423 research outputs found

    A tale of two cities: The impact of airline mergers and consolidation at London and New York

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    This paper considers the changes to airline networks, service patterns, and competition that have taken place as a result of recent airline mergers on both sides of the North Atlantic as well as through transatlantic alliances. Capacity, frequency and the competitive position are studied at London and New York with the use of schedule data within different markets in which measures of market concentration are evaluated. International Civil Aviation Organization data is employed to examine load factors on international routes, and UK Civil Aviation Authority data to consider the distribution of traffic between airports in London. It is shown that the effectiveness of the hubs has increased, with enhanced efficiency for surviving airlines, through fewer competitors, an enlarged network and greater control of capacity. Potential concerns are identified however, regarding passenger choice,pricing, and service options that suggest the industry is moving toward an oligopoly. Smaller cities are also seen to be the losers from consolidation with slot divestments favoring increased service in the dense markets, with many regional links being axed altogether. The paper supplements the literature on airline consolidation, with a particular focus on the two biggest markets in the world—London and New York—which demonstrate some similar but also some different issues. Both airline network impacts and choice, and service for local consumers are considered

    Convergent evolution of SWS2 opsin facilitates adaptive radiation of threespine stickleback into different light environments

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    Repeated adaptation to a new environment often leads to convergent phenotypic changes whose underlying genetic mechanisms are rarely known. Here, we study adaptation of color vision in threespine stickleback during the repeated postglacial colonization of clearwater and blackwater lakes in the Haida Gwaii archipelago. We use whole genomes from 16 clearwater and 12 blackwater populations, and a selection experiment, in which stickleback were transplanted from a blackwater lake into an uninhabited clearwater pond and resampled after 19 y to test for selection on cone opsin genes. Patterns of haplotype homozygosity, genetic diversity, site frequency spectra, and allele-frequency change support a selective sweep centered on the adjacent blue- and red-light sensitive opsins SWS2 and LWS. The haplotype under selection carries seven amino acid changes in SWS2, including two changes known to cause a red-shift in light absorption, and is favored in blackwater lakes but disfavored in the clearwater habitat of the transplant population. Remarkably, the same red-shifting amino acid changes occurred after the duplication of SWS2 198 million years ago, in the ancestor of most spiny-rayed fish. Two distantly related fish species, bluefin killifish and black bream, express these old paralogs divergently in black- and clearwater habitats, while sticklebacks lost one paralog. Our study thus shows that convergent adaptation to the same environment can involve the same genetic changes on very different evolutionary time scales by reevolving lost mutations and reusing them repeatedly from standing genetic variation

    Genomic changes underlying repeated niche shifts in an adaptive radiation

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    In adaptive radiations, single lineages rapidly diversify by adapting to many new niches. Little is known yet about the genomic mechanisms involved, that is, the source of genetic variation or genomic architecture facilitating or constraining adaptive radiation. Here, we investigate genomic changes associated with repeated invasion of many different freshwater niches by threespine stickleback in the Haida Gwaii archipelago, Canada, by resequencing single genomes from one marine and 28 freshwater populations. We find 89 likely targets of parallel selection in the genome that are enriched for old standing genetic variation. In contrast to theoretical expectations, their genomic architecture is highly dispersed with little clustering. Candidate genes and genotype-environment correlations match the three major environmental axes predation regime, light environment, and ecosystem size. In a niche space with these three dimensions, we find that the more divergent a new niche from the ancestral marine habitat, the more loci show signatures of parallel selection. Our findings suggest that the genomic architecture of parallel adaptation in adaptive radiation depends on the steepness of ecological gradients and the dimensionality of the niche space

    A case study for teaching information literacy skills

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    <p>Abstract</p> <p>Background</p> <p>The Internet has changed contemporary workplace skills, resulting in a need for proficiency with specific digital, online and web-based technologies within the fields of medicine, dentistry and public health. Although younger students, generally under 30 years of age, may appear inherently comfortable with the use of technology-intensive environments and digital or online search methods, competence in information literacy among these students may be lacking.</p> <p>Methods</p> <p>This project involved the design and assessment of a research-based assignment to help first-year, graduate-level health science students to develop and integrate information literacy skills with clinical relevance.</p> <p>Results</p> <p>One cohort of dental students (n = 78) was evaluated for this project and the results demonstrate that although all students were able to provide the correct response from the content-specific, or technology-independent, portion of the assignment, more than half (54%) were unable to demonstrate competence with a web-based, technology-dependent section of this assignment. No correlation was found between any demographic variable measured (gender, age, or race).</p> <p>Conclusion</p> <p>More evidence is emerging that demonstrates the need for developing curricula that integrates new knowledge and current evidence-based practices and technologies, traditionally isolated from graduate and health-care curricula, that can enhance biomedical and clinical training for students. This study provides evidence, critical for the evaluation of new practices, which can promote and facilitate the integration of information literacy into the curriculum.</p

    Parton distributions in the virtual photon target up to NNLO in QCD

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    Parton distributions in the virtual photon target are investigated in perturbative QCD up to the next-to-next-to-leading order (NNLO). In the case Λ2P2Q2\Lambda^2 \ll P^2 \ll Q^2, where Q2-Q^2 (P2-P^2) is the mass squared of the probe (target) photon, parton distributions can be predicted completely up to the NNLO, but they are factorisation-scheme-dependent. We analyse parton distributions in two different factorisation schemes, namely MSˉ\bar{\rm MS} and DISγ{\rm DIS}_{\gamma} schemes, and discuss their scheme dependence. We show that the factorisation-scheme dependence is characterised by the large-xx behaviours of quark distributions. Gluon distribution is predicted to be very small in absolute value except in the small-xx region.Comment: 28 pages, 5 figures, version to appear in Eur. Phys. J.

    Transplantation tolerance: lessons from experimental rodent models

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    Immunological tolerance or functional unresponsiveness to a transplant is arguably the only approach that is likely to provide long-term graft survival without the problems associated with life-long global immunosuppression. Over the past 50 years, rodent models have become an invaluable tool for elucidating the mechanisms of tolerance to alloantigens. Importantly, rodent models can be adapted to ensure that they reflect more accurately the immune status of human transplant recipients. More recently, the development of genetically modified mice has enabled specific insights into the cellular and molecular mechanisms that play a key role in both the induction and maintenance of tolerance to be obtained and more complex questions to be addressed. This review highlights strategies designed to induce alloantigen specific immunological unresponsiveness leading to transplantation tolerance that have been developed through the use of experimental models

    Computer software for business and specific purposes in wood industry

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    V 211 slovenskih mikro in majhnih lesnih podjetjih, katerih osnovna dejavnost (po SKD) zajema proizvodnjo pohištva za poslovne prostore, proizvodnjo kuhinjskega pohištva in proizvodnjo drugega pohištva, smo preučili razširjenost ter uporabo poslovnih in namenskih računalniških programov. Raziskava je temeljila na primerjalni analizi in oceni stanja programske opreme. Oceno stanja smo izvedli s pomočjo ankete, ki smo jo distribuirali prek različnih medijev. Odziv na anketo je bil v povprečju 23,7 %. Ocenimo lahko, da so računalniški programi v mikro in majhnih lesnih podjetjih na nekaterih področjih intenzivneje uporabljani kot na drugih. Ugotovili smo, da podjetja v večini uporabljajo pri poslovanju pisarniške programe, predvsem tiste podjetja Microsoft. Uporaba specializirane programske opreme je še precej omejena, saj jo pri poslovanju uporablja le 40 % preučevanih podjetij. Nekoliko bolj uporabljajo programsko opremo namenjeno konstruiranju (60 %).The range and usage of computer software for business and specific purposes were researched in 211 micro and minor wood firms, encompasing the production of office furniture, kitchen furniture and some other furniture as the basic activity, according to Statistical Classification Activities (SCA). The research was based on comparative analysis and software condition evaluation. Evaluation of the current situation was carried out by means of a questionnaire, distributed with the help of media. The response was as high as 23.7 %. It can be estimated that the computer software in these micro and minor wood firms is used more often in some areas than in others. It was found out that the firms use mainly office software- especially Microsoft ones. The usage of specialized software equipment is still quite limited in these firms. Only 40 % of the tested firms use is software for their business, meanwhile the equipment designed for construction is more frequently used (60 %)
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