881 research outputs found

    Going Back to the Roots

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    New Gilded Age or Old Normal?

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    Since the mid-1970s, inequality has increased under Democratic as well as Republican administrations and Congresses. In retrospect, the four and a half decades from 1933 to 1978 were a historical aberration. The longer-term trend toward more inequality in capitalist economies, which prevailed before this period, has re­sumed after it. That leads us to conclude that there may well be no technocratic or tax policy fix for capitalism’s tendency to generate ever more inequality

    Local extinctions of birds in forest fragments in the Santa Elena region, Central Andes, Colombia

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    Los registros históricos de la avifauna de la región de Santa Elena (Andes centrales colombianos), realizados entre 1879 y 1952, fueron comparados con los de las aves presentes actualmente en tres fragmentos remanentes de bosque de 41, 129 y 136 ha. De las 132 especies presentes originalmente solo se conservan 64 en los tres fragmentos. En los tres fragmentos han desaparecido el 78%, el 66% y el 63% de sus especies. Las especies con alta especificidad de hábitat, con peso corporal de 51–100 g, las que se alimentan en el estrato arbóreo y las que lo hacen en troncos tendieron a presentar una proporción de extinción mayor a lo esperado. Sin embargo, no hubo diferencias estadísticamente significativas entre la proporción de especies extintas observada y esperada para ninguna de las categorías (gremio trófico, estrato de alimentación, tamaño corporal y especificidad de hábitat), lo que indica que todos los grupos presentaron la misma vulnerabilidad a la extinción. El peso promedio de las aves extintas fue similar al de las aves aún presentes en los tres fragmentos. Las especies de las familias Grallaridae, Cotingidae, Thraupidae, Trogonidae y de la subfamilia Dendrocolaptinae fueron las más afectadas. Se discute por qué las características ecológicas evaluadas pueden no estar relacionadas con la extinción local de aves en estos fragmentos de bosque.We compared historic records from 1879 until 1952 of birds of Santa Elena region (Colombian central Andes) with those from a recent survey in three forest fragments of 41, 129 and 136 ha. Only 64 out of the 132 original species still remain in the three fragments; 78%, 66% and 63% of the original species have disappeared from the fragments. Species with high habitat specificity, those with body mass of 51–100 g, those which forage in the arboreal stratum, and those which forage on trunks showed a tendency to suffer more extinctions than expected. However, there were no statistical differences between observed and expected proportions of extinctions in any of the categories (trophic guild, foraging stratum, body mass and habitat specificity), indicating that all the bird groups presented the same vulnerability to extinction. Mean body mass of extinct birds was similar to that of the birds still remaining in the fragments. Species from the families Grallaridae, Cotingidae, Thraupidae, Trogonidae and from the subfamily Dendrocolaptinae were the most affected. We discuss why the evaluated ecological features could not be related with local extinction of bird species in these forest fragments

    Timing and magnitude of net methylmercury effects on waterbird reproductive output are dependent on food availability.

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    Mercury (Hg) is a globally distributed pollutant. Its sub-lethal effects on reproduction of birds have been used as indicators of contamination and of potential demographic effects. However, studies typically used single endpoints that might not be representative of entire reproductive cycle. To estimate timing and net cumulative effects of Hg exposure under field conditions, we used observational data over 11 years from >1200 nests of great egrets breeding under temporally and spatially varying food availability and Hg exposures in the Florida Everglades. We collected measures of fish biomass and availability (>100 locations annually) and used four avian reproductive endpoints that represented the entire breeding cycle. We calculated net reproductive loss by adding estimated Hg effects on failures prior to egg laying, clutch size, hatching success and nestling survival in response to food availability and Hg exposure. To validate and assess results of the observational egret study, we ran the same analyses with data of captive breeding white ibises experimentally exposed to Hg with ad libitum food over 3 years. We found large (>50 %) reductions in great egret offspring with high Hg exposure (18 mug/g dw THg nestling feather, ~0.7 mug/g ww whole egg THg) and high food availability, and even larger reductions (up to 100 %) with high Hg exposure and low food. Timing and the relative contribution of different endpoints to overall reproductive failure varied with food availability. Failures prior to egg laying were relevant at all food availabilities and proportionally most important during high food availability (~70 % of total losses). Under high food, post-hatching failures increased moderately with increasing exposure (~10 % of total losses), and under low food, hatching failures became dominant (~50 % of total losses). Patterns of failure of captive white ibis fed ad libitum resembled those of great egrets under high food availability but differed in total magnitude. We suggest that, a) net reproductive effects of Hg in free-ranging animals are probably much higher than generally reported in studies using single endpoints, b) Hg effect sizes vary considerably among different endpoints and c) food availability is a strong driver of timing and net effects of Hg exposure.This work was supported by the U.S. Army Corps of Engineers (W912HZ-12-02-0007) and by grants of equipment from the University of Florida Institute of Food and Agricultural Sciences. Egret monitoring was performed under University of Florida IACUC permit 201708650. Fish sampling was supported by Cooperative Agreements W912HZ-11-2-0048 and W912HZ-16-2-0008 between Florida International University (FIU) and the U. S. Army Corps of Engineers and Contract 4600001083 between FIU and the South Florida Water Management District. Fish monitoring was performed under FIU IACUC permits including IACUC-08-004, -09-029, -10-026, 12-020, -13-060, and -16-033. Nestling ibises were collected from the field under Florida Fish and Wildlife Conservation Commission permit WX03527, which also allowed for their maintenance in captivity, and with a modification, re-release into the wild. Ibises were held in captivity under Institutional Animal Care and Use Committee permit D424-2006. Great egret picture in Fig. 1 was taken by J. A. Gonzalez-Oreja and used with his permission while the White Ibis image in the same figure was extracted from a picture downloaded from www.all-free-photos.com licensed under CC BY-SA 2.5. We are grateful to two anonymous reviewers whose comments greatly improved the ms

    A Mainly Circum-Mediterranean Origin for West Eurasian and North African mtDNAs in Puerto Rico with Strong Contributions from the Canary Islands and West Africa

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    Maternal lineages of West Eurasian and North African origin account for 11.5% of total mitochondrial ancestry in Puerto Rico. Historical sources suggest that this ancestry arrived mostly from European migrations that took place during the four centuries of the Spanish colonization of Puerto Rico. This study analyzed 101 mitochondrial control region sequences and diagnostic coding region variants from a sample set randomly and systematically selected using a census-based sampling frame to be representative of the Puerto Rican population, with the goal of defining West Eurasian-North African maternal clades and estimating their possible geographical origin. Median-joining haplotype networks were constructed using HVR-I and –II sequences from various reference populations in search of shared haplotypes. A posterior probability analysis was performed to estimate the percentage of possible origins across wide geographic regions for the entire sample set and for the most common haplogroups on the island. Principal component analyses were conducted to place the Puerto Rican mtDNA set within the variation present amongst all reference populations. Our study shows that up to 38% of West Eurasian and North African mitochondrial ancestry in Puerto Rico most likely migrated from the Canary Islands. However, most of those haplotypes had previously migrated to the Canary Islands from elsewhere, and there are substantial contributions from various populations across the circum-Mediterranean region and from West African populations related to the modern Wolof and Serer peoples from Senegal and the nomad Fulani who extend up to Cameroon. In conclusion, the West Eurasian mitochondrial ancestry in Puerto Ricans is geographically diverse. However, haplotype diversity seems to be low and frequencies have been shaped by population bottlenecks, migration waves, and random genetic drift. Consequently, approximately 47% of mtDNAs of West Eurasian and North African ancestry in Puerto Rico probably arrived early in its colonial history

    Measuring the effectiveness of a WhatsApp course against disinformation for the Elderly in Spain

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    According to the ‘1st Study on Disinformation in Spain 2022’, 95.8% of the population identifies disinformation as a social problem; 91% believe that it could endanger a fair democracy and even the stability of a country. There have been many initiatives designed to tackle the effects of disinformation on individuals and on society, with a special focus on younger generations, due to their significant vulnerability. Elderly people, generally more mature and with a built critical thinking, frequently lack knowledge or abilities to select and weigh all the information the Internet provides. This is especially relevant when that information arrives through second generation networks like WhatsApp. The “How to detect false information online?” course, launched in Spain in the spring of 2022, aimed to fight disinformation and was specially targeted to people of over 50 years of age. The project was developed by Poynter/MediaWise, Newtral and Universidad de Navarra, with the support of Meta. This research, developed by Universidad de Navarra for Poynter/MediaWise, with Meta’s support, assesses the effectiveness of such course when it comes to improving the digital skills of elderly users, taking diverse social, demographic and technologyknowledge elements into account

    Geometry Effects at Atomic-Size Aluminium Contacts

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    We present electronic structure calculations for aluminium nanocontacts. Addressing the neck of the contact, we compare characteristic geometries to investigate the effects of the local aluminium coordination on the electronic states. We find that the Al 3pz states are very sensitive against modifications of the orbital overlap, which has serious consequences for the transport properties. Stretching of the contact shifts states towards the Fermi energy, leaving the system instable against ferromagnetic ordering. By spacial restriction, hybridization is locally suppressed at nanocontacts and the charge neutrality is violated. We discuss the influence of mechanical stress by means of quantitative results for the charge transfer.Comment: 10 pages, 4 figures, accepted by Chem. Phys. Let

    Spontaneous Magnetization and Electron Momentum Density in 3D Quantum Dots

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    We discuss an exactly solvable model Hamiltonian for describing the interacting electron gas in a quantum dot. Results for a spherical square well confining potential are presented. The ground state is found to exhibit striking oscillations in spin polarization with dot radius at a fixed electron density. These oscillations are shown to induce characteristic signatures in the momentum density of the electron gas, providing a novel route for direct experimental observation of the dot magnetization via spectroscopies sensitive to the electron momentum density.Comment: 5 pages (Revtex4), 4 (eps) figure

    Modelling the Effect of Maize Silage and Winter Oat Forage Crop on Cow-Calf Systems in Argentina

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    Cow-calf systems in the flooding Pampa - Argentina, are facing increasing competition with cropping systems for resources and land. In this context, to be more competitive livestock systems require system intensification, which demands an improvement on the feedbase. Forage crops and feeding silage have been used widely on dairy and beef cattle finishing systems. The purpose of the study was to assess with a model the level of intensification that can be achieved in cow calf systems and its economic effects by incorporating maize silage and winter grazing oat crops
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