172 research outputs found
Spin-Orbit-Induced Orbital Excitations in Sr2RuO4 and Ca2RuO4: A Resonant Inelastic X-ray Scattering Study
High-resolution resonant inelastic X-ray scattering (RIXS) at the oxygen
K-edge has been used to study the orbital excitations of Ca2RuO4 and Sr2RuO4.
In combination with linear dichroism X-ray absorption spectroscopy, the
ruthenium 4d-orbital occupation and excitations were probed through their
hybridization with the oxygen p-orbitals. These results are described within a
minimal model, taking into account crystal field splitting and a spin-orbit
coupling \lambda_{so}=200~meV. The effects of spin-orbit interaction on the
electronic structure and implications for the Mott and superconducting ground
states of (Ca,Sr)2RuO4 are discussed.Comment: accepted in PRB 201
Assessing vegetable oils and extracts for the control of Sitophilus zeamaiz and its impact on the seed quality of corn
Sitophilus zeamaiz es una de las especies
de gorgojos que más pérdidas causa en granos
almacenados en el mundo; su control se basa
principalmente en productos sintéticos, que con
el paso del tiempo resultan menos efectivos.
En la presente investigación se evaluaron
aceites vegetales de ricino, soya y extractos
vegetales de neem y lila sobre poblaciones de
S. zeamaiz y sus efectos sobre la germinación
y parámetros fisiológicos de las plántulas. Los
resultados muestran que el aceite de soya dio
los mejores resultados de control, al presentar
mortalidades entre un 92 y 100% a las 192
horas. Sin embargo, este aceite afecta la
germinación a dosis de 2000 a 10000 ppm. El
extracto de neem presentó mortalidades del
78,75 y 91,25% a las 192 horas, sin afectar la
germinación ni las propiedades agronómicas.
Finalmente, el aceite de ricino y el extracto de
lila fueron los tratamientos que, para las condiciones
del presente estudio, no mostraron altas
mortalidades sobre S. zeamaiz.Sitophilus zeamaiz is one of the most
damaging weevil species of stored grains in
the world and a major cause of devastating
losses. Its control is mainly based on synthetic
products that are every day less effective. The
current research work assessed the effects
of castor oil, soybean oil; Neem and lily plant
extracts on S. zeamaiz populations and their
impact upon germination and physiological
parameters of seedlings. Results have shown
that soybean oil yielded the best control
results, with mortality rates between 92 and
100% after 192 hours of the application.
Nevertheless, soybean oil affects germination
at 2000 - 10000 ppm rates. Neem extract
reached mortality rates of 78.75 and 91.25%
at 192 hours, with no impact on germination
and agronomic properties. Finally, castor oil
and lily extract did not yield high mortality rates
over S. zeamaiz.Fil: Cerna Chávez, Ernesto.
Universidad Autónoma Agraria Antonio Narro (México). Departamento de Parasitología AgrícolaFil: Landeros Flores, Jerónimo.
Universidad Autónoma Agraria Antonio Narro (México). Departamento de Parasitología AgrícolaFil: Ochoa Fuentes, Yisa María.
Universidad Autónoma de Aguascalientes (México). Centro de Ciencias AgropecuariasFil: Guevara Acevedo, Luis.
Universidad Autónoma Agraria Antonio Narro (México). Departamento de Parasitología AgrícolaFil: Badii Zabeth, Mohammad H..
Universidad Autónoma de Nuevo León (México). Facultad de Ciencias BiológicasFil: Olalde Portugal, Víctor.
Instituto Politécnico Nacional (México). Centro de Investigación y de Estudios Avanzados. Laboratorio de Bioquímica Ecológic
Evidence for weak electronic correlations in Fe-pnictides
Using x-ray absorption and resonant inelastic x-ray scattering, charge
dynamics at and near the Fe edges is investigated in Fe pnictide materials,
and contrasted to that measured in other Fe compounds. It is shown that the XAS
and RIXS spectra for 122 and 1111 Fe pnictides are each qualitatively similar
to Fe metal. Cluster diagonalization, multiplet, and density-functional
calculations show that Coulomb correlations are much smaller than in the
cuprates, highlighting the role of Fe metallicity and strong covalency in these
materials. Best agreement with experiment is obtained using Hubbard parameters
eV and eV.Comment: 11 pages, 12 figure
Compositional Evolution of Individual CoNPs on Co/TiO2 during CO and Syngas Treatment Resolved through Soft XAS/X-PEEM
The nanoparticle (NP) redox state is an important parameter in the performance of cobalt-based Fischer-Tropsch synthesis (FTS) catalysts. Here, the compositional evolution of individual CoNPs (6-24 nm) in terms of the oxide vs metallic state was investigated in situ during CO/syngas treatment using spatially resolved X-ray absorption spectroscopy (XAS)/X-ray photoemission electron microscopy (X-PEEM). It was observed that in the presence of CO, smaller CoNPs (i.e., ≤12 nm in size) remained in the metallic state, whereas NPs ≥ 15 nm became partially oxidized, suggesting that the latter were more readily able to dissociate CO. In contrast, in the presence of syngas, the oxide content of NPs ≥ 15 nm reduced, while it increased in quantity in the smaller NPs; this reoxidation that occurs primarily at the surface proved to be temporary, reforming the reduced state during subsequent UHV annealing. O K-edge measurements revealed that a key parameter mitigating the redox behavior of the CoNPs were proximate oxygen vacancies (Ovac). These results demonstrate the differences in the reducibility and the reactivity of Co NP size on a Co/TiO2 catalyst and the effect Ovac have on these properties, therefore yielding a better understanding of the physicochemical properties of this popular choice of FTS catalysts
'Ava’: a Beaker-associated woman from a cist at Achavanich, Highland, and the story of her (re-) discovery and subsequent study
This contribution describes the discovery and subsequent investigation of a cist in a rock-cut pit at Achavanich, Highland. Discovered and excavated in 1987, the cist was found to contain the tightly contracted skeletal remains of a young woman, accompanied by a Beaker, three flint artefacts and a cattle scapula. Initial post excavation work established a date for the skeleton together with details of her age and sex, and preliminary pollen analysis of sediments attaching to the Beaker was undertaken. The findings were never fully published and, upon the death of the excavator, Robert Gourlay, the documentary archive was left in the Highland Council Archaeology Unit. Fresh research in 2014–17, initiated and co-ordinated by the first-named author and funded by the Society of Antiquaries of Scotland with assistance from National Museums Scotland, the Natural History Museum and Harvard Medical School, has produced a significant amount of new information on the individual and on some of the items with which she was buried. This new information includes two further radiocarbon dates, a more detailed osteological report, isotopic information pertaining to the place where she had been raised and to her diet, histological information on the decomposition of her body, and genetic information that sheds light on her ancestry, her hair, eye and skin colour and her intolerance of lactose. (This is the first time that an ancient DNA report has been published in the Proceedings.) Moreover, a facial reconstruction adds virtual flesh to her bones. The significance of this discovery within the Chalcolithic to Early Bronze Age of this part of Scotland is discussed, along with the many and innovative ways in which information on this individual, dubbed ‘Ava’, has been disseminated around the world.Copyright © 2018 rests with the Society and the individual authors. Except where otherwise noted, this work is licensed under CreativeCommons Attribution-NonCommercial-No Derivatives licence.https://creativecommons.org/licenses/by-nc-nd/4.0/
The permission to reproduce the Society's copyright-protected ma-terial does not extend to any material which is identified as being the copyright of a third party. Authorisation to reproduce such material must be obtained from the copyright holders concerned. The attached file is the published pdf
Tracing the dynamic life story of a Bronze Age Female
YesAncient human mobility at the individual level is conventionally studied by the diverse application of suitable techniques (e.g. aDNA, radiogenic strontium isotopes, as well as oxygen and lead isotopes) to either hard and/or soft tissues. However, the limited preservation of coexisting hard and soft human tissues hampers the possibilities of investigating high-resolution diachronic mobility periods in the life of a single individual. Here, we present the results of a multidisciplinary study of an exceptionally well preserved circa 3.400-year old Danish Bronze Age female find, known as the Egtved Girl. We applied biomolecular, biochemical and geochemical analyses to reconstruct her mobility and diet. We demonstrate that she originated from a place outside present day Denmark (the island of Bornholm excluded), and that she travelled back and forth over large distances during the final months of her life, while consuming a terrestrial diet with intervals of reduced protein intake. We also provide evidence that all her garments were made of non-locally produced wool. Our study advocates the huge potential of combining biomolecular and biogeochemical provenance tracer analyses to hard and soft tissues of a single ancient individual for the reconstruction of high-resolution human mobility.The Danish National Research Foundation; The Carlsberg Foundation, L'Oreal Denmark-UNESCO; The ERC agreement no. 26944
Massive migration from the steppe is a source for Indo-European languages in Europe
We generated genome-wide data from 69 Europeans who lived between 8,000-3,000
years ago by enriching ancient DNA libraries for a target set of almost four
hundred thousand polymorphisms. Enrichment of these positions decreases the
sequencing required for genome-wide ancient DNA analysis by a median of around
250-fold, allowing us to study an order of magnitude more individuals than
previous studies and to obtain new insights about the past. We show that the
populations of western and far eastern Europe followed opposite trajectories
between 8,000-5,000 years ago. At the beginning of the Neolithic period in
Europe, ~8,000-7,000 years ago, closely related groups of early farmers
appeared in Germany, Hungary, and Spain, different from indigenous
hunter-gatherers, whereas Russia was inhabited by a distinctive population of
hunter-gatherers with high affinity to a ~24,000 year old Siberian6 . By
~6,000-5,000 years ago, a resurgence of hunter-gatherer ancestry had occurred
throughout much of Europe, but in Russia, the Yamnaya steppe herders of this
time were descended not only from the preceding eastern European
hunter-gatherers, but from a population of Near Eastern ancestry. Western and
Eastern Europe came into contact ~4,500 years ago, as the Late Neolithic Corded
Ware people from Germany traced ~3/4 of their ancestry to the Yamnaya,
documenting a massive migration into the heartland of Europe from its eastern
periphery. This steppe ancestry persisted in all sampled central Europeans
until at least ~3,000 years ago, and is ubiquitous in present-day Europeans.
These results provide support for the theory of a steppe origin of at least
some of the Indo-European languages of Europe
Genomic Analyses of Pre-European Conquest Human Remains from the Canary Islands Reveal Close Affinity to Modern North Africans
The origins and genetic affinity of the aboriginal inhabitants of the Canary Islands, commonly known as Guanches, are poorly understood. Though radiocarbon dates on archaeological remains such as charcoal, seeds, and domestic animal bones suggest that people have inhabited the islands since the 5th century BCE, it remains unclear how many times, and by whom, the islands were first settled. Previously published ancient DNA analyses of uniparental genetic markers have shown that the Guanches carried common North African Y chromosome markers (E-M81, E-M78, and J-M267) and mitochondrial lineages such as U6b, in addition to common Eurasian haplogroups. These results are in agreement with some linguistic, archaeological, and anthropological data indicating an origin from a North African Berber-like population. However, to date there are no published Guanche autosomal genomes to help elucidate and directly test this hypothesis. To resolve this, we generated the first genome-wide sequence data and mitochondrial genomes from eleven archaeological Guanche individuals originating from Gran Canaria and Tenerife. Five of the individuals (directly radiocarbon dated to a time transect spanning the 7th–11th centuries CE) yielded sufficient autosomal genome coverage (0.21× to 3.93×) for population genomic analysis. Our results show that the Guanches were genetically similar over time and that they display the greatest genetic affinity to extant Northwest Africans, strongly supporting the hypothesis of a Berber-like origin. We also estimate that the Guanches have contributed 16%–31% autosomal ancestry to modern Canary Islanders, here represented by two individuals from Gran Canaria
‘Ava’: a Beaker-associated woman from a cist at Achavanich, Highland, and the story of her (re-)discovery and subsequent study
This contribution describes the discovery and subsequent investigation of a cist in a rock-cut pit at Achavanich, Highland. Discovered and excavated in 1987, the cist was found to contain the tightly contracted skeletal remains of a young woman, accompanied by a Beaker, three int artefacts and a cattle scapula. Initial post-excavation work established a date for the skeleton together with details of her age and sex, and preliminary pollen analysis of sediments attaching to the Beaker was undertaken. The ndings were never fully published and, upon the death of the excavator, Robert Gourlay, the documentary archive was left in the Highland Council Archaeology Unit. Fresh research in 2014–17, initiated and co-ordinated by the rst-named author and funded by the Society of Antiquaries of Scotland with assistance from National Museums Scotland, the Natural History Museum and Harvard Medical School, has produced a signi cant amount of new information on the individual and on some of the items with which she was buried. This new information includes two further radiocarbon dates, a more detailed osteological report, isotopic information pertaining to the place where she had been raised and to her diet, histological information on the decomposition of her body, and genetic information that sheds light on her ancestry, her hair, eye and skin colour and her intolerance of lactose. (This is the rst time that an ancient DNA report has been published in the Proceedings.) Moreover, a facial reconstruction adds virtual esh to her bones. The signi cance of this discovery within the Chalcolithic to Early Bronze Age of this part of Scotland is discussed, along with the many and innovative ways in which information on this individual, dubbed ‘Ava’, has been disseminated around the world
Latitudinal gradient in dairy production with the introduction of farming in Atlantic Europe
International audienceThe introduction of farming had far-reaching impacts on health, social structure and demography. Although the spread of domesticated plants and animals has been extensively tracked, it is unclear how these nascent economies developed within different environmental and cultural settings. Using molecular and isotopic analysis of lipids from pottery, here we investigate the foods prepared by the earliest farming communities of the European Atlantic seaboard. Surprisingly, we find an absence of aquatic foods, including in ceramics from coastal sites, except in the Western Baltic where this tradition continued from indigenous ceramic using hunter-gatherer-fishers. The frequency of dairy products in pottery increased as farming was progressively introduced along a northerly latitudinal gradient. This finding implies that early farming communities needed time to adapt their economic practices before expanding into more northerly areas. Latitudinal differences in the scale of dairy production might also have influenced the evolution of adult lactase persistence across Europe
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