5,664 research outputs found
Ancient pigs reveal a near-complete genomic turnover following their introduction to Europe
Archaeological evidence indicates that pig domestication had begun by âŒ10,500 y before the present (BP) in the Near East, and mitochondrial DNA (mtDNA) suggests that pigs arrived in Europe alongside farmers âŒ8,500 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
Tracing the first steps of American sturgeon pioneers in Europe
Background: A Baltic population of Atlantic sturgeon was founded ~1,200 years ago by migrants from North America, but after centuries of persistence, the population was extirpated in the 1960s, mainly as a result of over-harvest and habitat alterations. As there are four genetically distinct groups of Atlantic sturgeon inhabiting North American rivers today, we investigated the genetic provenance of the historic Baltic population by ancient DNA analyses using mitochondrial and nuclear markers.
Results: The phylogeographic signal obtained from multilocus microsatellite DNA genotypes and mitochondrial DNA control region haplotypes, when compared to existing baseline datasets from extant populations, allowed for the identification of the region-of-origin of the North American Atlantic sturgeon founders. Moreover, statistical and simulation analyses of the multilocus genotypes allowed for the calculation of the effective number of individuals that originally founded the European population of Atlantic sturgeon. Our findings suggest that the Baltic population of A. oxyrinchus descended from a relatively small number of founders originating from the northern extent of the species' range in North America.
Conclusion: These results demonstrate that the most northerly distributed North American A. oxyrinchus colonized the Baltic Sea ~1,200 years ago, suggesting that Canadian specimens should be the primary source of broodstock used for restoration in Baltic rivers. This study illustrates the great potential of patterns obtained from ancient DNA to identify population-of-origin to investigate historic genotype structure of extinct populations
Limiting fragmentation from scale-invariant merging of fast partons
Exploiting the idea that the fast partons of an energetic projectile can be
treated as sources of color radiation interpreted as wee partons, it is shown
that the recently observed property of extended limiting fragmentation implies
a scaling law for the rapidity distribution of fast partons. This leads to a
picture of a self-similar process where, for fixed total rapidity Y, the
sources merge with probability varying as 1/y.Comment: 10 pages, 1 figure (2 eps files). Final version, also updated w.r.t.
the published version in Phys. Lett. B665/1 (2008) pp. 35-3
Changing conversation and dialogue through LeadSA: an example of public relations activism in South Africa
Abstract:The words of Lund and Nabavi âwe learn more about something if we talk about itâ (2008, p. 27) highlight the importance of conversation and dialogue in bringing about change â be it in an organization or in society. In South Africa, given the countryâs history, dialogue across ethnic, social and political divides does not come naturally. The need for changed and new conversations exists in South Africa. Despite celebrating 20 years of democracy South Africans still face many economic, social and moral challenges. These challenges manifest themselves through protest actions against the slow pace of improvement in the townships, frustration with lack of personal progress among young South Africans, a lack of tolerance and understanding of the âothersâ (Seekings, 2007). Unfortunately change takes time and concerted effort (Eyre & Littleton, 2013), trust must be built and is earned through participation in open dialogue and mutual negotiation (Bardhan, 2011, p. 97). Public relations activism as a manifestation of the postmodernist worldview and PR activists as change agents are at the heart of this exploratory study of the role of public relations in the South African society. The research aim of this article is to investigate the principles and methods used by Primedia Broadcasting South Africaâs LeadSA initiative to start and facilitate social dialogue and to contribute to social change. Data was collected by means of interviews with key decision-makers at LeadSA. In addition, a variety of documents, such as electronic newsletters, internal documents and research reports, were analysed. A case study approach was used to contextualise the theory and illustrate the principles and practices implemented by LeadSA
Bulk Dynamics in Heavy Ion Collisions
The features of heavy ion collisions that suggest the relevance of collective
dynamics, as opposed to mere superpositions of nucleon-nucleon or even
parton-parton collisions, are reviewed. The surprise of these studies is that
bulk observables are far simpler than typical dynamical models of
nucleus-nucleus collisions would imply. These features are shown to have a
natural interpretation in terms of statistical-hydrodynamical models. The
relevance of hydrodynamics to heavy ion collisions, coupled with the various
similarities of the heavy ion data with that of more elementary collisions,
raises very basic questions about its relevance to smaller systems.Comment: 10 Pages, 13 Figures, invited parallel talk at the International
Nuclear Physics Conference (INPC 2004), Goteborg, Sweden, June 27 - July 2,
200
Superposition effect and clan structure in forward-backward multiplicity correlations
The main purpose of this paper is to discuss the link between
forward-backward multiplicity correlations properties and the shape of the
corresponding final charged particle multiplicity distribution in various
classes of events in different collisions. It is shown that the same mechanism
which explains the shoulder effect and the H_n vs. n oscillations in charged
particle multiplicity distributions, i.e., the weighted superposition of
different classes of events with negative binomial properties, reproduces
within experimental errors also the forward-backward multiplicity correlation
strength in e+e- annihilation at LEP energy and allows interesting predictions
for pp collisions in the TeV energy region, to be tested at LHC, for instance
with the ALICE detector. We limit ourselves at present to study substructures
properties in hadron-hadron collisions and e+e- annihilation; they are examined
as ancillary examples in the conviction that their understanding might be
relevant also in other more complex cases.Comment: 16 page
Jet Energy Density in Hadron-Hadron Collisions at High Energies
The average particle multiplicity density dN/deta is the dynamical quantity
which reflects some regularities of particle production in low-pT range. The
quantity is an important ingredient of z-scaling. Experimental results on
charged particle density are available for pp, pA and AA collisions while
experimental properties of the jet density are still an open question. The goal
of this work is to find the variable which will reflect the main features of
the jet production in low transverse energy range and play the role of the
scale factor for the scaling function psi(z) and variable z in data
z-presentation. The appropriate candidate is the variable we called "scaled jet
energy density". Scaled jet energy density is the probability to have a jet
with defined ET in defined xT and pseudorapidity regions. The PYTHIA6.2 Monte
Carlo generator is used for calculation of scaled jet energy density in
proton-proton collisions over a high energy range (sqrt s = 200-14000 GeV) and
at eta = 0. The properties of the new variable are discussed and sensitivity to
"physical scenarios" applied in the standard Monte Carlo generator is noted.
The results of scaled jet energy density at LHC energies are presented and
compared with predictions based on z-scaling.Comment: 11 pages, LaTeX, 8 figures, Presented at the XVII International
Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics
& Quantum Chromodynamics", Dubna, Russia, September 27 - October 2, 200
The longitudinal phase-space integral with leading particles
De Grootâs method of calculating the longitudinal phase-space integrals is generalized to include leading particles. The generalization simplifies practical calculations of all quantities predicted by the uncorrelated jet model with leading particles
Scavenging in Northwestern Europe: A Survey of UK Police Specialist Search Officers
Physical search methods used by police specialist searchers
are based on counter-terrorism methods and not on the search and recovery of outdoor surface deposited human remains, nevertheless these methods are applied to scenes
involving human remains. Additionally, there is limited published forensic literature within Northwestern Europe on the potential taphonomic agents within this region that are capable of modifying human remains through scavenging, scattering and removal. The counter-terrorism basis in physical search methods and the gap in published forensic literature regarding scavenging in this region can potentially impede searchersâ abilities to adapt physical
search methods to their full efficiency in the search and recovery of scavenged human remains. This paper analysed through a questionnaire survey of 111 police specialist searchers, within the U.K., the impact of animal scavenging on the search and recovery of human remains.According to
questionnaire respondentsâ experiences and knowledge, the occurrence of scavenging at scenes in which respondents took part in a physical search for human remains was common
(63.46%,n= 66) and happened most frequently with surface deposits (68.25%,n= 43). Scavenging resulted in the recovery of incomplete sets of remains (59.79%, n= 58) and
influenced search perimeters (58.33%, n= 35). Scavenging also affected recovery rates at scene searches (80.43%,n= 74) that included the use of cadaver dogs with police handlers. The impact scavengers within this region have on different crime scene scenarios and search methods is not reflected in current published literature or search standards
Effects of Repeated Intrathecal Triamcinolone-Acetonide Application on Cerebrospinal Fluid Biomarkers of Axonal Damage and Glial Activity in Multiple Sclerosis Patients
Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system in young adults. Over time, the disease progresses and, with accumulating disability, symptoms such as spasticity may occur. Although several treatment options are available, some patients may not respond to first-line therapeutics. However, some of these patients may benefit from intrathecally administered triamcinolone-acetonide (TCA), a derivative of glucocorticosteroids (GCS).GCSmay have neurotoxic effects, and cell apoptosis may occur. The aim of this study was to investigate the effects of TCA on biomarkers in the cerebrospinal fluid (CSF) suggestive of neurodegeneration
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