| 1. |
- Karmin, Monika, et al.
(författare)
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A recent bottleneck of Y chromosome diversity coincides with a global change in culture.
- 2015
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 25:4
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Tidskriftsartikel (refereegranskat)abstract
- It is commonly thought that human genetic diversity in non-African populations was shaped primarily by an out-of-Africa dispersal 50-100 thousand yr ago (kya). Here, we present a study of 456 geographically diverse high-coverage Y chromosome sequences, including 299 newly reported samples. Applying ancient DNA calibration, we date the Y-chromosomal most recent common ancestor (MRCA) in Africa at 254 (95% CI 192-307) kya and detect a cluster of major non-African founder haplogroups in a narrow time interval at 47-52 kya, consistent with a rapid initial colonization model of Eurasia and Oceania after the out-of-Africa bottleneck. In contrast to demographic reconstructions based on mtDNA, we infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky. We hypothesize that this bottleneck is caused by cultural changes affecting variance of reproductive success among males.
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| 2. |
- Hjorth Larsen, Ask, et al.
(författare)
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The atomic simulation environment-a Python library for working with atoms
- 2017
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 29:27
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Forskningsöversikt (refereegranskat)abstract
- The atomic simulation environment (ASE) is a software package written in the Python programming language with the aim of setting up, steering, and analyzing atomistic simulations. In ASE, tasks are fully scripted in Python. The powerful syntax of Python combined with the NumPy array library make it possible to perform very complex simulation tasks. For example, a sequence of calculations may be performed with the use of a simple 'for-loop' construction. Calculations of energy, forces, stresses and other quantities are performed through interfaces to many external electronic structure codes or force fields using a uniform interface. On top of this calculator interface, ASE provides modules for performing many standard simulation tasks such as structure optimization, molecular dynamics, handling of constraints and performing nudged elastic band calculations.
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| 3. |
- Hammer-Rotzler, Bernadette, et al.
(författare)
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Distribution and surface enrichment of radionuclides in lead-bismuth eutectic from spallation targets
- 2016
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Ingår i: European Physical Journal Plus. - : Springer Science and Business Media LLC. - 2190-5444. ; 131:7
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Tidskriftsartikel (refereegranskat)abstract
- With the development of new high-power neutron spallation sources --both for scientific application and as neutron production tool for accelerator-driven systems-- the demand for experimentally obtained nuclear data on the residue nuclei production in the target is constantly increasing. In the present work, we examined two lead-bismuth-eutectic targets, irradiated with high-energy protons, concerning their radionuclide content and the spatial distribution of selected isotopes. The first one was the so-called ISOLDE target, being irradiated with 1-1.4GeV protons at CERN-ISOLDE, the second one was the MEGAPIE target, irradiated at PSI with 590MeV protons. In particular, we investigated the phenomenon of radionuclide enrichment on free surfaces in both targets. It turned out that considerable accumulation can be found especially in the case of lanthanides. The depletion process is enhanced at increased temperatures. The results are compared with theoretical predictions; some possible consequences of the findings are illustrated.
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| 4. |
- Jørgensen, Jakob Holm, et al.
(författare)
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Symmetry-Driven Band Gap Engineering in Hydrogen Functionalized Graphene
- 2016
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 10:12, s. 10798-10807
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Tidskriftsartikel (refereegranskat)abstract
- Band gap engineering in hydrogen functionalized graphene is demonstrated by changing the symmetry of the functionalization structures. Small differences in hydrogen adsorbate binding energies on graphene on Ir(111) allow tailoring of highly periodic functionalization structures favoring one distinct region of the moiré supercell. Scanning tunneling microscopy and X-ray photoelectron spectroscopy measurements show that a highly periodic hydrogen functionalized graphene sheet can thus be prepared by controlling the sample temperature (Ts) during hydrogen functionalization. At deposition temperatures of Ts = 645 K and above, hydrogen adsorbs exclusively on the HCP regions of the graphene/Ir(111) moiré structure. This finding is rationalized in terms of a slight preference for hydrogen clusters in the HCP regions over the FCC regions, as found by density functional theory calculations. Angle-resolved photoemission spectroscopy measurements demonstrate that the preferential functionalization of just one region of the moiré supercell results in a band gap opening with very limited associated band broadening. Thus, hydrogenation at elevated sample temperatures provides a pathway to efficient band gap engineering in graphene via the selective functionalization of specific regions of the moiré structure.
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| 5. |
- Kyhl, Line, et al.
(författare)
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Exciting H2 Molecules for Graphene Functionalization
- 2017
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851.
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen functionalization of graphene by exposure to vibrationally excited H2 molecules is investigated by combined scanning tunneling microscopy, high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy measurements, and density functional theory calculations. The measurements reveal that vibrationally excited H2 molecules dissociatively adsorb on graphene on Ir(111) resulting in nanopatterned hydrogen functionalization structures. Calculations demonstrate that the presence of the Ir surface below the graphene lowers the H2 dissociative adsorption barrier and allows for the adsorption reaction at energies well below the dissociation threshold of the H–H bond. The first reacting H2 molecule must contain considerable vibrational energy to overcome the dissociative adsorption barrier. However, this initial adsorption further activates the surface resulting in reduced barriers for dissociative adsorption of subsequent H2 molecules. This enables functionalization by H2 molecules with lower vibrational energy, yielding an avalanche effect for the hydrogenation reaction. These results provide an example of a catalytically active graphene-coated surface and additionally set the stage for a re-interpretation of previous experimental work involving elevated H2 background gas pressures in the presence of hot filaments.
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| 6. |
- Yates, T. Michael, et al.
(författare)
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SLC35A2-related congenital disorder of glycosylation : Defining the phenotype
- 2018
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Ingår i: European journal of paediatric neurology. - : ELSEVIER SCI LTD. - 1090-3798 .- 1532-2130. ; 22:6, s. 1095-1102
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Tidskriftsartikel (refereegranskat)abstract
- We aim to further delineate the phenotype associated with pathogenic variants in the SLC35A2 gene, and review all published literature to-date. This gene is located on the X chromosome and encodes a UDP-galactose transporter. Pathogenic variants in SLC35A2 cause a congenital disorder of glycosylation. The condition is rare, and less than twenty patients have been reported to-date. The phenotype is complex and has not been fully defined. Here, we present a series of five patients with de novo pathogenic variants in SLC35A2. The patients' phenotype includes developmental and epileptic encephalopathy with hypsarrhythmia, facial dysmorphism, severe intellectual disability, skeletal abnormalities, congenital cardiac disease and cortical visual impairment. Developmental and epileptic encephalopathy with hypsarrhythmia is present in most patients with SLC35A2 variants, and is drug-resistant in the majority of cases. Adrenocorticotropic hormone therapy may achieve partial or complete remission of seizures, but the effect is usually temporary. Isoelectric focusing of transferrins may be normal after infancy, therefore a congenital disorder of glycosylation should still be considered as a diagnosis in the presence of a suggestive phenotype. We also provide evidence that cortical visual impairment is part of the phenotypic spectrum.
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| 7. |
- Ziegelasch, Michael, 1966-
(författare)
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Diagnostic and prognostic potential of joint imaging in patients with anti-citrullinated protein antibodies
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of novel therapeutic strategies set new goals for the patients’ outcome, which aims to achieve remission. This goal requires early diagnosis of RA and prompt efficient pharmacotherapy. The introduction of anti-citrullinated protein antibodies (ACPA) two decades ago allowed an earlier RA diagnosis. However, there are indications that ACPA positivity is still associated with higher rates of radiographic damage. As the small joints in hands and feet commonly are the first involved sites of inflammation, the role of different imaging modalities were studied regarding their diagnostic and prognostic impact for assessment of arthritis in RA. Further, ultrasound (US) and radiography were used to study the association between RA-specific antibodies and the occurrence of arthritis and joint damage in systemic lupus erythematosus (SLE).The use of US allows assessment of soft tissue like joint capsules, tendons and bursae. Used for a live scanning, it is easy to detect effusions and edema. Doppler indicates vasoproliferation were inflammation is present. Also, US seems to be more sensitive than radiography to detect minimal structural changes located at bone surfaces. We wanted to investigate whether US findings in a pre-RA stage can predict development of arthritis.Digital X-ray radiogrammetry (DXR) is a technique based on computerized analyses of standard hand radiographs to calculate peripheral bone mineral density (BMD) of the three middle metacarpal bones (DXR-BMD). In order for early treatment decisions, we aimed to study whether changes in DXR-BMD loss after 3 months can predict radiographic damage in early RA.In conclusion, the studies showed that ACPA-positivity is still associated with a higher risk of radiographic damage regardless of early treatment decisions. Therefore, close radiographic monitoring and readiness to intensive treatment is warranted in ACPA-positive patients. This thesis also shows that erosions detected by US in ACPA-positive patients with arthralgia predict development of clinical arthritis. Also, the magnitude of DXR-BMD loss helps identify patients at higher risk for future radiographic damage, and may therefore help to improve early treatment decisions. Finally, US and radiography confirm a higher rate of arthritis and erosions also in SLE patients who are positive for RA-specific antibodies.
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