1,324 research outputs found
Photoemission investigation of the electronic structure of Fe-Pd and Fe-Pt alloys
A photoemission investigation of Fe-Pd and Fe-Pt transition-metal alloys, using ∼50–150-eV synchrotron radiation, is presented. We consider in particular the spectral distribution of Fe states when approaching the dilute limit. By means of the Cooper minimum in the 4d and 5d photoionization cross section, we identify structures that have mainly Fe minority- or Fe majority-spin character. The relative position of these peaks is discussed in terms of the covalent interaction between Fe 3d and Pd or Pt d states. Also, the strong resemblance between the distribution of Fe states in the Pd-based and in the Pt-based alloys is demonstrated. We find a consistent behavior of interacting d states towards the dilute limit. It is concluded that the Fe states that are observed in the photoemission spectra of the dilute alloys have mainly majority-spin character and are, because of the covalent interaction with host states, widely distributed over the energy range of the host d band. The Fe minority-spin band, which is centered near the Fermi level, gradually empties with increasing Fe dilution
Three-Body and One-Body Channels of the Auger Core-Valence-Valence decay: Simplified Approach
We propose a computationally simple model of Auger and APECS line shapes from
open-band solids. Part of the intensity comes from the decay of unscreened
core-holes and is obtained by the two-body Green's function ,
as in the case of filled bands. The rest of the intensity arises from screened
core-holes and is derived using a variational description of the relaxed ground
state; this involves the two-holes-one-electron propagator , which
also contains one-hole contributions. For many transition metals, the two-hole
Green's function can be well described by the Ladder
Approximation, but the three-body Green's function poses serious further
problems. To calculate , treating electrons and holes on equal
footing, we propose a practical approach to sum the series to all orders. We
achieve that by formally rewriting the problem in terms of a fictitious
three-body interaction. Our method grants non-negative densities of states,
explains the apparent negative-U behavior of the spectra of early transition
metals and interpolates well between weak and strong coupling, as we
demonstrate by test model calculations.Comment: AMS-LaTeX file, 23 pages, 8 eps and 3 ps figures embedded in the text
with epsfig.sty and float.sty, submitted to Phys. Rev.
Patients' perceptions of the potential of breathing training for asthma: a qualitative study.
Poor symptom control is common in asthma. Breathing training exercises may be an effective adjunct to medication; it is therefore important to understand facilitators and barriers to uptake of breathing training exercises
Facilitating the analysis of COVID-19 literature through a knowledge graph
At the end of 2019, Chinese authorities alerted the World Health Organization (WHO) of the outbreak of a new strain of the coronavirus, called SARS-CoV-2, which struck humanity by an unprecedented disaster a few months later. In response to this pandemic, a publicly available dataset was released on Kaggle which contained information of over 63,000 papers. In order to facilitate the analysis of this large mass of literature, we have created a knowledge graph based on this dataset. Within this knowledge graph, all information of the original dataset is linked together, which makes it easier to search for relevant information. The knowledge graph is also enriched with additional links to appropriate, already existing external resources. In this paper, we elaborate on the different steps performed to construct such a knowledge graph from structured documents. Moreover, we discuss, on a conceptual level, several possible applications and analyses that can be built on top of this knowledge graph. As such, we aim to provide a resource that allows people to more easily build applications that give more insights into the COVID-19 pandemic
Molecular dynamics with coupling to an external bath
In molecular dynamics (MD) simulations the need often arises to maintain such parameters as temperature or pressure rather than energy and volume, or to impose gradients for studying transport properties in nonequilibrium MD. A method is described to realize coupling to an external bath with constant temperature or pressure with adjustable time constants for the coupling. The method is easily extendable to other variables and to gradients, and can be applied also to polyatomic molecules involving internal constraints. The influence of coupling time constants on dynamical variables is evaluated. A leap‐frog algorithm is presented for the general case involving constraints with coupling to both a constant temperature and a constant pressure bath
A linear AC trap for polar molecules in their ground state
Contains fulltext :
98810.pdf (preprint version ) (Open Access
Use of domesticated pigs by Mesolithic hunter-gatherers in northwestern Europe
Acknowledgements We thank the Archaeological State Museum Schleswig-Holstein, the Archaeological State Offices of Brandenburg, Lower Saxony and Saxony and the following individuals who provided sample material: Betty Arndt, Jo¨rg Ewersen, Frederick Feulner, Susanne Hanik, Ru¨diger Krause, Jochen Reinhard, Uwe Reuter, Karl-Heinz Ro¨hrig, Maguerita Scha¨fer, Jo¨rg Schibler, Reinhold Schoon, Regina Smolnik, Thomas Terberger and Ingrid Ulbricht. We are grateful to Ulrich Schmo¨lcke, Michael Forster, Peter Forster and Aikaterini Glykou for their support and comments on the manuscript. We also thank many institutions and individuals that provided sample material and access to collections, especially the curators of the Museum fu¨r Naturkunde, Berlin; Muse´um National d0 Histoire Naturelle, Paris; Smithsonian Institution, National Museum of Natural History, Washington D.C.; Zoologische Staatssammlung, Mu¨nchen; Museum fu¨r Haustierkunde, Halle; the American Museum of Natural History, New-York. This work was funded by the Graduate School ‘Human Development in Landscapes’ at Kiel University (CAU) and supported by NERC project Grant NE/F003382/1. Radiocarbon dating was carried out at the Leibniz Laboratory, CAU. This work is licensed under a Creative Commons AttributionNonCommercial-NoDerivs 3.0 Unported License.Peer reviewedPublisher PD
Disease-specific mortality among stage I–III colorectal cancer patients with diabetes: a large population-based analysis
AIMS/HYPOTHESIS: The aim of our study was to investigate overall and disease-specific mortality of colorectal cancer patients with diabetes. METHODS: In this population-based study, we included all colorectal cancer patients, newly diagnosed with stage I–III cancer, between 1997 and 2007 in the registration area of the Eindhoven Cancer Registry. Stage of cancer, cancer treatment and comorbidities were actively collected by reviewing hospital medical records. Data on patients with and without diabetes were linked to Statistics Netherlands to assess vitality, date of death and underlying cause of death. Follow-up of all patients was completed until 1 January 2009. RESULTS: We included 6,974 patients with colon cancer and 3,888 patients with rectal cancer, of whom 820 (12%) and 404 (10%), respectively, had diabetes at the time of cancer diagnosis. During follow-up, death occurred in 611 (50%) of 1,224 cancer patients with diabetes and 3,817 (40%) of 9,638 cancer patients without diabetes. Multivariate Cox regression analyses, adjusted for age, sex, socioeconomic status, stage, lymph nodes examined, adjuvant therapy and year of diagnosis, showed that overall mortality was significantly higher for colon (HR 1.12, 95% CI 1.01, 1.25) and rectal (HR 1.21, 95% CI 1.03, 1.41) cancer patients with diabetes than for those without. Disease-specific mortality was only significantly increased for rectal cancer patients (HR 1.30, 95% CI 1.06, 1.60). CONCLUSIONS/INTERPRETATION: Diabetes at the time of rectal cancer diagnosis was independently associated with an increased risk of colorectal cancer mortality compared with no diabetes, suggesting a specific interaction between diabetes and rectal cancer. Future in-depth studies including detailed diabetes- and cancer-related variables should elucidate pathways
Iron Age and Anglo-Saxon genomes from East England reveal British migration history
British population history has been shaped by a series of immigrations, including the early Anglo-Saxon migrations after 400 CE. It remains an open question how these events affected the genetic composition of the current British population. Here, we present whole-genome sequences from 10 individuals excavated close to Cambridge in the East of England, ranging from the late Iron Age to the middle Anglo-Saxon period. By analysing shared rare variants with hundreds of modern samples from Britain and Europe, we estimate that on average the contemporary East English population derives 38% of its ancestry from Anglo-Saxon migrations. We gain further insight with a new method, rarecoal, which infers population history and identifies fine-scale genetic ancestry from rare variants. Using rarecoal we find that the Anglo-Saxon samples are closely related to modern Dutch and Danish populations, while the Iron Age samples share ancestors with multiple Northern European populations including Britain
The Diffusion of Humans and Cultures in the Course of the Spread of Farming
The most profound change in the relationship between humans and their
environment was the introduction of agriculture and pastoralism. [....] For an
understanding of the expansion process, it appears appropriate to apply a
diffusive model. Broadly, these numerical modeling approaches can be catego-
rized in correlative, continuous and discrete. Common to all approaches is the
comparison to collections of radiocarbon data that show the apparent wave of
advance of the transition to farming. However, these data sets differ in entry
density and data quality. Often they disregard local and regional specifics and
research gaps, or dating uncertainties. Thus, most of these data bases may only
be used on a very general, broad scale. One of the pitfalls of using
irregularly spaced or irregularly documented radiocarbon data becomes evident
from the map generated by Fort (this volume, Chapter 16): while the general
east-west and south-north trends become evident, some areas appear as having
undergone anomalously early transitions to farming. This may be due to faulty
entries into the data base or regional problems with radiocarbon dating, if not
unnoticed or undocumented laboratory mistakes.Comment: 20 pages, 5 figures, submitted to Diffusive Spreading in Nature,
Technology and Society, edited by Armin Bunde, J\"urgen Caro, J\"org
K\"arger, Gero Vogl, Chapter 1
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