171 research outputs found
A new Colhuehuapian (early Miocene) caviomorph rodent from Patagonia and preliminary considerations on the early evolution of the superfamily Octodontoidea
Octodontoidea includes the most diverse superfamily of South American rodents in terms of morphology, taxonomy and ecology. The morphological and taxonomic diversity are evident since their earliest records (late Eocene?-early Oligocene). Nowadays there are two major lineages, the Echimyidae (including Myocastor) and the Octodontidae.the superfamily are not clear and need to be revised. In this contribution a new octodontoid rodent Nevertheless, the phylogenetic relationships of these two lineages with the most ancient members of from Colhuehuapian levels (early Miocene) of the Trelew Member (Sarmiento Formation) at Gaiman, Chubut Province, Argentina, is described. It is known through teeth and partially preserved jaws. This new taxon is characterized by having brachydont cheek teeth and the retention of DP4/dp4; it shares with Caviocricetus (Colhuehuapian) the general morphology of the upper cheek teeth and the terraced occlusal surfaces. The development of the metalophulid II in the lower cheek teeth and the pentalophodont premolar morphology are similar to that of Prospaniomys (Colhuehuapian). A cladistic analysis was performed in order to evaluate the relationships of the new taxon; we used 22 taxa and 39 dental and mandibular characters, since they are the only ones that can be tested in the new taxon. The results indicate this new specimen forms, with Caviocricetus and Plesiacarechimys (Colloncuran, middle Miocene), the stem group of a clade constituted by the acaremyids (+ Acarechimys), and by the fossil echimyids traditionally included within the subfamily Adelphomyinae. Moreover, we verified a variety of evolutionary lines within the superfamily that are not directly related with modern octodontoids; some of these lineages would have diverged in pre-Deseadan times (Oligocene) and persisted until the middle Miocene, retaining a generalized dental morphology for the superfamily.Sesiones libresFacultad de Ciencias Naturales y Muse
Social Preferences, Skill Segregation and Wage Dynamics
We study the earning structure and the equilibrium asignment of workers to firms in a model in which workers have social preferences, and skills are perfectly substitutable in production. Firms offer long-term contracts, and we allow for frictions in the labour market in the form of mobility costs. The model delivers specific predictions about the nature of worker flows, about the characteristic of workplace skill segregation, and about wage dispersion both within and cross firms. We shows that long-term contracts in the resence of social preferences associate within-firm wage dispersion with novel "internal labour market" features such as gradual promotions, productivity-unrelated wage increases, and downward wage flexibility. These three dynamic features lead to productivity-unrelated wage volatily within firms.Publicad
A software tool for estimation of burden of infectious diseases in Europe using incidence-based disability adjusted life years
The burden of disease framework facilitates the assessment of the health impact of diseases through the use of summary measures of population health such as Disability- Adjusted Life Years (DALYs). However, calculating, interpreting and communicating the results of studies using this methodology poses a challenge. The aim of the Burden of Commu
Impact of infectious diseases on population health using incidence-based disability-adjusted life years (DALYs)
Background and aims: The Burden of Communicable Diseases in Europe (BCoDE) study aimed to calculate disability-adjusted life years (DALYs) for 31 selected diseases in the European Union (EU) and European Economic Area (EEA). Methods: DALYs were estimated using an incidence-based and pathogen-based approach. Incidence was estimated through assessment of data availability and quality, and a correction was applied for under-estimation. Calculation of DALYs was performed with the BCoDE software toolkit without applying time discounting and age-weighting. Results: W
Biodiversity and structure of spider communities along a metal pollution gradient
The objective of the study was to determine whether long-term metal pollution affects communities of epigeal spiders (Aranea), studied at three taxonomic levels: species, genera, and families. Biodiversity was defined by three indices: the Hierarchical Richness Index (HRI), Margalef index (DM) and Pielou evenness index (J). In different ways the indices describe taxa richness and the distribution of individuals among taxa. The dominance pattern of the communities was described with four measures: number of dominant species at a site, percentage of dominant species at a site, average dominant species abundance at a site, and the share of the most numerous species (Alopecosa cuneata) at a site. Spiders were collected along a metal pollution gradient in southern Poland, extending ca. 33 km from zinc and lead smelter to an uncontaminated area. The zinc concentration in soil was used as the pollution index.The study revealed a significant effect of metal pollution on spider biodiversity as described by HRI for species (p = 0.039), genera (p = 0.0041) and families (p = 0.0147), and by DM for genera (p = 0.0259) and families (p = 0.0028). HRI correlated negatively with pollution level, while DM correlated positively. This means that although broadly described HRI diversity decreased with increasing pollution level, species richness increased with increasing contamination. Mesophilic meadows were generally richer. Pielou (J) did not show any significant correlations. There were a few evidences for the intermediate disturbance hypothesis: certain indices reached their highest values at moderate pollution levels rather than at the cleanest or most polluted sites
Explaining the U-Shape of the Referral Hiring Pattern in a Search Model with Heterogeneous Workers
Environmental Levels of the Antiviral Oseltamivir Induce Development of Resistance Mutation H274Y in Influenza A/H1N1 Virus in Mallards
Oseltamivir (Tamiflu®) is the most widely used drug against influenza infections and is extensively stockpiled worldwide as part of pandemic preparedness plans. However, resistance is a growing problem and in 2008–2009, seasonal human influenza A/H1N1 virus strains in most parts of the world carried the mutation H274Y in the neuraminidase gene which causes resistance to the drug. The active metabolite of oseltamivir, oseltamivir carboxylate (OC), is poorly degraded in sewage treatment plants and surface water and has been detected in aquatic environments where the natural influenza reservoir, dabbling ducks, can be exposed to the substance. To assess if resistance can develop under these circumstances, we infected mallards with influenza A/H1N1 virus and exposed the birds to 80 ng/L, 1 µg/L and 80 µg/L of OC through their sole water source. By sequencing the neuraminidase gene from fecal samples, we found that H274Y occurred at 1 µg/L of OC and rapidly dominated the viral population at 80 µg/L. IC50 for OC was increased from 2–4 nM in wild-type viruses to 400–700 nM in H274Y mutants as measured by a neuraminidase inhibition assay. This is consistent with the decrease in sensitivity to OC that has been noted among human clinical isolates carrying H274Y. Environmental OC levels have been measured to 58–293 ng/L during seasonal outbreaks and are expected to reach µg/L-levels during pandemics. Thus, resistance could be induced in influenza viruses circulating among wild ducks. As influenza viruses can cross species barriers, oseltamivir resistance could spread to human-adapted strains with pandemic potential disabling oseltamivir, a cornerstone in pandemic preparedness planning. We propose surveillance in wild birds as a measure to understand the resistance situation in nature and to monitor it over time. Strategies to lower environmental levels of OC include improved sewage treatment and, more importantly, a prudent use of antivirals
RNAcentral 2021: secondary structure integration, improved sequence search and new member databases
RNAcentral is a comprehensive database of non-coding RNA (ncRNA) sequences that provides a single access point to 44 RNA resources and >18 million ncRNA sequences from a wide range of organisms and RNA types. RNAcentral now also includes secondary (2D) structure information for >13 million sequences, making RNAcentral the world’s largest RNA 2D structure database. The 2D diagrams are displayed using R2DT, a new 2D structure visualization method that uses consistent, reproducible and recognizable layouts for related RNAs. The sequence similarity search has been updated with a faster interface featuring facets for filtering search results by RNA type, organism, source database or any keyword. This sequence search tool is available as a reusable web component, and has been integrated into several RNAcentral member databases, including Rfam, miRBase and snoDB. To allow for a more fine-grained assignment of RNA types and subtypes, all RNAcentral sequences have been annotated with Sequence Ontology terms. The RNAcentral database continues to grow and provide a central data resource for the RNA community. RNAcentral is freely available at https://rnacentral.org
Does codetermination affect the composition of variable versus fixed parts of executive compensation?
Contrary to previous literature we hypothesize that interests of labor may well – like that of shareholders – aim at securing the long-run survival of the firm. Consequently, employee representatives on the supervisory board could well have an interest in increasing incentive-based compensation to avoid excessive risk taking and short-run orientated decisions. We compile unique panel data on executive compensation over the periods 2006 to 2011 for 405 listed companies and use a Hausman-Taylor approach to estimate the effect of codetermination on the compensation design. Finally, codetermination has a significantly positive effect on performance-based components of compensation, which supports our hypothesis
The toxicokinetics cell demography model to explain metal kinetics in terrestrial invertebrates
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