| 1. |
- Antonov, A. N., et al.
(författare)
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The electron-ion scattering experiment ELISe at the International Facility for Antiproton and Ion Research (FAIR)-A conceptual design study
- 2011
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002 .- 0167-5087. ; 637:1, s. 60-76
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Tidskriftsartikel (refereegranskat)abstract
- The electron-ion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented. (C) 2011 Elsevier B.V. All rights reserved.
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| 2. |
- Daniau, A. -L, et al.
(författare)
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predictability of biomass burning in response to climate changes
- 2012
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 26, s. GB4007-
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Tidskriftsartikel (refereegranskat)abstract
- Climate is an important control on biomass burning, but the sensitivity of fire to changes in temperature and moisture balance has not been quantified. We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo-fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming.
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| 3. |
- Bailly, X, et al.
(författare)
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The chimerical and multifaceted marine acoel Symsagittifera roscoffensis: from photosymbiosis to brain regeneration
- 2014
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- A remarkable example of biological engineering is the capability of some marine animals to take advantage of photosynthesis by hosting symbiotic algae. This capacity, referred to as photosymbiosis, is based on structural and functional complexes that involve two distantly unrelated organisms. These stable photosymbiotic associations between metazoans and photosynthetic protists play fundamental roles in marine ecology as exemplified by reef communities and their vulnerability to global changes threats. Here we introduce a photosymbiotic tidal acoel flatworm, Symsagittifera roscoffensis, and its obligatory green algal photosymbiont, Tetraselmis convolutae (Lack of the algal partner invariably results in acoel lethality emphasizing the mandatory nature of the photosymbiotic algae for the animal's survival). Together they form a composite photosymbiotic unit, which can be reared in controlled conditions that provide easy access to key life-cycle events ranging from early embryogenesis through the induction of photosymbiosis in aposymbiotic juveniles to the emergence of a functional “solar-powered” mature stage. Since it is possible to grow both algae and host under precisely controlled culture conditions, it is now possible to design a range of new experimental protocols that address the mechanisms and evolution of photosymbiosis. S. roscoffensis thus represents an emerging model system with experimental advantages that complement those of other photosymbiotic species, in particular corals. The basal taxonomic position of S. roscoffensis (and acoels in general) also makes it a relevant model for evolutionary studies of development, stem cell biology and regeneration. Finally, it's autotrophic lifestyle and lack of calcification make S. roscoffensis a favorable system to study the role of symbiosis in the response of marine organisms to climate change (e.g., ocean warming and acidification). In this article we summarize the state of knowledge of the biology of S. roscoffensis and its algal partner from studies dating back over a century, and provide an overview of ongoing research efforts that take advantage of this unique system.
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| 4. |
- Bououdina, M., et al.
(författare)
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Lithium storage in amorphous TiNi hydride : Electrode for rechargeable lithium-ion batteries
- 2013
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584 .- 1879-3312. ; 141:1, s. 348-354
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Tidskriftsartikel (refereegranskat)abstract
- In this study, amorphous TiNi phase was successfully prepared using mechanically milling for a very short time of 8 h. HRTEM confirms the formation of amorphous phase with the presence of nanocrystalline Fe particles. After hydrogenation (30 bars of H-2 for a duration of 2 h), the electrochemical reaction shows that TiNi hydride/Li cell discharges at a current of one Li for 10 h between 3 V and 0.005 V. The discharge of TiNiH electrode around x = 1 Li corresponds to a capacity of 251 mAh g(-1) and a hydride composition of TiNiH1.0 at an average voltage of 0.4 V. Ex-situ X-ray diffraction pattern collected at the end of the discharge shows a mixture of amorphous TiNi compound and LiH. A general mechanism for the electrochemical reaction is then proposed: alpha-TiNiH + Li+ + e(-) -> alpha-TiNi + LiH. The results from DFT calculations yield an average cell voltage of 0.396 V, which is in good agreement with the experimental pseudo-plateau occurring at 0.4 V.
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| 5. |
- Dupont, Chris L., et al.
(författare)
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Functional Tradeoffs Underpin Salinity-Driven Divergence in Microbial Community Composition
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:2, s. e89549-
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial community composition and functional potential change subtly across gradients in the surface ocean. In contrast, while there are significant phylogenetic divergences between communities from freshwater and marine habitats, the underlying mechanisms to this phylogenetic structuring yet remain unknown. We hypothesized that the functional potential of natural bacterial communities is linked to this striking divide between microbiomes. To test this hypothesis, metagenomic sequencing of microbial communities along a 1,800 km transect in the Baltic Sea area, encompassing a continuous natural salinity gradient from limnic to fully marine conditions, was explored. Multivariate statistical analyses showed that salinity is the main determinant of dramatic changes in microbial community composition, but also of large scale changes in core metabolic functions of bacteria. Strikingly, genetically and metabolically different pathways for key metabolic processes, such as respiration, biosynthesis of quinones and isoprenoids, glycolysis and osmolyte transport, were differentially abundant at high and low salinities. These shifts in functional capacities were observed at multiple taxonomic levels and within dominant bacterial phyla, while bacteria, such as SAR11, were able to adapt to the entire salinity gradient. We propose that the large differences in central metabolism required at high and low salinities dictate the striking divide between freshwater and marine microbiomes, and that the ability to inhabit different salinity regimes evolved early during bacterial phylogenetic differentiation. These findings significantly advance our understanding of microbial distributions and stress the need to incorporate salinity in future climate change models that predict increased levels of precipitation and a reduction in salinity.
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| 6. |
- Dupont, E., et al.
(författare)
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A phonon scattering assisted injection and extraction based terahertz quantum cascade laser
- 2012
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Ingår i: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 111:7
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Tidskriftsartikel (refereegranskat)abstract
- A lasing scheme for terahertz quantum cascade lasers, based on consecutive phonon-photon-phonon emissions per module, is proposed and experimentally demonstrated. The charge transport of the proposed structure is modeled using a rate equation formalism. An optimization code based on a genetic algorithm was developed to find a four-well design in the GaAs/Al0.25Ga0.75As material system that maximizes the product of population inversion and oscillator strength at 150 K. The fabricated devices using Au double-metal waveguides show lasing at 3.2 THz up to 138 K. The electrical characteristics display no sign of differential resistance drop at lasing threshold, which, in conjunction with the low optical power of the device, suggest-thanks to the rate equation model-a slow depopulation rate of the lower lasing state, a hypothesis confirmed by non-equilibrium Green's function calculations. [http://dx.doi.org/10.1063/1.3702571]
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| 7. |
- Dupont, Samuel, 1971, et al.
(författare)
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A snapshot of ocean acidification research
- 2013
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Ingår i: Marine Biology. ; 160:8, s. 1765-1771
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Forskningsöversikt (refereegranskat)abstract
- This special issue compiles 37 manuscripts investigating the biological impacts and societal relevance of ocean acidification. It includes important considerations regarding experimental design, new methods and how ocean acidification science can contribute to society through education and socioeconomic assessment. Altogether, this special issue constitutes a snapshot of recent ocean acidification research. This paper aims at summarizing the key findings and highlights future challenges and research priorities.
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| 8. |
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| 9. |
- Razavipour, S. G., et al.
(författare)
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An indirectly pumped terahertz quantum cascade laser with low injection coupling strength operating above 150 K
- 2013
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 113:20
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Tidskriftsartikel (refereegranskat)abstract
- We designed and demonstrated a terahertz quantum cascade laser based on indirect pump injection to the upper lasing state and phonon scattering extraction from the lower lasing state. By employing a rate equation formalism and a genetic algorithm, an optimized active region design with four-well GaAs/Al0.25Ga0.75As cascade module was obtained and epitaxially grown. A figure of merit which is defined as the ratio of modal gain versus injection current was maximized at 150 K. A fabricated device with a Au metal-metal waveguide and a top n(+) GaAs contact layer lased at 2.4 THz up to 128.5 K, while another one without the top n(+) GaAs lased up to 152.5 K (1.3 (h) over bar omega/k(B)). The experimental results have been analyzed with rate equation and nonequilibrium Green's function models. A high population inversion is achieved at high temperature using a small oscillator strength of 0.28, while its combination with the low injection coupling strength of 0.85 meV results in a low current. The carefully engineered wavefunctions enhance the quantum efficiency of the device and therefore improve the output optical power even with an unusually low injection coupling strength. (C) 2013 AIP Publishing LLC.
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