| 1. |
- Davies, G., et al.
(author)
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Genetic contributions to variation in general cognitive function : a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53 949)
- 2015
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In: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 20:2, s. 183-192
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Journal article (peer-reviewed)abstract
- General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health-and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N = 53 949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P = 3.93 x 10(-9), MIR2113; rs17522122, P = 2.55 x 10(-8), AKAP6; rs10119, P = 5.67 x 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P = 1x10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N = 6617) and the Health and Retirement Study (N = 5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e. = 5%) and 28% (s.e. = 7%), respectively. Using polygenic prediction analysis, similar to 1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N = 5487; P = 1.5 x 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.
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| 2. |
- Davies, G., et al.
(author)
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Study of 300,486 individuals identifies 148 independent genetic loci influencing general cognitive function
- 2018
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9:1
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Journal article (peer-reviewed)abstract
- General cognitive function is a prominent and relatively stable human trait that is associated with many important life outcomes. We combine cognitive and genetic data from the CHARGE and COGENT consortia, and UK Biobank (total N = 300,486; age 16-102) and find 148 genome-wide significant independent loci (P < 5 × 10-8) associated with general cognitive function. Within the novel genetic loci are variants associated with neurodegenerative and neurodevelopmental disorders, physical and psychiatric illnesses, and brain structure. Gene-based analyses find 709 genes associated with general cognitive function. Expression levels across the cortex are associated with general cognitive function. Using polygenic scores, up to 4.3% of variance in general cognitive function is predicted in independent samples. We detect significant genetic overlap between general cognitive function, reaction time, and many health variables including eyesight, hypertension, and longevity. In conclusion we identify novel genetic loci and pathways contributing to the heritability of general cognitive function.
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| 3. |
- Dahl-Jensen, D., et al.
(author)
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Eemian interglacial reconstructed from a Greenland folded ice core
- 2013
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 493:7433, s. 489-494
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Journal article (peer-reviewed)abstract
- Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
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| 4. |
- Steen-Larsen, H. C., et al.
(author)
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Continuous monitoring of summer surface water vapor isotopic composition above the Greenland Ice Sheet
- 2013
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In: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 13:9, s. 4815-4828
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Journal article (peer-reviewed)abstract
- We present here surface water vapor isotopic measurements conducted from June to August 2010 at the NEEM (North Greenland Eemian Drilling Project) camp, NW Greenland (77.45 degrees N, 51.05 degrees W, 2484 m a.s.l.). Measurements were conducted at 9 different heights from 0.1m to 13.5m above the snow surface using two different types of cavity-enhanced near-infrared absorption spectroscopy analyzers. For each instrument specific protocols were developed for calibration and drift corrections. The inter-comparison of corrected results from different instruments reveals excellent reproducibility, stability, and precision with a standard deviations of similar to 0.23 parts per thousand for delta O-18 and similar to 1.4 parts per thousand for delta D. Diurnal and intraseasonal variations show strong relationships between changes in local surface humidity and water vapor isotopic composition, and with local and synoptic weather conditions. This variability probably results from the interplay between local moisture fluxes, linked with firn-air exchanges, boundary layer dynamics, and large-scale moisture advection. Particularly remarkable are several episodes characterized by high (> 40 parts per thousand) surface water vapor deuterium excess. Air mass back-trajectory calculations from atmospheric analyses and water tagging in the LMDZiso (Laboratory of Meteorology Dynamics Zoom-isotopic) atmospheric model reveal that these events are associated with predominant Arctic air mass origin. The analysis suggests that high deuterium excess levels are a result of strong kinetic fractionation during evaporation at the sea-ice margin.
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| 5. |
- Kjaer, Christina, et al.
(author)
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Luminescence Spectroscopy of Rhodamine Homodimer Dications in Vacuo Reveals Strong Dye-Dye Interactions
- 2019
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In: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 20:4, s. 533-537
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Journal article (peer-reviewed)abstract
- Being alone or together makes a difference for the photophysics of dyes but for ionic dyes it is difficult to quantify the interactions due to solvent screening and nearby counter ions. Gas-phase luminescence experiments are desirable and now possible based on recent developments in mass spectrometry. Here we present results on tailor-made rhodamine homodimers where two dye cations are separated by methylene linkers, (CH2)(n). In solution the fluorescence is almost identical to that from the monomer whereas the emission from bare cation dimers redshifts with decreasing n. In the absence of screening, the electric field from the charge on one dye is strong enough to polarize the other dye, both in the ground state and in the excited state. An electrostatic model based on symmetric dye responses (equal induced-dipole moments in ground state) captures the underlying physics and demonstrates interaction even at large distances. Our results have possible implications for gas-phase Forster Resonance Energy Transfer.
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| 6. |
- Dherbecourt, J. B., et al.
(author)
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Lidar Emitter and Multi-species greenhouse gases Observation iNstrument (LEMON) : advances on a multi-species differential absorption Lidar system
- 2022
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In: 73rd International Astronautical Congress, IAC 2022. - : International Astronautical Federation, IAF.
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Conference paper (peer-reviewed)abstract
- In the frame of LEMON project (Lidar Emitter and Multi-species greenhouse gases Observation iNstrument - European Union's Horizon 2020 research and innovation program, GA n°821868), we are developing a multi-species differential absorption Lidar (DIAL). The goal is to benefit from innovative technological developments in terms of optical emitter, spectral reference, to be able to address H2O and its isotope HDO at 1982 nm, CO2 at 2051 nm, and potentially CH4 at 2290 nm, for future ground-based range-resolved DIAL sensing, and with the prospect of future airborne integrated-path DIAL (IPDA). The infrared emitter is based on the combination of two specific, patented, no-seeder Nested Cavity OPOs (NesCOPOs) coupled to a single optical parametric amplifier (OPA) line for high energy pulses generation. Specific developments are also pursued on the frequency reference for the emitter, which is planned to be provided by a GPS referenced frequency comb against which the emitter output pulses can be heterodyned. Besides the instrument design, specific tests experiments have been carried out, covering a wide panel of activities: radiation testing of some critical components to assess the potential of some key components for future space applications, emitter and frequency reference testing, preliminary DIAL tests with laboratory test-beds and comparison with specific in-situ calibration instruments as well as additional innovative techniques evaluation for the emitter. The final instrument design was carried out and the sub-units are now being built.
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| 7. |
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| 8. |
- Guðlaugsdóttir, H., et al.
(author)
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The influence of volcanic eruptions on weather regimes over the North Atlantic simulated by ECHAM5/MPI-OM ensemble runs from 800 to 2000 CE
- 2018
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In: Atmospheric Research. - : Elsevier BV. - 0169-8095. ; 213, s. 211-223
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Journal article (peer-reviewed)abstract
- The volcanic fingerprint on the winter North Atlantic atmospheric circulation and climate is analyzed in six ensemble runs of ECHAM5/MPI-OM covering 800–2000 CE, both for equatorial and Northern Hemisphere (NH) eruptions. Large volcanic eruptions influence climate on both annual and decadal time scales due to dynamic interactions of different climate components in the Earth's system. It is well known that the North Atlantic Oscillation (NAO) tends to shift towards its positive phase during winter in the first 1–2 years after large tropical volcanic eruptions, causing warming over Europe, but other North Atlantic weather regimes have received less attention. Here we investigate the four dominant weather regimes in the North Atlantic: The negative and positive phase of NAO as well as the Atlantic Ridge, Scandinavian blocking. The volcanic fingerprint is detected as a change in the frequency of occurrence and anomalies in the wind and temperature fields as well as in the sea ice cover. We observe a strong significant increase in the frequency of Atlantic Ridge in the second year after equatorial eruptions that precede the NAO+ detected in year 3–5 as a result of a strong zonal wind anomalies in year 1–2. Evidence for a stronger polar vortex is detected in years 12–14 where NAO+ is detected both as a frequency increase and in the wind and temperature fields. A short-term response is also detected 2–4 years after NH eruptions. The longterm signal after NH eruptions indicate a weak polar vortex around a decade after an eruption. Although the signal after NH eruptions is weaker our results stress the need for further studies. The simulated atmospheric response recorded in ECHAM5 after volcanic eruptions suggest a more dynamic response than previously thought. The methodology used can also be applied to other forcing scenario, for example for future climate projections where the aim is to search for a long-term climate signal.
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| 9. |
- Steen, Robert O., 1978-, et al.
(author)
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Bis-cyclometallated Molecular Switches Based on 4,7-phenantroline and 1,5-naphthyridine Architecture
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Other publication (other academic/artistic)abstract
- Two new bis-terdentate ligands, 3,8-bis-(6-thiophen-2-yl-pyridin-2-yl)-[4,7]phenanthroline (L1) and 2,6-bis(6-(thiophen-2-yl)pyridin-2-yl)-1,5-naphthyridine (L2), capable of reversible double cyclometallation have been synthesized. Both syntheses proceeded via a Skraup synthesis followed by Stille cross-coupling with 2-thiophen-2-yl-6-tributylstannylpyridine to yield the final product. The Ru2(tpy)2-complex of L1 was shown to be capable of reversible cyclometallation, where the bis-cyclometallated (C,C) isomer of the complex had an oxidation potential of +249 mV while the oxidation potential of the doubly S-coordinated (S,S) complex was +987 mV. No ground state interaction between the Ru cores was however found. In theory the complex should display a third, mixed, state. An S,C-coordinated isomer would open the way for molecular electronic applications based on ternary logic. However, despite attempts the S,C-coordinated complex could not be generated.
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| 10. |
- Steen, Robert O., 1978-, et al.
(author)
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Coordination-mode pH-activated Molecular Switches based on Ruthenium(II) Oligopyridine Complex Architecture
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Other publication (other academic/artistic)abstract
- A number of [Ru(tpy)L] complexes (where L is a ligand based on the 6-thien-2-yl-2,2’-bipyridine motif) have been generated to study the ability of this terdentate motif to switch between a N,N,C and a N,N,S binding mode as a function of pH and irradiation. Whilst the parent system 6-thien-2-yl-2,2’-bipyridine (1) displayed facile switching between the orange and purple forms, heavier analogues displayed sluggish switching – most likely resulting from a large moment of inertia about the bond between the S/C-bonded thiophene ring and the chelating bipyridine unit. Prototypic unsymmetrical bimetallic complexes (C7S and C7C) have been generated in order to test if the binding mode of the switching unit can affect the oxidation potential of the remote [Ru(bpy)2(L)] unit. The results of cyclic voltammetry studies suggest that only weak electronic coupling between the metal cores exists, and that the coordination mode (N,N,C or N,N,S) of the thiophene moiety only has a small effect on the oxidation potential of the [Ru(bpy)2(L)] unit.
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