1,911 research outputs found
Several new forms of Glossopteris fructifications from the Beaufort Daptocephalus-Zone (Upper Permian) of Natal, South Africa
Main articleFertile material, consisting of 27 specimens showing 29 fructifications from Mooi River and 46 specimens showing 98 fructifications from the Loskop site, is described. An emended generic diagnosis of Dictyopteridium is given; specimens belonging to D.sporiferum Feistmantel and D. flabellatum sp. nov. are described, as well as Fetura gen. nov. including F. natalensis comb. nov. and Scopus gen. nov. containing S. gibbosus, S. confertus, S. didiscus and S. obscurus spp. nov.Non
Ancient pigs reveal a near-complete genomic turnover following their introduction to Europe
Archaeological evidence indicates that pig domestication had begun by ∼10,500 y before the present (BP) in the Near East, and mitochondrial DNA (mtDNA) suggests that pigs arrived in Europe alongside farmers ∼8,500 y BP. A few thousand years after the introduction of Near Eastern pigs into Europe, however, their characteristic mtDNA signature disappeared and was replaced by haplotypes associated with European wild boars. This turnover could be accounted for by substantial gene flow from local European wild boars, although it is also possible that European wild boars were domesticated independently without any genetic contribution from the Near East. To test these hypotheses, we obtained mtDNA sequences from 2,099 modern and ancient pig samples and 63 nuclear ancient genomes from Near Eastern and European pigs. Our analyses revealed that European domestic pigs dating from 7,100 to 6,000 y BP possessed both Near Eastern and European nuclear ancestry, while later pigs possessed no more than 4% Near Eastern ancestry, indicating that gene flow from European wild boars resulted in a near-complete disappearance of Near East ancestry. In addition, we demonstrate that a variant at a locus encoding black coat color likely originated in the Near East and persisted in European pigs. Altogether, our results indicate that while pigs were not independently domesticated in Europe, the vast majority of human-mediated selection over the past 5,000 y focused on the genomic fraction derived from the European wild boars, and not on the fraction that was selected by early Neolithic farmers over the first 2,500 y of the domestication process
Natural and human-driven selection of a single non-coding body size variant in ancient and modern canids
Domestic dogs (Canis lupus familiaris) are the most variable-sized mammalian species on Earth, displaying a 40-fold size difference between breeds.1 Although dogs of variable size are found in the archeological record,2, 3, 4 the most dramatic shifts in body size are the result of selection over the last two centuries, as dog breeders selected and propagated phenotypic extremes within closed breeding populations.5 Analyses of over 200 domestic breeds have identified approximately 20 body size genes regulating insulin processing, fatty acid metabolism, TGFβ signaling, and skeletal formation.6, 7, 8, 9, 10 Of these, insulin-like growth factor 1 (IGF1) predominates, controlling approximately 15% of body size variation between breeds.8 The identification of a functional mutation associated with IGF1 has thus far proven elusive.6,10,11 Here, to identify and elucidate the role of an ancestral IGF1 allele in the propagation of modern canids, we analyzed 1,431 genome sequences from 13 species, including both ancient and modern canids, thus allowing us to define the evolutionary history of both ancestral and derived alleles at this locus. We identified a single variant in an antisense long non-coding RNA (IGF1-AS) that interacts with the IGF1 gene, creating a duplex. While the derived mutation predominates in both modern gray wolves and large domestic breeds, the ancestral allele, which predisposes to small size, was common in small-sized breeds and smaller wild canids. Our analyses demonstrate that this major regulator of canid body size nearly vanished in Pleistocene wolves, before its recent resurgence resulting from human-imposed selection for small-sized breed dogs
Audio-description reloaded : an analysis of visual scenes in 2012 and Hero
This article explores whether the so-called new "cinema of attractions", with its supposed focus on visual effects to the detriment of storytelling, requires a specific approach to audio-description (AD). After some thoughts on film narrative in this type of cinema and the way in which it incorporates special effects, selected scenes with AD from two feature films, 2012 (directed by Emmerich) and Hero (directed by Zhang Yimou), are analysed. 2012 is a disaster movie aiming to thrill the audience with action. Hero is an equally visual movie but its imagery has an aesthetic purpose. The analysis investigates how space, time and action are treated in the films and the ADs, and how the information is presented in terms of focalization, timing and phrasing. The results suggest that effect-driven narratives require carefully timed and phrased ADs that devote much attention to the prosody of the AD script, its interaction with sounds and the use of metapho
Grey wolf genomic history reveals a dual ancestry of dogs
The grey wolf (Canis lupus) was the frst species to give rise to a domestic population,
and they remained widespread throughout the last Ice Age when many other large
mammal species went extinct. Little is known, however, about the history and
possible extinction of past wolf populations or when and where the wolf progenitors
of the present-day dog lineage (Canis familiaris) lived1–8
. Here we analysed 72 ancient
wolf genomes spanning the last 100,000 years from Europe, Siberia and North
America. We found that wolf populations were highly connected throughout the Late
Pleistocene, with levels of diferentiation an order of magnitude lower than they are
today. This population connectivity allowed us to detect natural selection across the
time series, including rapid fxation of mutations in the gene IFT88 40,000–30,000
years ago. We show that dogs are overall more closely related to ancient wolves from
eastern Eurasia than to those from western Eurasia, suggesting a domestication
process in the east. However, we also found that dogs in the Near East and Africa
derive up to half of their ancestry from a distinct population related to modern
southwest Eurasian wolves, refecting either an independent domestication process
or admixture from local wolves. None of the analysed ancient wolf genomes is a direct
match for either of these dog ancestries, meaning that the exact progenitor
populations remain to be located
Grey wolf genomic history reveals a dual ancestry of dogs
The grey wolf (Canis lupus) was the first species to give rise to a domestic population, and they remained widespread throughout the last Ice Age when many other large mammal species went extinct. Little is known, however, about the history and possible extinction of past wolf populations or when and where the wolf progenitors of the present-day dog lineage (Canisfamiliaris) lived(1-8). Here we analysed 72 ancient wolf genomes spanning the last 100,000 years from Europe, Siberia and North America. We found that wolf populations were highly connected throughout the Late Pleistocene, with levels of differentiation an order of magnitude lower than they are today. This population connectivity allowed us to detect natural selection across the time series, including rapid fixation of mutations in the gene IFT8840,000-30,000 years ago. We show that dogs are overall more closely related to ancient wolves from eastern Eurasia than to those from western Eurasia, suggesting a domestication process in the east. However, we also found that dogs in the Near East and Africa derive up to half of their ancestry from a distinct population related to modern southwest Eurasian wolves, reflecting either an independent domestication process or admixture from local wolves. None of the analysed ancient wolf genomes is a direct match for either of these dog ancestries, meaning that the exact progenitor populations remain to be located.Peer reviewe
Development and validation of HERWIG 7 tunes from CMS underlying-event measurements
This paper presents new sets of parameters (“tunes”) for the underlying-event model of the HERWIG7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in HERWIG7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at s=0.9, 7, and 13Te. The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the dat
Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at √s = 13 TeV
A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb−1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level
- …
