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We show that the use of correlations for modeling dependencies may lead to counterintuitive behavior of risk measures, such as Value-at-Risk (VaR) and Expected Short- fall (ES), when the risk of very rare events is assessed via Monte-Carlo techniques. The phenomenon is demonstrated for mixture models adapted from credit risk analysis as well as for common Poisson-shock models used in reliability theory. An obvious implication of this finding pertains to the analysis of operational risk. The alleged incentive suggested by the New Basel Capital Accord (Basel II), amely decreasing minimum capital requirements by allowing for less than perfect correlation, may not necessarily be attainable.
This paper investigates the value of observed river discharge data for global-scale hydrological modeling of a number of flow characteristics that are e.g. required for assessing water resources, flood risk and habitat alteration of aquatic ecosystems. An improved version of the WaterGAP Global Hydrology Model (WGHM) was tuned against measured discharge using either the 724-station dataset (V1) against which former model versions were tuned or an extended dataset (V2) of 1235 stations. WGHM is tuned by adjusting one model parameter (γ) that affects runoff generation from land areas in order to fit simulated and observed long-term average discharge at tuning stations. In basins where γ does not suffice to tune the model, two correction factors are applied successively: the areal correction factor corrects local runoff in a basin and the station correction factor adjusts discharge directly the gauge. Using station correction is unfavorable, as it makes discharge discontinuous at the gauge and inconsistent with runoff in the upstream basin. The study results are as follows. (1) Comparing V2 to V1, the global land area covered by tuning basins increases by 5% and the area where the model can be tuned by only adjusting γ increases by 8%. However, the area where a station correction factor (and not only an areal correction factor) has to be applied more than doubles. (2) The value of additional discharge information for representing the spatial distribution of long-term average discharge (and thus renewable water resources) with WGHM is high, particularly for river basins outside of the V1 tuning area and in regions where the refined dataset provides a significant subdivision of formerly extended tuning basins (average V2 basin size less than half the V1 basin size). If the additional discharge information were not used for tuning, simulated long-term average discharge would differ from the observed one by a factor of, on average, 1.8 in the formerly untuned basins and 1.3 in the subdivided basins. The benefits tend to be higher in semi-arid and snow-dominated regions where the model is less reliable than in humid areas and refined tuning compensates for uncertainties with regard to climate input data and for specific processes of the water cycle that cannot be represented yet by WGHM. Regarding other flow characteristics like low flow, inter-annual variability and seasonality, the deviation between simulated and observed values also decreases significantly, which, however, is mainly due to the better representation of average discharge but not of variability. (3) The choice of the optimal sub-basin size for tuning depends on the modeling purpose. While basins over 60 000 km2 are performing best, improvements in V2 model performance are strongest in small basins between 9000 and 20 000 km2, which is primarily related to a low level of V1 performance. Increasing the density of tuning stations provides a better spatial representation of discharge, but it also decreases model consistency, as almost half of the basins below 20 000 km2 require station correction.
Using molecular tools to differentiate closely related blackfly species of the genus Simulium
(2008)
Biodiversity data are the foundation for conservation and managemet and taxonomy provides the reference system, skills and tools used to identify organisms. Species level data such as species richness, composition and diversity are common metrics. However, species level identification of organisms tends to be neglected within ecological work, especially within monitoring programmes, but also in conservation biology (Giangrande, 2003). This is because collection of species level data is time consuming, with identification of species-specific characteristics traditionally involving lengthy examination of samples using microscopy. In addition it is costly and species level data is almost impossible to collect if the taxa involved are species rich and difficult to identify (Báldi 1999). Other reasons why species level identification is neglected include the fact that sample collection can damage organisms, so diagnostic morphological features are lost, or that individuals may be in a life history stage or of a sex that does not have diagnostic morphological characteristics. Furthermore, the numbers of available expert taxonomists needed for species identification are in decline and have been for several decades. Species identification using molecular taxonomy where DNA is used as a marker is championed as a tool for resolving a range of morphological problems, such as the association of all life history stages, correlating male and female specimens to the same species and identifying partial specimens. Traditional taxonomy is built around morphological variations between species, with systematic inferences based upon shared physical characters. In molecular taxonomy on the other hand, proteins and genes are used to determine evolutionary relationships. ’DNA barcoding’ aims to provide an efficient method for species-level identification and it is thought that it will provide a powerful tool for taxonomic and biodiversity research (Hajibabaei et al. 2007). Cited strengths of a molecular based approach to species identification include the potential universality and objective nature of DNA data as taxonomic information, the usefulness of molecular data in animal groups characterized by morphological cryptic characters and the use of DNA sequence information to determine otherwise ‘unidentifiable’ biological material (such as incomplete specimens or immature specimens). Its aim is to increase the speed, precision and efficiency of field studies involving diverse and difficult to identify taxa and it has the potential to be automated to provide a rapid and consistently accurate supplementary identification system to traditional taxonomy. This project was a proof-of-concept study that investigated the feasibility of using DNA barcodes to differentiate closely related blackfly species of the genus Simulium. The longer term objective would be to apply such molecular approaches to organisms used in water quality monitoring and to biodiversity studies to provide a quick, robust but practical and cost effective tool for species identification. Great Britain is currently home to 33 morphospecies of blackfly many of which are morphologically close to other species and have been the cause of much systematic revision. In addition to evaluating the use of DNA barcodes in species identification, a non-destructive DNA extraction method was developed to preserve voucher pecimens that will allow a complete morphological classification to be carried after DNA extraction. Using molecular tools to differentiate closely related blackfly species of the genus Simulium v Finding an effective DNA barcode for an individual species involves accurate taxonomic identification and the retention of voucher specimens for future morphological studies. A rapid non-destructive method for DNA extraction from small insects was developed where no clean-up step was required prior to amplification and it was possible to extract DNA of sufficient quality in minutes retaining diagnostic morphological characteristics. For any molecular tool used for species discrimination, an important consideration is defining the specific genetic loci (e.g. the position of genes on a chromosome) to be monitored. All blackfly species in this study were successfully amplified with the standard barcoding coxI gene primer pair LCO1490 5'-GGT CAA CAA ATC ATA AAG ATA TTG G-3' and HCO2198 5'-TAA ACT TCA GGG TGA CCA AAA AAT CA-3' (Folmer et al. 1994) and we did not need to optimise or redesign the primer sequence.
This book is about emerging informal responses to unemployment in Malawi. To the bicycle taxi and handcart operators who are at the centre of the book, informality is a means for negotiating newer experiences and challenges associated with urbanisation. Jimu richly documents how informal economy activities continue to represent grassroots responses to widespread poverty, unavailability of meaningful employment opportunities and the failure of the state as well as the private and the non-state sectors to respond to escalating demand for formal sector jobs. Multiplicity of activities and straddling urban and rural opportunities are strategies employed to deal with opportunity impermanence and maximize returns from various low paying tasks and jobs. While these activities have grown without state support, state involvement is necessary to regulate and promote the welfare of the workers in the sector as well as that of the users of their service and the general public. This will require constructive engagement among the operators, users of their services, local government, and various state agencies.
This book explores the latent and sometimes overt undercurrents that have shaped the judicial history of Cameroon since the United Nations Trusteeship period. It is an insightful account by a critical observer privileged to serve as Director of Public Prosecutions and a judge in a post-independence context characterized by dual and often conflictual legal systems inspired by French and English colonialism. Justice Nyo'Wakai demonstrates how the conflict of judicial concepts, procedures and usages have led to the Francophone judicial system trying to impose itself on the Anglophone judicial system in Cameroon. Often reduced to toothless bulldogs by new constitutional dispensations informed largely by the French colonial legacy and Francophone realities, Anglophones have bemoaned the independence of the Judiciary identified with their Anglo-Saxon heritage. In the face of such domination and the highhandedness of the Executive, only mature cool headedness and the ability to bend over backwards on the part of Anglophone legal practitioners have contained the explosive situation and allowed for a gradual evolution of the Judicial System in Cameroon.
A wall-sized canvas by Twombly hanging in a purpose-built pavilion by Renzo Piano, commissioned by the Menil Collection in Houston, bears the scrawled inscription »Anatomy of Melancholy.« Untitled (Say Goodbye Catullus, to the Shores of Asia Minor) is the culminating statement of the artist’s maturity: begun in 1972, it was first exhibited in 1994. In this monumental cenotaph, Twombly’s painting displays phrases from Archilochos, Catullus, Keats and Rilke, as well as the title of Burton’s famous tome, worked into the fabric of the composition, integral to the iconic content. It is the aching heart of the select permanent exhibition of his oeuvre at the pavilion, known as the Twombly Gallery (www.menil.org/twombly.html). The austerity of Piano’s architectural setting, as well as the cunningly filtered Texas sunlight, makes this a site of cult, like the chapel containing the dark, final canvases of Mark Rothko, situated around the corner in the same urban grove of old oak. The setting is a modern Dodona, remote seat of the oaken oracle of Zeus, and it makes an evocative home for Twombly’s enigmatic constructions. These disarm conventional vocabularies of aesthetic response, drawing attention to words and snatches of verse as points of association and recognition. Looking at them involves siting a phrase such as »Anatomy of Melancholy« in other dimensions – in lines, patches, figures, colors.
G. A. Cohen argues that John Rawls’s focus on the basic structure of society as the exclusive subject of social justice is misguided. I argue that two understandings of the notion of basic structure seem to be present in the literature, either in implicit or in explicit terms. (1) According to the first, the basic structure is to be equated with a given set of institutions: if they endorse the right principles of justice, the basic structure of society is just; (2) According to the second, a society has a just basic structure if and only if its institutional web manages to realize the relevant principles of justice as well it can. In (2), the institutional structure is not a given: different social circumstances call for different institutional solutions in order to achieve a just basic structure overall. The first part of the paper make a case for (2), and explores some of its normative implications. The second part asks which consequences this understanding may have for the idea of a global basic structure.
In this paper, we present an open-source parsing environment (Tübingen Linguistic Parsing Architecture, TuLiPA) which uses Range Concatenation Grammar (RCG) as a pivot formalism, thus opening the way to the parsing of several mildly context-sensitive formalisms. This environment currently supports tree-based grammars (namely Tree-Adjoining Grammars (TAG) and Multi-Component Tree-Adjoining Grammars with Tree Tuples (TT-MCTAG)) and allows computation not only of syntactic structures, but also of the corresponding semantic representations. It is used for the development of a tree-based grammar for German.