40 research outputs found
Concession contract renegotiations : some efficiency versus equity dilemmas
No full textThe authors analyze the possibility of tradeoffs between efficiency and equity as well as the possibility of distributional conflicts in the context of renegotiation of infrastructure contracts in developing countries. To do so, they present a model in which contracts are awarded by auctioning the right to operate an infrastructure service to a private monopoly, and consider the possibility of renegotiation. To identify the potential sources of tradeoffs, they trackthe possible outcomes of different renegotiation strategies for the monopoly running the concession and for the two groups of consumers-rich and poor-who alternate in power according to a majority voting rule. Among the model? most important policy implications is this: if having firm-driven renegotiations is a major concern, efficiency should not be the only consideration in selecting an operator. Indeed, consumers may want to award the concession to a less efficient firm if that would reduce the probability of renegotiation, since a lower probability of firm-driven renegotiations (due to demand shocks, for example) is associated with higher welfare for all service users.Environmental Economics&Policies,Labor Policies,Markets and Market Access,Economic Theory&Research,International Terrorism&Counterterrorism,Economic Theory&Research,Environmental Economics&Policies,Markets and Market Access,Access to Markets,International Terrorism&Counterterrorism
The creation of Yorkshireness: Cultural identities in Yorkshire c.1850-1918
No full textTHE rapid expansion, wider distribution and increased readership of print media in the latter half of the nineteenth century helped to foster the process that has been described as the nationalisation of English culture. In a parallel process, however, the same media could also be deployed to construct and to propagate regional cultures and identities. This thesis, concentrating on the period c.1850-1918, uses Yorkshire as a case study. The employment of county boundaries and structures as a delimitation for historical research can be questioned. But it is defensible in the case of the cultural study of a county that, in spite of its size, heterogeneity and industrial transformation, had acquired a set of identities and stereotypes which evolved during the early-modern period and were retained, refined and celebrated in the industrial age. Although it had no political basis, Yorkshireness remained a powerful sub-identity within England, the United Kingdom and the wider British world.
By examining the newspaper press, weekly periodicals, dialect almanacs and regional fiction, the thesis explores the evolution and the dissemination of Yorkshire’s cultural identity in an age of popular print. There is also an analysis of attempts to find a deterministic basis for Yorkshire character and a description of county societies in the UK and overseas. The evolution of folkloristic Yorkshire identities and symbols is traced, and illustrated dialect postcards of the early-twentieth century are analysed, on the grounds that they were a widely-transmitted source of Yorkshire stereotypes.
Individuals who played a role in the construction of Yorkshireness include the writer James Burnley, the folklorist and humorist Richard Blakeborough, the novelists Halliwell Sutcliffe and William Riley, the dialect writers Charles Rogers and John Hartley, the cartoonist Arthur North and the University of Leeds academic Professor Frederic Moorman, who conceived the project for eisteddfod equivalents in Yorkshire. The conclusion is that Victorian and Edwardian print media and illustrated ephemera were used extensively to construct and convey a sense of Yorkshireness, acting as a countervailing force to the tendency towards nationalisation of culture, and that in the absence of a fully negotiated concept of universal Englishness, county identity was an important factor at home and overseas
Evaluating the adaptive potential of the European eel: is the immunogenetic status recovering?
No full textThe recent increased integration of evolutionary theory into conservation programs has greatly improved our ability to protect endangered species. A common application of such theory links population dynamics and indices of genetic diversity, usually estimated from neutrally evolving markers. However, some studies have suggested that highly polymorphic adaptive genes, such as the immune genes of the Major Histocompatibility Complex (MHC), might be more sensitive to fluctuations in population dynamics. As such, the combination of neutrally- and adaptively-evolving genes may be informative in populations where reductions in abundance have been documented. The European eel (Anguilla anguilla) underwent a drastic and well-reported decline in abundance in the late 20th century and still displays low recruitment. Here we compared genetic diversity indices estimated from neutral (mitochondrial DNA and microsatellites) and adaptive markers (MHC) between two distinct generations of European eels. Our results revealed a clear discrepancy between signatures obtained for each class of markers. Although mtDNA and microsatellites showed no changes in diversity between the older and the younger generations, MHC diversity revealed a contemporary drop followed by a recent increase. Our results suggest ongoing gain of MHC genetic diversity resulting from the interplay between drift and selection and ultimately increasing the adaptive potential of the species
Divergence thresholds and divergent biodiversity estimates: can metabarcoding reliably describe zooplankton communities?
No full textDNA metabarcoding is a promising method for describing communities and estimating biodiversity. This approach uses high-throughput sequencing of targeted markers to identify species in a complex sample. By convention, sequences are clustered at a predefined sequence divergence threshold (often 3%) into operational taxonomic units (OTUs) that serve as a proxy for species. However, variable levels of interspecific marker variation across taxonomic groups make clustering sequences from a phylogenetically diverse dataset into OTUs at a uniform threshold problematic. In this study, we use mock zooplankton communities to evaluate the accuracy of species richness estimates when following conventional protocols to cluster hypervariable sequences of the V4 region of the small subunit ribosomal RNA gene (18S) into OTUs. By including individually tagged single specimens and “populations” of various species in our communities, we examine the impact of intra- and interspecific diversity on OTU clustering. Communities consisting of single individuals per species generated a correspondence of 59–84% between OTU number and species richness at a 3% divergence threshold. However, when multiple individuals per species were included, the correspondence between OTU number and species richness dropped to 31–63%. Our results suggest that intraspecific variation in this marker can often exceed 3%, such that a single species does not always correspond to one OTU. We advocate the need to apply group-specific divergence thresholds when analyzing complex and taxonomically diverse communities, but also encourage the development of additional filtering steps that allow identification of artifactual rRNA gene sequences or pseudogenes that may generate spurious OTUs
Toward accurate molecular identification of species in complex environmental samples: testing the performance of sequence filtering and clustering methods
No full textMetabarcoding has the potential to become a rapid, sensitive, and effective approach for identifying species in complex environmental samples. Accurate molecular identification of species depends on the ability to generate operational taxonomic units (OTUs) that correspond to biological species. Due to the sometimes enormous estimates of biodiversity using this method, there is a great need to test the efficacy of data analysis methods used to derive OTUs. Here, we evaluate the performance of various methods for clustering length variable 18S amplicons from complex samples into OTUs using a mock community and a natural community of zooplankton species. We compare analytic procedures consisting of a combination of (1) stringent and relaxed data filtering, (2) singleton sequences included and removed, (3) three commonly used clustering algorithms (mothur, UCLUST, and UPARSE), and (4) three methods of treating alignment gaps when calculating sequence divergence. Depending on the combination of methods used, the number of OTUs varied by nearly two orders of magnitude for the mock community (60–5068 OTUs) and three orders of magnitude for the natural community (22–22191 OTUs). The use of relaxed filtering and the inclusion of singletons greatly inflated OTU numbers without increasing the ability to recover species. Our results also suggest that the method used to treat gaps when calculating sequence divergence can have a great impact on the number of OTUs. Our findings are particularly relevant to studies that cover taxonomically diverse species and employ markers such as rRNA genes in which length variation is extensive
Early detection of aquatic invaders using metabarcoding reveals a high number of non-indigenous species in Canadian ports
No full textAim Invasive species represent one of the greatest threats to biodiversity. The ability to detect non-indigenous species (NIS), particularly those present at low abundance, is limited by difficulties in performing exhaustive sampling and in identifying species. Here we sample zooplankton from 16 major Canadian ports and apply a metabarcoding approach to detect NIS. Location Marine and freshwater ports along Canadian coastlines (Pacific, Arctic, Atlantic) and the Great Lakes. Methods We amplified the V4 region of the small subunit ribosomal DNA (18S) and used two distinct analytic protocols to identify species present at low abundance. Taxonomic assignment was conducted using BLAST searches against a local 18S sequence database of either (i) individual reads (totalling 7,733,541 reads) or (ii) operational taxonomic units (OTUs) generated by sequence clustering. Phylogenetic analyses were performed to confirm the identity of reads with ambiguous taxonomic assignment. Results Taxonomic assignment of individual reads identified 379 zooplankton species at a minimum sequence identity of 97%. Of these, 24 species were identified as NIS, 11 of which were detected in previously unreported locations. When reads were clustered into OTUs prior to taxonomic assignment, six NIS were no longer detected and an additional NIS was falsely identified. Phylogenetic analyses revealed that sequences belonging to closely related species clustered together into shared OTUs as a result of low interspecific variation. NIS can thus be misidentified when their sequences join the OTUs of more abundant native species. Main conclusions Our results reveal the power of the metabarcoding approach, whilst also highlighting the need to account for potentially low levels of genetic diversity when processing data, to use barcode markers that allow differentiation of closely related species and to continue building comprehensive sequence databases that allow reliable and fine-scale taxonomic designation
Richard Cobden, educationist, economist and statesman.
No full textThe aim of the thesis is to show that Richard Cobden
(1804-1865) deserves to be given a significant place in
the history of political, economic and social thought and
also full credit for a range of statesmanship which went
far beyond his well known part in the repeal of the Corn
Laws and the Anglo-French Commercial Treaty of 1860.
Historians have not sufficiently recognised that Cobden
sought to make fundamental changes in British society and
that he tried to initiate them by piecemeal constitutional
methods. He also believed that the British example would
have a powerful influence on other countries and thus
contribute to a new world order.
Cobden had a coherent, although unsystematised,
philosophy, based on certain major assumptions. They were,
firstly, that social progress depends on the interaction
of economic, moral and religious and educational factors;
secondly that progress towards a real political democracy
depends on progress in the former areas. A special problem
in explaining Cobden's philosophy is the fact that the
ideas of two important thinkers with whom he was associated,
George Combe (1788-1858), phrenologist (psychologist) and
Frederic Bastiat (1801-1850), economist, have been belittled
and neglected since Cobden's death. Therefore, the analysis of Cobden's thought necessitated an effort to "rehabilitate't these two thinkers.
Cobden's efforts to transform British politics and society were only partially successful in Britain's
adoption of free trade, a policy not properly understood
by most statesmen and commercial men. His work for
common schools, international schools, lyceums and
educative popular newspapers was a failure and soon
forgotten; his efforts to reform British foreign policy
and implement arms control also failed. After his death,
his followers failed to develop satisfactorily his ideas
for application to social and international problems. These
ideas still have considerable potential
t10,c12-18:2-Induced Milk Fat Depression is Less Pronounced in Cows Fed High-Concentrate Diets
No full textInternational audienceIn intensively reared dairy cows, milk fat secretion is reduced in response to high-concentrate diets and it is often referred to as the ‘‘milk fat depression’’ (MFD) syndrome. Some trans fatty acid (FA) isomers produced in the rumen of the cows, including t10,c12-18:2, are known for their inhibitory effect on mammary lipogenesis. To study whether this effect depends on the basal diet, duodenal infusions of t10,c12-18:2 were performed on cows fed four different diets (a factorial arrangement of forage:concentrate ratio and linseed oil supplementation). The overall response obtained with t10,c12-18:2 infusion was consistent with previous studies: a decrease in milk fat content and yield without significant variations in milk yield. Mean transfer efficiency of infused 10,c12-18:2 was 19.6%. However, the decrease in milk fat and FA yields (both de novo synthesis and preformed long-chain FA) was less pronounced in cows fed high-concentrate diets (-27% of the initial level), compared with cows fed low-concentrate diets (-42% of initial level). This difference was independent of dietary oil supplementation and milk FA yield before infusion. Results pertaining to effects of dietary forage:concentrate ratio were confirmed by statistical meta-analysis of data from previously published t10,c12- 18:2 infusion experiments. This study shows that in cows fed MFD diets the mammary gland becomes more resistant to or experiences a lower response potential to further inhibition of lipogenesis and/or delta-9 desaturation of FA
In situ Metabolism and Biogeography of Phototrophic Consortia
No full text>>Novel bacteriochlorophyll e structures and species-specific variability of pigment composition in green sulfur bacteria<<
The relative composition of bacteriochlorophyll (BChl) homologs in five different strains of brown-colored green sulfur bacteria was investigated by HPLC-MS/MS and NMR analyses. In addition, the effect of incubation light intensities on homolog distribution was studied in one of the strains (strain Dagow III). A total of 23 different BChl e structures were detected and comprise four homologous porphyrin ring systems and eight different esterifying alcohols. Several BChl e structures are novel. These include a C-8 ethyl, C-12 methyl [E,M] BChl eF homolog which was identified by 1H-NMR analyses of the isolated, main farnesyl homologs (BChl eF). In addition, five previously unknown homolog series with dodecanol, pentadecenol, tetradecanol, hexadecenol and phytol as the esterifying alcohols were detected. The composition of BChl e homologs from the five strains of green sulfur bacteria differed with respect to the relative abundance of the homologs (BChl eF: 25.6 to 67.0% of total BChl e content in stationary cultures). In strain Dagow III, the abundance of BChl eF homologs decreased upon entry into the stationary phase. In all free-living strains, the abundance of BChl eF was increased when the relative carotenoid content was low. The present results provide a more detailed picture of pigment composition in chlorosomes and thus will help to elucidate their structure and function. Furthermore, the newly discovered BChl e molecules are valuable biomarkers for the study of the occurrence and the metabolism of green sulfur bacteria in past and present ecosystems.
>>Characterization and in situ carbon metabolism of phototrophic consortia<< A dense population of the phototrophic consortium "P. roseum" was investigated in the chemocline of a temperate holomictic lake (Lake Dagow, Brandenburg, Germany). Fluorescent in situ hybridization revealed that the brown-colored epibionts of "P. roseum" constituted up to 37 % of total bacterial cell numbers and up to 88 % of all green sulfur bacteria present in the chemocline. Specific amplification of 16S rRNA gene fragments of green sulfur bacteria and DGGE fingerprinting yielded a maximum of 4 different DNA bands depending on the year of study, indicating a low diversity of green sulfur bacteria. The 465 bp-long 16S rRNA gene sequence of the epibiont of "P. roseum" was obtained after sorting individual consortia by micromanipulation, followed by a highly sensitive PCR. The sequence obtained represents a new phylotype within the radiation of green sulfur bacteria. A maximum of light-dependent H14CO3- fixation in the chemocline in the presence of DCMU suggested anaerobic autotrophic growth of the green sulfur bacteria. The metabolism of the epibionts was further studied by determination of stable isotope ratios (d13C) of their specific biomarkers. Analysis of photosynthetic pigments by HPLC revealed the presence of high concentrations of BChl e and smaller amounts of BChl a, d and Chl a in the chemocline. Unexpectedly, isorenieratene and b-isorenieratene, carotenoids typical for other brown-colored members of the green sulfur bacteria, were absent. Instead, four different esterifying alcohols of BChl e were isolated as biomarkers of green sulfur bacterial epibionts, and their d13C measured. Farnesol, tetradecanol, hexadecanol and hexadecenol all were significantly enriched in 13C compared to bulk dissolved and particulate organic carbon, and compared to the biomarkers of purple sulfur bacteria. The difference (Dd13C) between d13C values of farnesol, the major esterifying alcohol of BChl e, and CO2 was -7.1‰, which provides clear evidence for a photoautotrophic mode of growth of the green sulfur bacterial epibionts of "P. roseum" in situ.
>>The significance of organic carbon compounds for in situ metabolism and chemotaxis of phototrophic consortia<<
The significance of organic carbon substrates for the chemotaxis and physiology of phototrophic consortia was investigated in a dense chemocline community of "Pelochromatium roseum". For the first time, the monopolar monotrichous flagellation of the central bacterium could be visualized. In situ, intact motile "P. roseum" consortia were strongly attracted by sulfide and 2-oxoglutarate, which indicated a potential role of these compounds in the metabolism of "P. roseum". In chemocline water samples, 2-[14C(U)]-oxoglutarate was utilized at nanomolar concentrations (half saturation constant of uptake Kt ≤ 10 - 40 nM), and at a maximum uptake rate of Vmax ≈ 6 nM·h-1. The calculated turnover of 2-oxoglutarate at in situ concentrations was ~6 hours. Microautoradiography of chemocline water samples revealed that 87.5 % of the "P. roseum" consortia incorporated 2-oxoglutarate when both light and sulfide were present, whereas uptake was detected in less than 1.4% of the consortia if either light or sulfide were absent. Since the green sulfur bacterial epibionts in "P. roseum" have been shown to grow autotrophically, 2-oxoglutarate most likely is taken up and utilized by the central bacterium. Thus, our results indicate that incorporation of 2-oxoglutarate by the central bacterium is regulated by the metabolic state of the green sulfur bacterial epibionts.
Diversity and biogeography of phototrophic consortia
Motile phototrophic consortia are highly regular associations in which numerous cells of green sulfur bacteria surround a flagellated colorless b-proteobacterium in the center. To date, seven different morphological types have been described. In addition, two immotile associations involving green sulfur bacteria are known. Employing a culture-independent approach, different types of phototrophic consortia were mechanically isolated by micromanipulation from 14 freshwater lakes and ponds and partial 16S rRNA gene sequences of the green sulfur bacterial epibionts were determined. In all cases, phototrophic consortia with the same morphology and from the same habitat contained only one single epibiont phylotype. None of the epibiont 16S rRNA gene sequences have so far been detected in free-living green sulfur bacteria, indicating that the interaction between epibionts and chemotrophic bacteria in the phototrophic consortia is an obligate one. Morphologically indistinguishable phototrophic consortia collected from different lakes contained different epibionts. Overall, 20 different types of epibionts were detected in the present study. Based on our phylogenetic analysis, the epibiont sequences are not monophyletic and arose from different ancestors which independently developed the ability to form symbiotic associations. In the majority of lakes investigated, different types of phototrophic consortia were found to co-occur. Based on this finding, morphologically distinct types of consortia occupy different ecological niches. This is supported by the results of chemotaxis assays which revealed that different populations of the consortia "Chlorochromatium aggregatum" and "Pelochromatium roseum" were attracted by different organic carbon substrates and different reduced sulfur compounds. The present study thus demonstrates a high diversity, the presence of multiple niches, and a nonstatistical biogeographical distribution of phototrophic consortia in the natural environment
Choosing policy instruments for pollution control : a review
No full textThis paper presents the design of cost effective interventions to protect the environment from excessive pollution in developing countries. The concept of intervention is motivated by the typical explanation for environmental problems in economic theory--external effects. The aim of the paper is to review the relevant theoretical and empirical economic literature in order: (a) to distill the principal lessons and evaluate general rules of thumb; and (b) to identify gaps that need to be filled in order to make them more accessible and relevant to developing countries. The paper defines broadly the range of policy instruments that can be used to address pollution problems in developing countries. It includes instruments that have traditionally been in the realm of public finance, such as taxes, prices and subsidies. But it also covers regulations and other instruments designed to affect the amount of pollution or to mitigate its damage. To limit the scope of this paper, the authors treat pollution control policies, but not policies to address other environmental problems, such as soil erosion, deforestation, desertification or other natural resource problems. Many of the principles presented, however, broadly relate to the problem of correcting for external effects, and can be applied to these other problems as well. It also focuses on domestic problems and does not deal explicitly with trans-national or global pollution externalities.Economic Theory&Research,Water and Industry,Health Monitoring&Evaluation,Pollution Management&Control,Environmental Economics&Policies
