| 1. |
- Joshi, Peter K, et al.
(författare)
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Directional dominance on stature and cognition in diverse human populations
- 2015
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 523:7561, s. 459-462
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Tidskriftsartikel (refereegranskat)abstract
- Homozygosity has long been associated with rare, often devastating, Mendelian disorders, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10(-300), 2.1 × 10(-6), 2.5 × 10(-10) and 1.8 × 10(-10), respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months' less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been.
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| 2. |
- Vogelezang, Suzanne, et al.
(författare)
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Novel loci for childhood body mass index and shared heritability with adult cardiometabolic traits.
- 2020
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 16:10
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Tidskriftsartikel (refereegranskat)abstract
- The genetic background of childhood body mass index (BMI), and the extent to which the well-known associations of childhood BMI with adult diseases are explained by shared genetic factors, are largely unknown. We performed a genome-wide association study meta-analysis of BMI in 61,111 children aged between 2 and 10 years. Twenty-five independent loci reached genome-wide significance in the combined discovery and replication analyses. Two of these, located near NEDD4L and SLC45A3, have not previously been reported in relation to either childhood or adult BMI. Positive genetic correlations of childhood BMI with birth weight and adult BMI, waist-to-hip ratio, diastolic blood pressure and type 2 diabetes were detected (Rg ranging from 0.11 to 0.76, P-values <0.002). A negative genetic correlation of childhood BMI with age at menarche was observed. Our results suggest that the biological processes underlying childhood BMI largely, but not completely, overlap with those underlying adult BMI. The well-known observational associations of BMI in childhood with cardio-metabolic diseases in adulthood may reflect partial genetic overlap, but in light of previous evidence, it is also likely that they are explained through phenotypic continuity of BMI from childhood into adulthood.
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| 3. |
- Gron, Kurt J., et al.
(författare)
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Archaeological cereals as an isotope record of long-term soil health and anthropogenic amendment in southern Scandinavia
- 2021
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 253
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Tidskriftsartikel (refereegranskat)abstract
- Maintaining soil health is integral to agricultural production, and the archaeological record contains multiple lines of palaeoclimatic and palaeoenvironmental proxy evidence that can contribute to the understanding and analysis of long-term trajectories of change that are key for contextualizing 21st century global environmental challenges. Soil is a capital resource and its nutrient balance is modified by agricultural activities, making it necessary to ensure soil productivity is maintained and managed through human choices and actions. Since prehistory this has always been the case; soil is a non-renewable resource within a human lifetime. Here, we present and interpret carbon and nitrogen isotope analysis of charred cereals from southern Scandinavia. Anthropogenic effects on soils are evident from the initiation of farming 6000 years ago, as is amendment to counteract its effects. The earliest cereals were planted on pristine soils, and by the late Neolithic, agriculture extensified. By the Iron Age it was necessary to significantly amend depleted soils to maintain crop yields. We propose that these data provide a record of soil water retention, net precipitation and amendment. From the start of the Neolithic there is a concurrent decrease in both Δ13C and δ15N, mitigated only by the replacement of soil organic content in the form of manure in the Iron Age. The cereal isotopes provide a record of trajectories of agricultural sustainability and anthropogenic adaptation for nearly the entire history of farming in the region.
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| 4. |
- Abdullaev, Fatkhulla, et al.
(författare)
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Collective dynamics of Fermi-Bose mixtures with an oscillating scattering length
- 2019
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 99:3
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Tidskriftsartikel (refereegranskat)abstract
- Collective oscillations of superfluid mixtures of ultra cold fermionic and bosonic atoms are investigated while varying the fermion-boson scattering length. We study the dynamics with respect to excited center of mass modes and breathing modes in the mixture. Parametric resonances are also analyzed when the scattering length varies periodically in time, by comparing partial differential equation (PDE) models and ordinary differential equation (ODE) models for the dynamics. An application to the recent experiment with fermionic Li-6 and bosonic Li-7 atoms, which approximately have the same masses, is discussed.
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| 5. |
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| 6. |
- Hörnquist, Michael, 1969-
(författare)
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A periodically Ordered Structures in One Dimension
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with different aspects of aperiodically ordered structures in one dimension. The approach is entirely theoretical, and the models used have various relevance for real systems. The main objective is to make a general study of how the solutions to some well-known equations behave when they are used to describe physical phenomena in structures which are aperiodically ordered.To obtain structures that are in some sense generic for aperiodic order, we use different sequences such as the Fibonacci sequence, the Thue-Morse sequence, the period-doubling sequence, the Rudin-Shapiro sequence, etc. We let some physical entities, such as on-site potentials or atomic masses, be ordered according to these sequences.One system studied is a tight-binding Schrödinger equation where the on-site potentialis modulated by some different circle sequences. It is found that for almost all such sequences related to the precious means, the electron spectra are purely singular continuous and of zero Lebesgue measure. A closely related study is for chains of aperiodically ordered quantum dots. The systems are modelled by a Kronig-Penney potential, and we calculate their conductance as a function of the Fermi level for realistic dimensions of such chains. We find some signs that we interpret as fingerprints of the singular continuous spectra these models possess in the limit of an infinite number of dots.Inspired by the fact that proteins can be considered as aperiodic chains and the somewhat successful attempts to classify their folding properties by use of the methods of block variables, we apply the same concept to some different deterministic aperiodic sequences. There turns out, however, to be no direct correspondence between the behaviour of the block variables and other properties of the sequences.The rest of the studies are about phenomena that need nonlinear terms in the equations for their description. One study is for how the wavefunction for an initially localized polaron in an aperiodically ordered lattice will spread. The governing equation we use is the discrete nonlinear Schrödinger equation (DNLS). We find that for a large enough nonlinearity, the probability of finding the quasiparticle at the initial site will always be nonzero and the participation number finite for all systems under study (self-trapping). For potentials yielding a singular continuous energy spectrum in the linear limit, selftrapping seems to appear for arbitrarily small nonlinearities. We also find that the root-mean-square width of the wave packet will increase infinitely with time for those of the studied systems which have a continuous part in their linear energy spectra, even when self-trapping has occurred.Another study is for arrays of Josephson junctions, described by the perturbed discrete sine-Gordon equation. The junctions are of two different kinds and ordered aperiodically but equidistantly. We study the dynamics of a single fluxon in such a lattice.With the use of an effective potential we explain the behaviour of the fluxon when it gets pinned in different arrays. The potential also gives a qualitative understanding of the deviation of the velocity of a propagating fluxon compared with an earlier obtained formula. It turns out that the self-similarity of the underlying sequences is important for the detailed dynamics, but not for the speed of a propagating fluxon.Finally there are investigations of various aspects of lattice dynamics when the atoms in the lattice have two different masses ( diatomic lattices) and are ordered according to some of the sequences mentioned above. This time we use classical mechanics to obtain the governing equations of motion.A study of solitary wave propagation in aperiodically ordered diatomic Tod a lattices reveals that the damping is considerable less for these systems than for a random lattice. The short range correlation between the atoms in the aperiodic lattices seems to be of main importance for how much the wave is damped. We suggest therefore that the entropy according to Shannon might be a relevant measure for the properties of the lattices in this case. It is shown that this measure yields at least an approximative agreement with what is actually achieved by our numerical experiments.The anharmonic terms in the potentials used can give rise to localized modes in lattices which only have extended modes in the harmonic approximation. This intrinsic localization is often referred to as discrete breathers. We find such modes numerically in some aperiodically ordered diatomic lattices in two different ways. The first method is known as the rotating wave approximation, which essentially means that we discard all harmonics except the one of lowest frequency. The second method is the use of the anti-continuous limit, which in this case refers to when the larger mass-value is infinite. In this limit, the system is integrable and one can find a solution to the equations of motion. This solution is then continued by the implicit function theorem to finite values of the larger mass.In analogy with the polaron study mentioned above, we also study the same phenomena for these classical models and energy localization. This means that we excite a few sites in the lattice and follow how the energy will spread in the system as time proceeds. We find the propagation to be correlated to the underlying dispersion relation and to the nature of the phase space for a reduced system.
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| 7. |
- Schönenberger, Silvia, et al.
(författare)
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Association of General Anesthesia vs Procedural Sedation With Functional Outcome Among Patients With Acute Ischemic Stroke Undergoing Thrombectomy: A Systematic Review and Meta-analysis.
- 2019
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Ingår i: JAMA. - : American Medical Association (AMA). - 1538-3598 .- 0098-7484. ; 322:13, s. 1283-1293
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Tidskriftsartikel (refereegranskat)abstract
- General anesthesia during thrombectomy for acute ischemic stroke has been associated with poor neurological outcome in nonrandomized studies. Three single-center randomized trials reported no significantly different or improved outcomes for patients who received general anesthesia compared with procedural sedation.To detect differences in functional outcome at 3 months between patients who received general anesthesia vs procedural sedation during thrombectomy for anterior circulation acute ischemic stroke.MEDLINE search for English-language articles published from January 1, 1980, to July 31, 2019.Randomized clinical trials of adults with a National Institutes of Health Stroke Scale score of at least 10 and anterior circulation acute ischemic stroke assigned to receive general anesthesia or procedural sedation during thrombectomy.Individual patient data were obtained from 3 single-center, randomized, parallel-group, open-label treatment trials with blinded end point evaluation that met inclusion criteria and were analyzed using fixed-effects meta-analysis.Degree of disability, measured via the modified Rankin Scale (mRS) score (range 0-6; lower scores indicate less disability), analyzed with the common odds ratio (cOR) to detect the ordinal shift in the distribution of disability over the range of mRS scores.A total of 368 patients (mean [SD] age, 71.5 [12.9] years; 163 [44.3%] women; median [interquartile range] National Institutes of Health Stroke Scale score, 17 [14-21]) were included in the analysis, including 183 (49.7%) who received general anesthesia and 185 (50.3%) who received procedural sedation. The mean 3-month mRS score was 2.8 (95% CI, 2.5-3.1) in the general anesthesia group vs 3.2 (95% CI, 3.0-3.5) in the procedural sedation group (difference, 0.43 [95% CI, 0.03-0.83]; cOR, 1.58 [95% CI, 1.09-2.29]; P=.02). Among prespecified adverse events, only hypotension (decline in systolic blood pressure of more than 20% from baseline) (80.8% vs 53.1%; OR, 4.26 [95% CI, 2.55-7.09]; P<.001) and blood pressure variability (systolic blood pressure >180 mm Hg or <120 mm Hg) (79.7 vs 62.3%; OR, 2.42 [95% CI, 1.49-3.93]; P<.001) were significantly more common in the general anesthesia group.Among patients with acute ischemic stroke involving the anterior circulation undergoing thrombectomy, the use of protocol-based general anesthesia, compared with procedural sedation, was significantly associated with less disability at 3 months. These findings should be interpreted tentatively, given that the individual trials examined were single-center trials and disability was the primary outcome in only 1 trial.
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| 8. |
- Sørensen, Mads Peter, et al.
(författare)
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The dynamics of magnetic vortices in type II superconductors with pinning sites studied by the time dependent Ginzburg–Landau model
- 2017
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Ingår i: Physica. C, Superconductivity. - Amsterdam : Elsevier. - 0921-4534 .- 1873-2143. ; 533, s. 40-43
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the dynamics of magnetic vortices in type II superconductors with normal state pinning sites using the Ginzburg–Landau equations. Simulation results demonstrate hopping of vortices between pinning sites, influenced by external magnetic fields and external currents. The system is highly nonlinear and the vortices show complex nonlinear dynamical behaviour.
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