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| 2. |
- Lammer, H., et al.
(author)
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Geophysical and Atmospheric Evolution of Habitable Planets
- 2010
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In: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 10:1, s. 45-68
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Journal article (peer-reviewed)abstract
- The evolution of Earth-like habitable planets is a complex process that depends on the geodynamical and geophysical environments. In particular, it is necessary that plate tectonics remain active over billions of years. These geophysically active environments are strongly coupled to a planet's host star parameters, such as mass, luminosity and activity, orbit location of the habitable zone, and the planet's initial water inventory. Depending on the host star's radiation and particle flux evolution, the composition in the thermosphere, and the availability of an active magnetic dynamo, the atmospheres of Earth-like planets within their habitable zones are differently affected due to thermal and nonthermal escape processes. For some planets, strong atmospheric escape could even effect the stability of the atmosphere.
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| 3. |
- Kriegner, D., et al.
(author)
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Structural investigation of GaInP nanowires using X-ray diffraction
- 2013
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 543, s. 100-105
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Journal article (peer-reviewed)abstract
- In this work the structure of ternary GaxIn1-xP nanowires is investigated with respect to the chemical composition and homogeneity. The nanowires were grown by metal-organic vapor-phase epitaxy. For the investigation of ensemble fluctuations on several lateral length scales, X-ray diffraction reciprocal space maps have been analyzed. The data reveal a complicated varying materials composition across the sample and in the nanowires on the order of 20%. The use of modern synchrotron sources, where beam-sizes in the order of several 10 mu m are available, enables us to investigate compositional gradients along the sample by recording diffraction patterns at different positions. In addition, compositional variations were found also within single nanowires in X-ray energy dispersive spectroscopy measurements. (C) 2013 Elsevier B.V. All rights reserved.
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| 4. |
- Lammer, H., et al.
(author)
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What makes a planet habitable?
- 2009
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In: The Astronomy and Astrophysics Review. - : Springer Science and Business Media LLC. - 0935-4956 .- 1432-0754. ; 17:2, s. 181-249
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Research review (peer-reviewed)abstract
- This work reviews factors which are important for the evolution of habitable Earth-like planets such as the effects of the host star dependent radiation and particle fluxes on the evolution of atmospheres and initial water inventories. We discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets. The discoveries of methane-ethane surface lakes on Saturn's large moon Titan, subsurface water oceans or reservoirs inside the moons of Solar System gas giants such as Europa, Ganymede, Titan and Enceladus and more than 335 exoplanets, indicate that the classical definition of the habitable zone concept neglects more exotic habitats and may fail to be adequate for stars which are different from our Sun. A classification of four habitat types is proposed. Class I habitats represent bodies on which stellar and geophysical conditions allow Earth-analog planets to evolve so that complex multi-cellular life forms may originate. Class II habitats includes bodies on which life may evolve but due to stellar and geophysical conditions that are different from the class I habitats, the planets rather evolve toward Venus- or Mars-type worlds where complex life-forms may not develop. Class III habitats are planetary bodies where subsurface water oceans exist which interact directly with a silicate-rich core, while class IV habitats have liquid water layers between two ice layers, or liquids above ice. Furthermore, we discuss from the present viewpoint how life may have originated on early Earth, the possibilities that life may evolve on such Earth-like bodies and how future space missions may discover manifestations of extraterrestrial life.
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| 5. |
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| 6. |
- Heskel, Mary A., et al.
(author)
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Convergence in the temperature response of leaf respiration across biomes and plant functional types
- 2016
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In: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:14, s. 3832-3837
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Journal article (peer-reviewed)abstract
- Plant respiration constitutes a massive carbon flux to the atmosphere, and a major control on the evolution of the global carbon cycle. It therefore has the potential to modulate levels of climate change due to the human burning of fossil fuels. Neither current physiological nor terrestrial biosphere models adequately describe its short-term temperature response, and even minor differences in the shape of the response curve can significantly impact estimates of ecosystem carbon release and/or storage. Given this, it is critical to establish whether there are predictable patterns in the shape of the respiration-temperature response curve, and thus in the intrinsic temperature sensitivity of respiration across the globe. Analyzing measurements in a comprehensive database for 231 species spanning 7 biomes, we demonstrate that temperature-dependent increases in leaf respiration do not follow a commonly used exponential function. Instead, we find a decelerating function as leaves warm, reflecting a declining sensitivity to higher temperatures that is remarkably uniform across all biomes and plant functional types. Such convergence in the temperature sensitivity of leaf respiration suggests that there are universally applicable controls on the temperature response of plant energy metabolism, such that a single new function can predict the temperature dependence of leaf respiration for global vegetation. This simple function enables straightforward description of plant respiration in the land-surface components of coupled earth system models. Our cross-biome analyses shows significant implications for such fluxes in cold climates, generally projecting lower values compared with previous estimates.
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| 7. |
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| 8. |
- Jacobsson, Daniel, et al.
(author)
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Particle-assisted GaxIn1-xP nanowire growth for designed bandgap structures
- 2012
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In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 23:24
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Journal article (peer-reviewed)abstract
- Non-tapered vertically straight GaxIn1-xP nanowires were grown in a compositional range from Ga0.2In0.8P to pure GaP in particle-assisted mode by controlling the trimethylindium, trimethylgallium and hydrogen chloride flows in metal-organic vapor phase epitaxy. X-ray energy dispersive spectroscopy in transmission electron microscopy revealed homogeneous radial material composition in single nanowires, whereas variations in the material composition were found along the nanowires. High-resolution x-ray diffraction indicates a variation of the material composition on the order of about 19% measuring an entire sample area, i.e., including edge effects during growth. The non-capped nanowires emit room temperature photoluminescence strongly in the energy range of 1.43-2.16 eV, correlated with the bandgap expected from the material composition.
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| 11. |
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| 13. |
- Caroff, Philippe, et al.
(author)
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InAs film grown on Si(111) by Metalorganic Vapor Phase Epitaxy
- 2008
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 100, s. 042017-042017
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Conference paper (peer-reviewed)abstract
- We report the successful growth of high quality InAs films directly on Si( 111) by Metal Organic Vapor Phase Epitaxy. A nearly mirror-like and uniform InAs film is obtained at 580 C for a thickness of 2 mu m. We measured a high value of the electron mobility of 5100 cm(2)/Vs at room temperature. The growth is performed using a standard two-step procedure. The influence of the nucleation layer, group V flow rate, and layer thickness on the electrical and morphological properties of the InAs film have been investigated. We present results of our studies by Atomic Force Microscopy, Scanning Electron Microscopy, electrical Hall/van der Pauw and structural X-Ray Diffraction characterization.
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| 14. |
- Kriegner, D., et al.
(author)
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Unit cell parameters of wurtzite InP nanowires determined by x-ray diffraction
- 2011
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In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 22:42
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Journal article (peer-reviewed)abstract
- High resolution x-ray diffraction is used to study the structural properties of the wurtzite polytype of InP nanowires. Wurtzite InP nanowires are grown by metal-organic vapor phase epitaxy using S-doping. From the evaluation of the Bragg peak position we determine the lattice parameters of the wurtzite InP nanowires. The unit cell dimensions are found to differ from the ones expected from geometric conversion of the cubic bulk InP lattice constant. The atomic distances along the c direction are increased whereas the atomic spacing in the a direction is reduced in comparison to the corresponding distances in the zinc-blende phase. Using core/shell nanowires with a thin core and thick nominally intrinsic shells we are able to determine the lattice parameters of wurtzite InP with a negligible influence of the S-doping due to the much larger volume in the shell. The determined material properties will enable the ab initio calculation of electronic and optical properties of wurtzite InP nanowires.
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| 15. |
- Lehmann, U., et al.
(author)
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Efficacy of fish intake on vitamin D status: a meta-analysis of randomized controlled trials
- 2015
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In: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 102:4, s. 837-847
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Journal article (peer-reviewed)abstract
- Background: It is well known that fish is the major natural source of vitamin D in the diet; therefore, this meta-analysis investigated the influence of fish consumption in randomized controlled trials (RCTs) on serum 25-hydroxyvitamin D [25(OH)D] concentrations. Objective: A literature search was carried out in Medline, Embase, Web of Science, and the Cochrane Library (up to February 2014) for RCTs that investigated the effect of fish consumption on 25(OH)D concentrations in comparison to other dietary interventions. Results: Seven articles and 2 unpublished study data sets with 640 subjects and 14 study groups met the inclusion criteria and were included in this meta-analysis. Compared with controls, the consumption of fish increased 25(OH)D concentrations, on average, by 4.4 nmol/L (95% CI: 1.7, 7.1 nmol/L; P < 0.0001, I-2 = 25%; 9 studies). The type of the fish also played a key role: the consumption of fatty fish resulted in a mean difference of 6.8 nmol/L (95% CI: 3.7, 9.9 nmol/L; P < 0.0001, I-2 = 0%; 7 study groups), whereas for lean fish the mean difference was 1.9 nmol/L (95% CI: -2.3, 6.0 nmol/L; P < 0.38, I-2 = 37%; 7 study groups). Short-term studies (4-8 wk) showed a mean difference of 3.8 nmol/L (95% CI: 0.6, 6.9 nmol/L; P < 0.02, I-2 = 38%; 10 study groups), whereas in long-term studies (similar to 6 mo) the mean difference was 8.3 nmol/L (95% CI: 2.1, 14.5 nmol/L; P < 0.009, I-2 = 0%; 4 study groups). Conclusion: As the major food source of vitamin D, fish consumption increases concentrations of 25(OH)D, although recommended fish intakes cannot optimize vitamin D status.
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| 16. |
- Mckie, Brendan, et al.
(author)
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Evaluating the properties, fate and individual-to-ecosystem level impacts of contrasting microplastics in freshwaters
- 2023
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Reports (other academic/artistic)abstract
- Microplastic particles (MPs) are fragments, fibres and other shapes derived fromplastic polymers in the size range of 1–5 000 μm. Concern about the environmentalimpacts of MPs and their implications for human wellbeing has never been higher.Unfortunately, growth in the empirical understanding of the dynamics and impactsof MPs lags behind. This hinders the capacity of scientists, managers and policymakers to address public concerns about the true level of risk posed by MPs, andto develop effective management, policy and governance strategies for eliminatingor reducing those risks.Research on the behaviour and impacts of MPs in freshwater ecosystems is especiallydeficient, despite their vulnerability to inputs of plastic waste (e.g. via storm waterand other terrestrial runoff), and their capacity to act as key transport pathwaysthrough the landscape. This represents a substantial black box in our understandingof the dynamics of MPs from inland to the ocean.In seven research activities (5 mesocosm experiments, 1 field study and 1 literaturereview) we addressed two broad research questions:a) Initial fate and environmental interactions of MP particles in streams, includingbiofilm formation and sorption of chemical stressorsb) Ecological impacts of MPs on resource consumption, growth and survival oforganisms, and on key ecosystem processes.Among our key results addressing the initial fate and biofilm formation of MPparticles, we found that (i) biofilm formation generally made denser particles morebuoyant and caused more buoyant particles to sink faster, (ii) biofilms on polystyreneMPs supported more cyanobacteria than other polymers, and (iii) aquatic macrophytesincrease MP retention by up to 94 %.Among our key results addressing the ecological impacts of MPs, we found that almostall MP shapes and polymers studied had one or more effects on stream microbialorganisms and associated ecosystem processes (e.g. microbial respiration, detritusbreakdown), and/or on the life history of a model macroinvertebrate detritivore.We also provide evidence that effects of MPs on microbial organisms can propagateup food-chains to affect consumer growth and fat storage.Some MP impacts were similar to those of naturally occurring organic and inorganicparticles, whilst others represented a risk over and above that associated with naturalparticles.The number of MP impacts detected in our experiments provides sufficient basis for“moving beyond the precautionary principle” when motivating a need for monitoringand management – there is now sufficient evidence that MPs alter key aspects of thefunctioning of stream benthic food webs to motivate a need for action.Based on our results, we further provide a series of recommendations formonitoring,policy and management targeting MPs, and for future research.
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| 18. |
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| 19. |
- Suchankova, Petra, 1979, et al.
(author)
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The glucagon-like peptide-1 receptor as a potential treatment target in alcohol use disorder: evidence from human genetic association studies and a mouse model of alcohol dependence
- 2015
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In: Translational Psychiatry. - : Springer Science and Business Media LLC. - 2158-3188 .- 2158-3188. ; 5
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Journal article (peer-reviewed)abstract
- The hormone glucagon-like peptide-1 (GLP-1) regulates appetite and food intake. GLP-1 receptor (GLP-1R) activation also attenuates the reinforcing properties of alcohol in rodents. The present translational study is based on four human genetic association studies and one preclinical study providing data that support the hypothesis that GLP-1R may have a role in the pathophysiology of alcohol use disorder (AUD). Case-control analysis (N=908) was performed on a sample of individuals enrolled in the National Institute on Alcohol Abuse and Alcoholism (NIAAA) intramural research program. The Study of Addiction: Genetics and Environment (SAGE) sample (N=3803) was used for confirmation purposes. Post hoc analyses were carried out on data from a human laboratory study of intravenous alcohol self-administration (IV-ASA; N=81) in social drinkers and from a functional magnetic resonance imaging study in alcohol-dependent individuals (N=22) subjected to a Monetary Incentive Delay task. In the preclinical study, a GLP-1R agonist was evaluated in a mouse model of alcohol dependence to demonstrate the role of GLP-1R for alcohol consumption. The previously reported functional allele 168Ser (rs6923761) was nominally associated with AUD (P=0.004) in the NIAAA sample, which was partially replicated in males of the SAGE sample (P=0.033). The 168Ser/Ser genotype was further associated with increased alcohol administration and breath alcohol measures in the IV-ASA experiment and with higher BOLD response in the right globus pallidus when receiving notification of outcome for high monetary reward. Finally, GLP-1R agonism significantly reduced alcohol consumption in a mouse model of alcohol dependence. These convergent findings suggest that the GLP-1R may be an attractive target for personalized pharmacotherapy treatment of AUD.
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| 20. |
- Suchankova, Petra, 1979, et al.
(author)
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The Leu72Met Polymorphism of the Prepro-ghrelin Gene is Associated With Alcohol Consumption and Subjective Responses to Alcohol: Preliminary Findings
- 2017
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In: Alcohol and Alcoholism. - : Oxford University Press (OUP). - 0735-0414 .- 1464-3502. ; 52:4, s. 425-430
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Journal article (peer-reviewed)abstract
- The orexigenic peptide ghrelin may enhance the incentive value of food-, drug- and alcohol-related rewards. Consistent with preclinical findings, human studies indicate a role of ghrelin in alcohol use disorders (AUD). In the present study an a priori hypothesis-driven analysis was conducted to investigate whether a Leu72Met missense polymorphism (rs696217) in the prepro-ghrelin gene (GHRL), is associated with AUD, alcohol consumption and subjective responses to alcohol. Association analysis was performed using the National Institute on Alcohol Abuse and Alcoholism (NIAAA) clinical sample, comprising AUD individuals and controls (N = 1127). Then, a post-hoc analysis using data from a human laboratory study of intravenous alcohol self-administration (IV-ASA, N = 144) was performed to investigate the association of this SNP with subjective responses following a fixed dose of alcohol (priming phase) and alcohol self-administration (ad libitum phase). The case-control study revealed a trend association (N = 1127, OR = 0.665, CI = 0.44-1.01, P = 0.056) between AUD diagnosis and Leu72Met. In AUD subjects, the SNP was associated with significantly lower average drinks per day (n = 567, beta = -2.49, 95% CI = -4.34 to -0.64, P = 0.008) and significantly fewer heavy drinking days (n = 567, beta = -12.00, 95% CI = -19.10 to -4.89, P < 0.001). The IV-ASA study further revealed that 72Met carriers had greater subjective responses to alcohol (P < 0.05) when compared to Leu72Leu both at priming and during ad lib self-administration. Although preliminary, these findings suggest that the Leu72Leu genotype may lead to increased risk of AUD possibly via mechanisms involving a lower response to alcohol resulting in excessive alcohol consumption. Further investigations are warranted. We investigated whether a Leu72Met missense polymorphism in the prepro-ghrelin gene, is associated with alcohol use disorder, alcohol consumption and subjective responses to alcohol. Although preliminary, results suggest that the Leu72Leu genotype may lead to increased risk of alcohol use disorder possibly via mechanisms involving a lower response to alcohol.
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| 21. |
- Svensson, CPT, et al.
(author)
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Epitaxially grown GaP/GaAs1-xPx/GaP double heterostructure nanowires for optical applications
- 2005
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In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 16:6, s. 936-939
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Journal article (peer-reviewed)abstract
- We demonstrate metal organic vapour phase epitaxy growth of GaP/GaAs1-xPx/GaP double heterostructure nanowires on GaP(111)B, and report bright photoluminescence at room temperature. By using different PH3 to AsH3 flow ratios during growth of the GaAs1-xPx segment, we are able to control the composition of the segment, making it feasible to tune the wavelength of the emitted light. A photoluminescence system was employed to characterize the luminescence, and x-ray energy dispersive spectrometry and x-ray diffraction studies were used to investigate the composition of the segment. These double heterostructure nanowires could in the future be used in optoelectronic devices and as multi pie-wavelength fluorescent markers for biomedical applications.
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