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Sökning: WFRF:(HERTEL P)

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  • Chumak, A. V., et al. (författare)
  • Advances in Magnetics Roadmap on Spin-Wave Computing
  • 2022
  • Ingår i: IEEE Transactions on Magnetics. - 0018-9464. ; 58:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnonics addresses the physical properties of spin waves and utilizes them for data processing. Scalability down to atomic dimensions, operation in the GHz-to-THz frequency range, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS are just a few of many advantages offered by magnons. Although magnonics is still primarily positioned in the academic domain, the scientific and technological challenges of the field are being extensively investigated, and many proof-of-concept prototypes have already been realized in laboratories. This roadmap is a product of the collective work of many authors that covers versatile spin-wave computing approaches, conceptual building blocks, and underlying physical phenomena. In particular, the roadmap discusses the computation operations with Boolean digital data, unconventional approaches like neuromorphic computing, and the progress towards magnon-based quantum computing. The article is organized as a collection of sub-sections grouped into seven large thematic sections. Each sub-section is prepared by one or a group of authors and concludes with a brief description of current challenges and the outlook of further development for each research direction. Author
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  • Birney, Ewan, et al. (författare)
  • Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project
  • 2007
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 447:7146, s. 799-816
  • Tidskriftsartikel (refereegranskat)abstract
    • We report the generation and analysis of functional data from multiple, diverse experiments performed on a targeted 1% of the human genome as part of the pilot phase of the ENCODE Project. These data have been further integrated and augmented by a number of evolutionary and computational analyses. Together, our results advance the collective knowledge about human genome function in several major areas. First, our studies provide convincing evidence that the genome is pervasively transcribed, such that the majority of its bases can be found in primary transcripts, including non-protein-coding transcripts, and those that extensively overlap one another. Second, systematic examination of transcriptional regulation has yielded new understanding about transcription start sites, including their relationship to specific regulatory sequences and features of chromatin accessibility and histone modification. Third, a more sophisticated view of chromatin structure has emerged, including its inter-relationship with DNA replication and transcriptional regulation. Finally, integration of these new sources of information, in particular with respect to mammalian evolution based on inter- and intra-species sequence comparisons, has yielded new mechanistic and evolutionary insights concerning the functional landscape of the human genome. Together, these studies are defining a path for pursuit of a more comprehensive characterization of human genome function.
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  • Cherifi-Hertel, S., et al. (författare)
  • Non-Ising and chiral ferroelectric domain walls revealed by nonlinear optical microscopy
  • 2017
  • Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 8
  • Tidskriftsartikel (refereegranskat)abstract
    • The properties of ferroelectric domain walls can significantly differ from those of their parent material. Elucidating their internal structure is essential for the design of advanced devices exploiting nanoscale ferroicity and such localized functional properties. Here, we probe the internal structure of 180° ferroelectric domain walls in lead zirconate titanate (PZT) thin films and lithium tantalate bulk crystals by means of second-harmonic generation microscopy. In both systems, we detect a pronounced second-harmonic signal at the walls. Local polarimetry analysis of this signal combined with numerical modelling reveals the existence of a planar polarization within the walls, with Néel and Bloch-like configurations in PZT and lithium tantalate, respectively. Moreover, we find domain wall chirality reversal at line defects crossing lithium tantalate crystals. Our results demonstrate a clear deviation from the ideal Ising configuration that is traditionally expected in uniaxial ferroelectrics, corroborating recent theoretical predictions of a more complex, often chiral structure.
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  • Skjoth, Carsten, et al. (författare)
  • Identifying urban sources as cause of elevated grass pollen concentrations using GIS and remote sensing
  • 2013
  • Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 10:1, s. 541-554
  • Tidskriftsartikel (refereegranskat)abstract
    • We examine here the hypothesis that during flowering, the grass pollen concentrations at a specific site reflect the distribution of grass pollen sources within a few kilometres of this site. We perform this analysis on data from a measurement campaign in the city of Aarhus (Denmark) using three pollen traps and by comparing these observations with a novel inventory of grass pollen sources. The source inventory is based on a new methodology developed for urban-scale grass pollen sources. The new methodology is believed to be generally applicable for the European area, as it relies on commonly available remote sensing data combined with management information for local grass areas. The inventory has identified a number of grass pollen source areas present within the city domain. The comparison of the measured pollen concentrations with the inventory shows that the atmospheric concentrations of grass pollen in the urban zone reflect the source areas identified in the inventory, and that the pollen sources that are found to affect the pollen levels are located near or within the city domain. The results also show that during days with peak levels of pollen concentrations there is no correlation between the three urban traps and an operational trap located just 60 km away. This finding suggests that during intense flowering, the grass pollen concentration mirrors the local source distribution and is thus a local-scale phenomenon. Model simulations aimed at assessing population exposure to pollen levels are therefore recommended to take into account both local sources and local atmospheric transport, and not to rely only on describing regional to long-range transport of pollen. The derived pollen source inventory can be entered into local-scale atmospheric transport models in combination with other components that simulate pollen release in order to calculate urban-scale variations in the grass pollen load. The gridded inventory with a resolution of 14m is therefore made available as supplementary material to this paper, and the verifying grass pollen observations are additionally available in tabular form.
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  • Sutton, M. A., et al. (författare)
  • Towards a climate-dependent paradigm of ammonia emission and deposition
  • 2013
  • Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2970 .- 0962-8436. ; 368:1621
  • Tidskriftsartikel (refereegranskat)abstract
    • Existing descriptions of bi-directional ammonia (NH3) land-atmosphere exchange incorporate temperature and moisture controls, and are beginning to be used in regional chemical transport models. However, such models have typically applied simpler emission factors to upscale the main NH3 emission terms. While this approach has successfully simulated the main spatial patterns on local to global scales, it fails to address the environment-and climate-dependence of emissions. To handle these issues, we outline the basis for a new modelling paradigm where both NH3 emissions and deposition are calculated online according to diurnal, seasonal and spatial differences in meteorology. We show how measurements reveal a strong, but complex pattern of climatic dependence, which is increasingly being characterized using ground-based NH3 monitoring and satellite observations, while advances in process-based modelling are illustrated for agricultural and natural sources, including a global application for seabird colonies. A future architecture for NH3 emission-deposition modelling is proposed that integrates the spatio-temporal interactions, and provides the necessary foundation to assess the consequences of climate change. Based on available measurements, a first empirical estimate suggests that 5 degrees C warming would increase emissions by 42 per cent (28-67%). Together with increased anthropogenic activity, global NH3 emissions may increase from 65 (45-85) Tg N in 2008 to reach 132 (89-179) Tg by 2100.
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  • Boyle, Mark, et al. (författare)
  • Excitation dynamics of Rydberg states in C60
  • 2005
  • Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 36, s. 339-351
  • Tidskriftsartikel (refereegranskat)abstract
    • The electron and nuclear dynamics of C60 fullerenes irradiated with femtosecond laser pulses are investigated with photoelectron and photoion spectroscopy. The focus of this work is the detailed exploration of the population mechanism of Rydberg levels within the excitation process of neutral C60. The effect of excitation wavelength, intensity, chirp, and polarization on the kinetic energy distribution of photoelectrons in single-pulse experiments gives first insight into the underlying processes. In combination with time-resolved two-color pump-probe spectroscopy depending on either pump, or probe pulse intensity, a more complete picture of the interaction can be drawn. The results point towards a very interesting but nevertheless complex behavior including four steps: (i) non-adiabatic multielectron excitation of the HOMO (hu) → LUMO+1 (t1g) transition; (ii) thermalization within the hot electron cloud on a time scale below 100fs, followed by a coupling of energy to vibrational modes of the molecule via doorway state(s); (iii) population of electronically excited Rydberg states by multiphoton absorption, and (iv) single photon ionization from the excited Rydberg states. This excitation process results in a characteristic sequence of photoelectron lines in the photoemission spectra. The comparison of the experimental results with recent theoretical work gives convincing evidence that non-adiabatic multielectron dynamics (NMED) plays a key role for the understanding of the response of C60 to short-pulse laser radiation.
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  • Boyle, Mark, et al. (författare)
  • Two colour pump-probe study and internal energy dependence of Rydberg state excitation
  • 2004
  • Ingår i: Physical Review A. - 1050-2947. ; 70
  • Tidskriftsartikel (refereegranskat)abstract
    • Excitation of Rydberg states in isolated C60 is studied by time-resolved photoelectron spectroscopy in a femtosecond two-color pump-probe experiment. The relaxation time for electron-electron interaction is determined to be approximately 100 fs with the t1g(LUMO + 1) orbital being considered to define the doorway state in a nonadiabatic multielectron excitation process. The internal energy stored in vibrational modes of the C60 at 770 K is found to support the excitation process very efficiently while in "cold" C60 (80 K), no significant Rydberg population is detected.
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  • Braasch, Ingo, et al. (författare)
  • The spotted gar genome illuminates vertebrate evolution and facilitates human-teleost comparisons
  • 2016
  • Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 48:4, s. 427-437
  • Tidskriftsartikel (refereegranskat)abstract
    • To connect human biology to fish biomedical models, we sequenced the genome of spotted gar (Lepisosteus oculatus), whose lineage diverged from teleosts before teleost genome duplication (TGD). The slowly evolving gar genome has conserved in content and size many entire chromosomes from bony vertebrate ancestors. Gar bridges teleosts to tetrapods by illuminating the evolution of immunity, mineralization and development (mediated, for example, by Hox, ParaHox and microRNA genes). Numerous conserved noncoding elements (CNEs; often cis regulatory) undetectable in direct human-teleost comparisons become apparent using gar: functional studies uncovered conserved roles for such cryptic CNEs, facilitating annotation of sequences identified in human genome-wide association studies. Transcriptomic analyses showed that the sums of expression domains and expression levels for duplicated teleost genes often approximate the patterns and levels of expression for gar genes, consistent with subfunctionalization. The gar genome provides a resource for understanding evolution after genome duplication, the origin of vertebrate genomes and the function of human regulatory sequences.
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  • Camenzind, Tessa, et al. (författare)
  • Increases in soil aggregation following phosphorus additions in a tropical premontane forest are not driven by root and arbuscular mycorrhizal fungal abundances
  • 2016
  • Ingår i: Frontiers in Earth Science. - : Frontiers Media SA. - 2296-6463. ; 3
  • Tidskriftsartikel (refereegranskat)abstract
    • Tropical ecosystems have an important role in global change scenarios, in part because they serve as a large terrestrial carbon pool. Carbon protection is mediated by soil aggregation processes, whereby biotic and abiotic factors influence the formation and stability of aggregates. Nutrient additions may affect soil structure indirectly by simultaneous shifts in biotic factors, mainly roots, and fungal hyphae, but also via impacts on abiotic soil properties. Here, we tested the hypothesis that soil aggregation will be affected by nutrient additions primarily via changes in arbuscular mycorrhizal fungal (AMF) hyphae and root length in a pristine tropical forest system. Therefore, the percentage of water-stable macroaggregates (> 250 µm) (WSA) and the soil mean weight diameter (MWD) was analyzed, as well as nutrient contents, pH, root length, and AMF abundance. Phosphorus additions significantly increased the amount of WSA, which was consistent across two different sampling times. Despite a positive effect of phosphorus additions on extra-radical AMF biomass, no relationship between WSA and extra-radical AMF nor roots was revealed by regression analyses, contrary to the proposed hypothesis. These findings emphasize the importance of analyzing soil structure in understudied tropical systems, since it might be affected by increasing nutrient deposition expected in the future.
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  • Geels, C., et al. (författare)
  • Improved modelling of atmospheric ammonia over Denmark using the coupled modelling system DAMOS
  • 2012
  • Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 9:7, s. 2625-2647
  • Tidskriftsartikel (refereegranskat)abstract
    • A local-scale Gaussian dispersion-deposition model (OML-DEP) has been coupled to a regional chemistry-transport model (DEHM with a resolution of approximately 6 km x 6 km over Denmark) in the Danish Ammonia Modelling System, DAMOS. Thereby, it has been possible to model the distribution of ammonia concentrations and depositions on a spatial resolution down to 400 m x 400 m for selected areas in Denmark. DAMOS has been validated against measured concentrations from the dense measuring network covering Denmark. Here measured data from 21 sites are included and the validation period covers 2-5 years within the period 2005-2009. A standard time series analysis (using statistic parameters like correlation and bias) shows that the coupled model system captures the measured time series better than the regional- scale model alone. However, our study also shows that about 50% of the modelled concentration level at a given location originates from non-local emission sources. The local-scale model covers a domain of 16 km x 16 km, and of the locally released ammonia (NH3) within this domain, our simulations at five sites show that 14-27% of the locally (within 16 km x 16 km) emitted NH3 also deposits locally. These results underline the importance of including both high-resolution local-scale modelling of NH3 as well as the regional-scale component described by the regional model. The DAMOS system can be used as a tool in environmental management in relation to assessments of total nitrogen load of sensitive nature areas in intense agricultural regions. However, high spatio-temporal resolution in input parameters like NH3 emissions and land-use data is required.
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  • Grigelioniene, Giedre, et al. (författare)
  • Asn540Lys mutation in fibroblast growth factor receptor 3 and phenotype in hypochondroplasia
  • 2000
  • Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 89:9, s. 1072-1076
  • Tidskriftsartikel (refereegranskat)abstract
    • Hypochondroplasia is characterized by a disproportionate short stature with rhizomelic shortening of the limbs. Amino acid substitutions Asn540Lys, Asn540Thr and Ile538Val in the fibroblast growth factor receptor 3 (FGFR3) are considered to cause hypochondroplasia. In this study we examined the FGFR3 gene for the previously described hypochondroplasia mutations and the phenotype of 23 probands with clinically and radiologically diagnosed hypochondroplasia. For the phenotype comparison, the patients were divided into two groups: Group 1: hypochondroplasia with Asn540Lys substitution; Group 2: hypochondroplasia with no mutations identified so far. A three-generation family negative for the known hypochondroplasia mutations was examined with polymorphic markers flanking the FGFR1, FGFR2 and FGFR3 genes. Nine (39%) of 23 probands were found to be heterozygous for the Asn540Lys substitution. The individuals positive for the Asn540Lys substitution were significantly more disproportionate than the individuals without this mutation. In this respect, a genotype-phenotype correlation was found in our patients. However, some individuals belonging to the group without mutations identified so far showed similarly abnormal proportions. Genotyping/haplotyping in the three-generation family with hypochondroplasia showed that FGFR1, FGFR2 and FGFR3 genes were not linked to the hypochondroplasia phenotype in this family, thus further confirming the genetic heterogeneity of hypochondroplasia. CONCLUSION: Individuals with hypochondroplasia heterozygous for the Asn540Lys substitution are significantly more disproportionate than individuals without this mutation. Our study further confirms the clinical and genetic heterogeneity of hypochondroplasia.
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  • Hertel, Jens K., et al. (författare)
  • FTO, Type 2 Diabetes, and Weight Gain Throughout Adult Life A Meta-Analysis of 41,504 Subjects From the Scandinavian HUNT, MDC, and MPP Studies
  • 2011
  • Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 60:5, s. 1637-1644
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE-FTO is the most important polygene identified for obesity. We aimed to investigate whether a variant in FTO affects type 2 diabetes risk entirely through its effect on BMI and how FTO) influences BMI across adult life span. RESEARCH DESIGN AND METHODS-Through regression models, we assessed the relationship between the FTO single nucleotide polymorphisms rs9939609, type 2 diabetes, and BMI across life span in subjects from the Norwegian population-based HUNT study using cross-sectional and longitudinal perspectives. For replication and meta-analysis, we used data from the Malmo Diet and Cancer (MDC) and Malmo Preventive Project (MPP) cohorts, comprising a total sample of 41,504 Scandinavians. RESULTS-The meta-analysis revealed a highly significant association for rs9939609 with both type 2 diabetes (OR 1.13; P = 4.5 x 10(-8)) and the risk to develop incident type 2 diabetes (OR 1.16; P = 3.2 x 10(-8)). The associations remained also after correction for BMI and other anthropometric measures. Furthermore, we confirmed the strong effect on BMI (0.28 kg/m(2) per risk allele; P = 2.0 x 10(-26), with no heterogeneity between different age-groups. We found no differences in change of BMI over time according to rs9939609 risk alleles, neither overall (Delta BMI = 0.0 [-0.05, 0.05]) nor in any individual age stratum, indicating no further weight gain attributable to FTO genotype in adults. CONCLUSIONS-We have identified that a variant in FTO alters type 2 diabetes risk partly independent of its observed effect on BMI. The additional weight gain as a result of the FTO risk variant seems to occur before adulthood, and the BMI difference remains stable thereafter. Diabetes 60:1637-1644, 2011
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  • Hertel, J K, et al. (författare)
  • Genetic analysis of recently identified type 2 diabetes loci in 1,638 unselected patients with type 2 diabetes and 1,858 control participants from a Norwegian population-based cohort (the HUNT study)
  • 2008
  • Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 51:6, s. 971-977
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims/hypothesis Recent genome-wide association studies performed in selected patients and control participants have provided strong support for several new type 2 diabetes susceptibility loci. To get a better estimation of the true risk conferred by these novel loci, we tested a completely unselected population of type 2 diabetes patients from a Norwegian health survey (the HUNT study). Methods We genotyped single nucleotide polymorphisms (SNPs) in PKN2, IGFBP2, FLJ39370 (also known as C4ORF32), CDKAL1, SLC30A8, CDKN2B, HHEX and FTO using a Norwegian population-based sample of 1,638 patients with type 2 diabetes and 1,858 non-diabetic control participants (the HUNT Study), for all of whom data on BMI, WHR, cholesterol and triacylglycerol levels were available. We used diabetes, measures of obesity and lipid values as phenotypes in case-control and quantitative association study designs. Results We replicated the association with type 2 diabetes for rs10811661 in the vicinity of CDKN2B (OR 1.20, 95% CI: 1.06-1.37, p=0.004), rs9939609 in FTO (OR 1.14, 95% CI: 1.04-1.25, p=0.006) and rs13266634 in SLC30A8 (OR 1.20, 95% CI: 1.09-1.33, p=3.9x10(-4)). We found borderline significant association for the IGFBP2 SNP rs4402960 (OR 1.10, 95% CI: 0.99-1.22). Results for the HHEX SNP (rs1111875) and the CDKAL1 SNP (rs7756992) were non-significant, but the magnitude of effect was similar to previous estimates. We found no support for an association with the less consistently replicated FLJ39370 or PKN2 SNPs. In agreement with previous studies, FTO was most strongly associated with BMI (p=8.4x10(-4)). Conclusions/interpretation Our data show that SNPs near IGFBP2, CDKAL1, SLC30A8, CDKN2B, HHEX and FTO are also associated with diabetes in non-selected patients with type 2 diabetes.
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