39,677 research outputs found
Rare dental trait provides morphological evidence of archaic introgression in Asian fossil record
The recently described Denisovan hemimandible from Xiahe, China [F. Chen et al., (2019) Nature 569, 409â412], possesses an unusual dental feature: a 3-rooted lower second molar. A survey of the clinical and bioarchaeological literature demonstrates that the 3-rooted lower molar is rare (less than 3.5% occurrence) in non-Asian Homo sapiens. In contrast, its presence in Asian-derived populations can exceed 40% in China and the New World. It has long been thought that the prevalence of 3-rooted lower molars in Asia is a relatively late acquisition occurring well after the origin and dispersal of H. sapiens. However, the presence of a 3-rooted lower second molar in this 160,000-y-old fossil hominin suggests greater antiquity for the trait. Importantly, it also provides morphological evidence of a strong link between archaic and recent Asian H. sapiens populations. This link provides compelling evidence that modern Asian lineages acquired the 3-rooted lower molar via introgression from Denisovans
The tartan tax versus other revenue-raising options
Much has already been written about the devolved Scottish Parliament's Tartan Tax-varying powers (for example Blow et al. 1996, Darby et al. 2002, Heald and Geaughan 1996 and 1999, Heald et al. 1998, Heald and McLeod 2002, McGregor et al. 1997, Midwinter 2002, Muscatelli 2001, SPICe 2002). Much less has been written about other revenue raising options and it is the contention of this paper that the focus of attention on Tartan Tax-varying powers has been misplaced
Recommended from our members
Participatory action research in the development and delivery of self-harm awareness sessions in prison: involving service users in staff development
Discovery of secular variations in the atmospheric abundances of magnetic Ap stars
The stars of the middle main sequence have relatively quiescent outer layers,
and unusual chemical abundance patterns may develop in their atmospheres. The
presence of chemical peculiarities reveal the action of such subsurface
phenomena as gravitational settling and radiatively driven levitation of trace
elements, and their competition with mixing processes such as turbulent
diffusion.
We want to establish whether abundance peculiarities change as stars evolve
on the main sequence, and provide observational constraints to diffusion
theory.
We have performed spectral analysis of 15 magnetic Bp stars that are members
of open clusters (and thus have well-known ages), with masses between about 3
and 4 M_sun. For each star, we measured the abundances of He, O, Mg, Si, Ti,
Cr, Fe, Pr and Nd.
We have discovered the systematic time evolution of trace elements through
the main-sequence lifetime of magnetic chemically peculiar stars as their
atmospheres cool and evolve toward lower gravity. During the main sequence
lifetime, we observe clear and systematic variations in the atmospheric
abundances of He, Ti, Cr, Fe, Pr and Nd. For all these elements, except He, the
atmospheric abundances decrease with age. The abundances of Fe-peak elements
converge toward solar values, while the rare-earth elements converge toward
values at least 100 times more abundant than in the Sun. Helium is always
underabundant compared to the Sun, evolving from about 1% up to 10% of the
solar He abundance. We have attempted to interpret the observed abundance
variations in the context of radiatively driven diffusion theory, which appears
to provide a framework to understand some, but not all, of the observed
anomalous abundance levels and variations.Comment: 13 pages, 5 figures, 5 tables, accepted for publication in A&
Oscillating chiral currents in nanotubes: a route to nanoscale magnetic test tubes
With a view to optimising the design of carbon-nanotube (CNT) windmills and
to maximising the internal magnetic field generated by chiral currents, we
present analytical results for the group velocity components of an electron
flux through chiral carbon nanotubes. Chiral currents are shown to exhibit a
rich behaviour and can even change sign and oscillate as the energy of the
electrons is increased. We find that the transverse velocity and associated
angular momentum of electrons is a maximum for non-metallic CNTs with a chiral
angle of 18. Such CNTs are therefore the optimal choice for CNT windmills
and also generate the largest internal magnetic field for a given longitudinal
current. For a longitudinal current of order amps, this field can be
of order Teslas, which is sufficient to produce interesting spintronic
effects and a significant contribution to the self inductance.Comment: 4 pages, 1 figur
Twelve Theses on Reactive Rules for the Web
Reactivity, the ability to detect and react to events, is an
essential functionality in many information systems. In particular, Web
systems such as online marketplaces, adaptive (e.g., recommender) systems,
and Web services, react to events such as Web page updates or
data posted to a server.
This article investigates issues of relevance in designing high-level programming
languages dedicated to reactivity on the Web. It presents
twelve theses on features desirable for a language of reactive rules tuned
to programming Web and Semantic Web applications
Near-IR Spectropolarimetry of NGC 1088
Original paper can be found at: http://www.astrosociety.org/pubs/cs/035-069.html--Copyright Astronomical Society of the PacificThe current unified model of Seyfert galaxies, as proposed by Antonucci and Miller (1985), has most, if not all, Seyfert 2 galaxies hosting a Seyfert 1 type nucleus in their cores. The broad lines from the type 1 nucleus can be scattered and be seen in the polarized flux spectrum, provided the geometry is correct. Whether the mechanism is electron or dust scattering has been a question of some debate. Since dust would normally have a low scattering efficiency in the infrared, near-IR spectropolarimetry should help in determing the nature of the scatterers. To this end we present the first near-IR spectropolarimetry of NGC 1068 a "Seyfert 2" galaxy in which polarized broad lines have been observed at optical wavelengths
Systematic Review of the Literature on Black and Minority Ethnic Communities in Sport and Physical Recreation
The Carnegie Research Institute was commissioned by Sporting Equals and the Sports Councils to conduct an independent systematic review of the literature on participation in sport and recreation by Black and minority ethnic (BME) communities. The brief was to focus on UK material from the past ten years, to compile an electronic, bibliographic database and use that evidence to assess the policy significance of existing knowledge in the drive to widen and increase participation. Although the field might still be considered under-researched over 300 items were identified. Judgements were made on the quality of the research on the basis of the methodological and theoretical soundness and the credibility of the link between the conclusions and the data. The various items were collated in an electronic, bibliographic database and coded as: substantive research of good quality; related public statistics and policy documents; and other related materials of interest. The research, policy and practice contained in this body of work is set within an expanding national and international framework of policy and legislation concerned with human rights and principles of equality. The Sports Councils and Sporting Equals have played a significant part in this through initiatives like the Equality Standard. They have not been acting in isolation, but have received support from other sports bodies with initiatives both to challenge discrimination and inequality and to promote participation and inclusion. Nonetheless, there still seems to be a measure of disconnection between research, sports policies and equality policies. Indeed, sports policies are sometimes based on limited representations of racism and so are inhibited in the way they address racial equality
- âŠ