to landscape elements and the density was found. In conclusion, reproductive peaks T. doliatus and F. grisea associated with precipitation. T. doliatus species the highest total average density, find the density of T. doliatus and M. longipes varied in different climatic seasons in the three study sites.INTRODUCCI?N 13 1. OBJETIVOS 15 1.1 OBJETIVO GENERAL 15 1.2 OBJETIVOS ESPEC?FICOS 15 2. MARCO TEORICO 16 2.1 MARCO REFERENCIAL 16 2.1.1 Estrategias de vida y reproducci?n de aves Neotropicales 16 2.1.2 Densidad poblacional en aves 17 2.1.3 Especies focales del estudio 18 2.2 ANTECEDENTES 20 2.2.1 Thamnophilus doliatus (Linnaeus, 1764) 22 2.2.2 Myrmeciza longipes (Swainson, 1825) 22 2.2.3 Formicivora grisea (Boddaert, 1783) 23 3. METODOLOG?A 24 3.1 ?REA DE ESTUDIO 24 3.1.1 Localizaci?n geogr?fica 24 3.1.2 Sitios de muestreo 24 3.1.3 Variable ambiental 27 3.2 FASE DE CAMPO 28 3.2.1 Estado reproductivo 28 3.2.2 Densidad poblacional 29 3.3 ANALISIS DE DATOS 31 3.3.1 Temporada reproductiva 31 3.3.2 Densidad poblacional 31 3.3.3 An?lisis de paisaje 32 4. RESULTADOS 34 4.1 TEMPORADA REPRODUCTIVA 34 4.2 DENSIDAD POBLACIONAL 36 5. DISCUSI?N 41 5.1 TEMPORADA REPRODUCTIVA 41 5.2 DENSIDAD POBLACIONAL 42 5.3 CONSIDERACIONES FINALES 45 6. CONCLUSIONES 46 7. RECOMENDACIONES 47 REFERENCIAS 4

    Synthesis, cellular uptake and HIV-1 Tat-dependent trans-activation inhibition activity of oligonucleotide analogues disulphide-conjugated to cell-penetrating peptides

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    Oligonucleotides composed of 2′-O-methyl and locked nucleic acid residues complementary to HIV-1 trans-activation responsive element TAR block Tat-dependent trans-activation in a HeLa cell assay when delivered by cationic lipids. We describe an improved procedure for synthesis and purification under highly denaturing conditions of 5′-disulphide-linked conjugates of 3′-fluorescein labelled oligonucleotides with a range of cell-penetrating peptides and investigate their abilities to enter HeLa cells and block trans-activation. Free uptake of 12mer OMe/LNA oligonucleotide conjugates to Tat (48–58), Penetratin and R(9)F(2) was observed in cytosolic compartments of HeLa cells. Uptake of the Tat conjugate was enhanced by N-terminal addition of four Lys or Arg residues or a second Tat peptide. None of the conjugates entered the nucleus or inhibited trans-activation when freely delivered, but inhibition was obtained in the presence of cationic lipids. Nuclear exclusion was seen for free delivery of Tat (48–58), Penetratin and R(9) conjugates of 16mer phosphorothioate OMe oligonucleotide. Uptake into human fibroblast cytosolic compartments was seen for Tat, Penetratin, R(9)F(2) and Transportan conjugates. Large enhancements of HeLa cell uptake into cytosolic compartments were seen when free Tat peptide was added to Tat conjugate of 12mer OMe/LNA oligonucleotide or Penetratin peptide to Penetratin conjugate of the same oligonucleotide

    Cell-penetrating peptide conjugates of peptide nucleic acids (PNA) as inhibitors of HIV-1 Tat-dependent trans-activation in cells

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    The trans-activation response (TAR) RNA stem–loop that occurs at the 5′ end of HIV RNA transcripts is an important antiviral target and is the site of interaction of the HIV-1 Tat protein together with host cellular factors. Oligonucleotides and their analogues targeted to TAR are potential antiviral candidates. We have investigated a range of cell penetrating peptide (CPP) conjugates of a 16mer peptide nucleic acid (PNA) analogue targeted to the apical stem–loop of TAR and show that disulfide-linked PNA conjugates of two types of CPP (Transportan or a novel chimeric peptide R(6)-Penetratin) exhibit dose-dependent inhibition of Tat-dependent trans-activation in a HeLa cell assay when incubated for 24 h. Activity is reached within 6 h if the lysosomotropic reagent chloroquine is co-administered. Fluorescein-labelled stably-linked conjugates of Tat, Transportan or Transportan TP10 with PNA were inactive when delivered alone, but attained trans-activation inhibition in the presence of chloroquine. Confocal microscopy showed that such fluorescently labelled CPP–PNA conjugates were sequestered in endosomal or membrane-bound compartments of HeLa cells, which varied in appearance depending on the CPP type. Co-administration of chloroquine was seen in some cases to release fluorescence from such compartments into the nucleus, but with different patterns depending on the CPP. The results show that CPP–PNA conjugates of different types can inhibit Tat-dependent trans-activation in HeLa cells and have potential for development as antiviral agents. Endosomal or membrane release is a major factor limiting nuclear delivery and trans-activation inhibition

    A bi-functional siRNA construct induces RNA interference and also primes PCR amplification for its own quantification

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    RNA interference (RNAi) is a process of post-transcriptional gene silencing initiated by double-stranded RNAs, including short interfering RNA (siRNA). Silencing is sequence-specific and RNAi has rapidly become central to the study of gene function. RNAi also carries promise for selective silencing of viral and endogenous genes causal for disease. To detect the very low levels of siRNA effective for RNAi we modified the 3′ end of the sense strand of siRNA with a nuclease-resistant DNA hairpin. We show that the modified siRNA-DNA construct (termed ‘crook’ siRNA) functions as a primer for the PCR and describe a novel, yet simple PCR protocol for its quantification (amolar levels/cell). When transfected into mammalian cells, crook siRNA induces selective mRNA knock-down equivalent to its unmodified siRNA counterpart. This new bifunctional siRNA construct will enable future in vivo studies on the uptake, distribution and pharmacokinetics of siRNA, and is particularly important for the development of siRNA-based therapeutics. More generally, PCR-based detection of siRNA carries wide-ranging applications for RNAi reverse genetics

    Parallel synthesis and splicing redirection activity of cell-penetrating peptide conjugate libraries of a PNA cargo

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    A novel method for the parallel synthesis of peptide-biocargo conjugates was developed that utilizes affinity purification for fast isolation of the conjugates in order to avoid time consuming HPLC purification. The methodology was applied to create two libraries of cell-penetrating peptide (CPP)-PNA705 conjugates from parallel-synthesized peptide libraries. The conjugates were tested for their ability to induce splicing redirection in HeLa pLuc705 cells. The results demonstrate how the novel methodology can be applied for screening purposes in order to find suitable CPP-biocargo combinations and further optimization of CPPs.</p

    Systematic screening of LNA/2′-O-methyl chimeric derivatives of a TAR RNA aptamer

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    AbstractWe synthesized and evaluated by surface plasmon resonance 64 LNA/2′-O-methyl sequences corresponding to all possible combinations of such residues in a kissing aptamer loop complementary to the 6-nt loop of the TAR element of HIV-1. Three combinations of LNA/2′-O-methyl nucleoside analogues where one or two LNA units are located on the 3′ side of the aptamer loop display an affinity for TAR below 1nM, i.e. one order of magnitude higher than the parent RNA aptamer. One of these combinations inhibits the TAR-dependent luciferase expression in a cell assay
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