453 research outputs found
Properties of a new quasi-axisymmetric configuration
A novel, compact, quasi-axisymmetric configuration is presented which
exhibits low fast-particle losses and is stable to ideal MHD instabilities. The
design has fast-particle loss rates below 8\% for flux surfaces within the
half-radius, and is shown to have an MHD-stability limit of a normalised
pressure of where is volume
averaged. The flux surfaces at various plasma betas and currents as calculated
using the SPEC equilibrium code are presented. Neoclassical transport
coefficients are shown to be similar to an equivalent tokamak, with a distinct
banana regime at half-radius. An initial coil design study is presented to
assess the feasibility of this configuration as a fusion-relevant experiment
Critical gradient turbulence optimization toward a compact stellarator reactor concept
Integrating turbulence into stellarator optimization is shown by targeting
the onset for the ion-temperature-gradient mode, highlighting effects of
parallel connection length, local magnetic shear, and flux surface expansion.
The result is a compact quasihelically symmetric stellarator configuration,
admitting a set of uncomplicated coils, with significantly reduced turbulent
heat fluxes compared to a known stellarator. The new configuration combines low
values of neoclassical transport, good alpha particle confinement, and Mercier
stability at a plasma beta of almost 2.Comment: 5 pages, 5 figures. Phys. Rev. Research 5, L032030 (2023
New perspectives on evolutionary medicine: the relevance of microevolution for human health and disease
Evolutionary medicine (EM) is a growing field focusing on the evolutionary basis of human diseases and their changes through time. To date, the majority of EM studies have used pure theories of hominin macroevolution to explain the present-day state of human health. Here, we propose a different approach by addressing more empirical and health-oriented research concerning past, current and future microevolutionary changes of human structure, functions and pathologies. Studying generation-to-generation changes of human morphology that occurred in historical times, and still occur in present-day populations under the forces of evolution, helps to explain medical conditions and warns clinicians that their current practices may influence future humans. Also, analyzing historic tissue specimens such as mummies is crucial in order to address the molecular evolution of pathogens, of the human genome, and their coadaptations.Frank Jakobus RĂŒhli and Maciej Henneber
Energetic particle transport in optimized stellarators
Nine stellarator configurations, three quasiaxisymmetric, three
quasihelically symmetric and three non-quasisymmetric are scaled to ARIES-CS
size and analyzed for energetic particle content. The best performing
configurations with regard to energetic particle confinement also perform the
best on the neoclassical {\Gamma}c metric, which attempts to align contours of
the second adiabatic invariant with flux surfaces. Quasisymmetric
configurations that simultaneously perform well on {\Gamma}c and quasisymmetry
have the best overall confinement, with collisional losses under 3%,
approaching the performance of ITER with ferritic inserts.Comment: 18 pages, 10 figures, 1 Tabl
Assessing plant diversity and composition in grasslands across spatial scales: the standardised EDGG sampling methodology
This paper presents the details of the EDGG sampling methodology and its underlying rationales. The methodology has been applied during EDGG Research Expeditions and EDGG Field Workshops since 2009, and has been subsequently adopted by various other researchers. The core of the sampling are the EDGG Biodiversity Plots, which are 100âm2 squares comprising, in two opposite corners, nestedâplot series of 0.0001, 0.001, 0.01, 0.1, 1 and 10 m2 square plots, in which all terricolous vascular plants, bryophytes and lichens are recorded using the shoot presence method. In the 10âm2 plots, species cover is also estimated as a percentage and various environmental and structural parameters are recorded. Usually the EDGG Biodiversity Plots are complemented by the sampling of additional 10 m2 normal plots with the same parameters as the 10âm2 corners of the first, allowing coverage of a greater environmental diversity and the achievement of higher statistical power in the subsequent analyses for this important grain size. The EDGG sampling methodology has been refined over the years, while its core has turned out to generate highâquality, standardised data in an effective manner, which facilitates a multitude of analyses. In this paper we provide the current versions of our guidelines, field forms and data entry spreadsheets, as openâaccess Online Resources to facilitate the easy implementation of this methodology by other researchers. We also discuss potential future additions and modifications to the approach, among which the most promising are the use of stratifiedârandom methods to a priori localise the plots and ideas to sample invertebrate taxa on the same plots and grain sizes, such as grasshoppers (Orthoptera) and vegetationâdwelling spiders (Araneae). As with any other method, the EDGG sampling methodology is not ideal for every single purpose, but with its continuous improvements and its flexibility, it is a good multiâ purpose approach. A particularly advantageous element, lacking in most other sampling schemes, including classical phytosociogical sampling, is the multiâscale and multiâtaxon approach, which provides data that allow for deeper understanding of the generalities and idiosyncrasies of biodiversity patterns and their underlying drivers across scales and taxa
Health effects of European colonization: An investigation of skeletal remains from 19th to early 20th century migrant settlers in South Australia
The British colony of South Australia, established in 1836, offered a fresh start to migrants hoping for a better life. A cohort of settlers buried in a section of St Maryâs Anglican Church Cemetery (1847â1927) allocated for government funded burials was investigated to determine their health, with a focus on skeletal manifestations associated with metabolic deficiencies. Findings of St Maryâs sample were compared with those published for contemporary skeletal samples from two British cemeteries, St Martinâs, Birmingham, and St Peterâs, Wolverhampton, to explore similarities and differences. To investigate the changing economic background of the St Maryâs cohort, which may have influenced the location of their burial within the cemetery, the number and demographic profile of government funded burials and those in privately funded leased plots were compared. The study sample consisted of the skeletal remains of 65 individuals (20 adults, 45 subadults) from St Maryâs Cemetery âfree groundâ section. The bones and teeth of individuals in this cohort showed evidence of pathological manifestations, including areas of abnormal porosity in bone cortices in 9 adults and 12 subadults and flaring of metaphyses (one subadult) and costochondral junctions of the ribs (one subadult). Porous lesions of orbital roof bones (Types 3 to 4) were seen on three subadults. Macroscopic examination of teeth identified enamel hypoplastic defects and micro-CT scans showed areas of interglobular dentine. Comparison of St Maryâs findings with the British samples revealed that prevalences of manifestations associated with vitamin C deficiency were higher at St Maryâs and manifestations associated with vitamin D deficiency were lower respectively. The location of burial pattern at St Maryâs Cemetery, from the mid-1840s to1860s, showed differences in the economic status of migrants. This pattern changed from the 1870s, which reflected improvements in the local economy and the economic recovery of the colony.Angela Gurr, Jaliya Kumaratilake, Alan Henry Brook, Stella Ioannou, F. Donald Pate, Maciej Henneber
Queen Nefertari, the royal spouse of pharaoh Ramses II: a multidisciplinary investigation of the mummified remains found in her tomb (QV66)
Queen Nefertari, the favourite Royal Consort of Pharaoh Ramses II (Ancient Egypt, New Kingdom, 19th Dynasty c. 1250 BC) is famous for her beautifully decorated tomb in the Valley of the Queens. Her burial was plundered in ancient times yet still many objects were found broken in the debris when the tomb was excavated. Amongst the found objects was a pair of mummified legs. They came to the Egyptian Museum in Turin and are henceforth regarded as the remains of this famous Queen, although they were never scientifically investigated. The following multidisciplinary investigation is the first ever performed on those remains. The results (radiocarbon dating, anthropology, paleopathology, genetics, chemistry and Egyptology) all strongly speak in favour of an identification of the remains as Nefertari's, although different explanations-albeit less likely-are considered and discussed. The legs probably belong to a lady, a fully adult individual, of about 40 years of age. The materials used for embalming are consistent with Ramesside mummification traditions and indeed all objects within the tomb robustly support the burial as of Queen Nefertari.Michael E. Habicht, Raffaella Bianucci, Stephen A. Buckley, Joann Fletcher, Abigail S. Bouwman, Lena M. Ćhrström, Roger Seiler, Francesco M. Galassi, Irka Hajdas, Eleni Vassilika, Thomas Böni, Maciej Henneberg, Frank J. RĂŒhl
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