| 1. |
- Coustenis, A., et al.
(författare)
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TandEM : Titan and Enceladus mission
- 2009
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 23:3, s. 893-946
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Tidskriftsartikel (refereegranskat)abstract
- TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (MontgolfiSre) and possibly several landing probes to be delivered through the atmosphere.
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| 2. |
- Lammer, H., et al.
(författare)
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Geophysical and Atmospheric Evolution of Habitable Planets
- 2010
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Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 10:1, s. 45-68
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Tidskriftsartikel (refereegranskat)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. |
- Andersen, M. R., et al.
(författare)
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Comparative genomics of citric-acid-producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88
- 2011
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 21:6, s. 885-897
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Tidskriftsartikel (refereegranskat)abstract
- The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compel additional exploration. We therefore undertook wholegenome sequencing of the acidogenic A. niger wild-type strain (ATCC 1015) and produced a genome sequence of very high quality. Only 15 gaps are present in the sequence, and half the telomeric regions have been elucidated. Moreover, sequence information from ATCC 1015 was used to improve the genome sequence of CBS 513.88. Chromosome-level comparisons uncovered several genome rearrangements, deletions, a clear case of strain-specific horizontal gene transfer, and identification of 0.8 Mb of novel sequence. Single nucleotide polymorphisms per kilobase (SNPs/kb) between the two strains were found to be exceptionally high (average: 7.8, maximum: 160 SNPs/kb). High variation within the species was confirmed with exo-metabolite profiling and phylogenetics. Detailed lists of alleles were generated, and genotypic differences were observed to accumulate in metabolic pathways essential to acid production and protein synthesis. A transcriptome analysis supported up-regulation of genes associated with biosynthesis of amino acids that are abundant in glucoamylase A, tRNA-synthases, and protein transporters in the protein producing CBS 513.88 strain. Our results and data sets from this integrative systems biology analysis resulted in a snapshot of fungal evolution and will support further optimization of cell factories based on filamentous fungi
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| 4. |
- Grenfell, J. L., et al.
(författare)
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Co-Evolution of Atmospheres, Life, and Climate
- 2010
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Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 10:1, s. 77-88
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Tidskriftsartikel (refereegranskat)abstract
- After Earth's origin, our host star, the Sun, was shining 20-25% less brightly than today. Without greenhouse-like conditions to warm the atmosphere, our early planet would have been an ice ball, and life may never have evolved. But life did evolve, which indicates that greenhouse gases must have been present on early Earth to warm the planet. Evidence from the geological record indicates an abundance of the greenhouse gas CO2. CH4 was probably present as well; and, in this regard, methanogenic bacteria, which belong to a diverse group of anaerobic prokaryotes that ferment CO2 plus H-2 to CH4, may have contributed to modification of the early atmosphere. Molecular oxygen was not present, as is indicated by the study of rocks from that era, which contain iron carbonate rather than iron oxide. Multicellular organisms originated as cells within colonies that became increasingly specialized. The development of photosynthesis allowed the Sun's energy to be harvested directly by life-forms. The resultant oxygen accumulated in the atmosphere and formed the ozone layer in the upper atmosphere. Aided by the absorption of harmful UV radiation in the ozone layer, life colonized Earth's surface. Our own planet is a very good example of how life-forms modified the atmosphere over the planets' lifetime. We show that these facts have to be taken into account when we discover and characterize atmospheres of Earth-like exoplanets. If life has originated and evolved on a planet, then it should be expected that a strong co-evolution occurred between life and the atmosphere, the result of which is the planet's climate.
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| 5. |
- Nooijen, Carla F., et al.
(författare)
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Fatigue in persons with subacute spinal cord injury who are dependent on a manual wheelchair
- 2015
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Ingår i: Spinal Cord. - : Springer Science and Business Media LLC. - 1362-4393 .- 1476-5624. ; 53:10, s. 758-62
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: Cross-sectional. OBJECTIVES: To determine the prevalence and severity of fatigue in persons with subacute spinal cord injury (SCI), assess whether demographic and lesion characteristics are related to fatigue and determine the relationship with physical fitness and physical behavior. SETTING: Measurements were performed 2 months before discharge from inpatient rehabilitation. METHODS: Thirty-six persons with subacute SCI, dependent on a manual wheelchair, mean age 43+/-15 and 83% men, completed the Fatigue Severity Scale (FSS). FSS scores >4 indicated fatigue. We recorded age and lesion characteristics, measured body mass index, measured peak power output and peak oxygen uptake during a maximal handcycling test and determined physical behavior using an accelerometer-based activity monitor. T-tests were used to test for differences in fatigue between subgroups based on age and lesion characteristics, and regression analyses to assess the relationship with physical fitness and physical behavior. RESULTS: Mean FSS was 3.3+/-1.3. Fatigue, including severe fatigue, was prevalent in 31% (95% confidence interval: 16-46) of participants compared with 18% in the general population. Furthermore, mean fatigue was significantly higher in persons with incomplete compared with complete lesions (t=2.22, P=0.03). Mean scores between other subgroups did not differ significantly. Of the physical fitness and physical behavior measures, only peak oxygen uptake tended to be related to more fatigue (B=-1.47, P=0.05). CONCLUSION: Fatigue was prevalent and is of concern in persons with subacute SCI. Those with incomplete lesions seem to be at higher risk. Because fatigue is known to persist among persons with SCI, interventions to reduce fatigue seem necessary.
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| 6. |
- Patty, C. H.Lucas, et al.
(författare)
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Biosignatures of the Earth : I. Airborne spectropolarimetric detection of photosynthetic life
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 651
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Tidskriftsartikel (refereegranskat)abstract
- Context. Homochirality is a generic and unique property of life on Earth and is considered a universal and agnostic biosignature. Homochirality induces fractional circular polarization in the incident light that it reflects. Because this circularly polarized light can be sensed remotely, it can be one of the most compelling candidate biosignatures in life detection missions. While there are also other sources of circular polarization, these result in spectrally flat signals with lower magnitude. Additionally, circular polarization can be a valuable tool in Earth remote sensing because the circular polarization signal directly relates to vegetation physiology. Aims. While high-quality circular polarization measurements can be obtained in the laboratory and under semi-static conditions in the field, there has been a significant gap to more realistic remote sensing conditions. Methods. In this study, we present sensitive circular spectropolarimetric measurements of various landscape elements taken from a fast-moving helicopter. Results. We demonstrate that during flight, within mere seconds of measurements, we can differentiate (S∕ N > 5) between grass fields, forests, and abiotic urban areas. Importantly, we show that with only nonzero circular polarization as a discriminant, photosynthetic organisms can even be measured in lakes. Conclusions. Circular spectropolarimetry can be a powerful technique to detect life beyond Earth, and we emphasize the potential of utilizing circular spectropolarimetry as a remote sensing tool to characterize and monitor in detail the vegetation physiology and terrain features of Earth itself.
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| 7. |
- van den Berg-Emons, R. J., et al.
(författare)
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Fatigue after liver transplantation : effects of a rehabilitation program including exercise training and physical activity counseling
- 2014
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Ingår i: Physical Therapy. - : Oxford University Press (OUP). - 0031-9023 .- 1538-6724. ; 94:6, s. 857-65
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: It is hypothesized that increasing physical fitness and daily physical activity can lead to a reduction in fatigue. However, standard medical care following liver transplantation seldom includes rehabilitation that focuses on physical fitness and physical activity. OBJECTIVE: The aim of this study was to explore whether a rehabilitation program can reduce fatigue in recipients of liver transplants. Furthermore, effects on physical fitness, physical activity, and cardiovascular risk were studied, and adherence, satisfaction, and adverse events were assessed. DESIGN: This was an uncontrolled intervention study. SETTING: The study took place in an outpatient rehabilitation clinic. PATIENTS: Eighteen recipients of a liver transplant who were fatigued participated in a 12-week rehabilitation program including physical exercise training and counseling on physical activity. The primary outcome measure was fatigue. Other outcome measures were: aerobic capacity, muscle strength, body fat, daily physical activity, lipid profile, and glycemic control. All measurements were performed before and after the rehabilitation program. Adherence, satisfaction, and adverse events were registered. RESULTS: After the program, participants were significantly less fatigued, and the percentage of individuals with severe fatigue was 22% to 53% lower than before the program. In addition, aerobic capacity and knee flexion strength were significantly higher, and body fat was significantly lower after the program. Participants were able to perform physical exercise at the target training intensity, no adverse events were registered, and attendance (93%) and mean patient satisfaction (8.5 out of 10, range=7-10) were high. LIMITATIONS: No control group was used in the study. CONCLUSIONS: A rehabilitation program consisting of exercise training and physical activity counseling is well tolerated and seems promising in reducing fatigue and improving fitness among recipients of liver transplants.
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| 8. |
- Alibert, Y., et al.
(författare)
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Origin and Formation of Planetary Systems
- 2010
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Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 10:1, s. 19-32
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Tidskriftsartikel (refereegranskat)abstract
- To estimate the occurrence of terrestrial exoplanets and maximize the chance of finding them, it is crucial to understand the formation of planetary systems in general and that of terrestrial planets in particular. We show that a reliable formation theory should not only explain the formation of the Solar System, with small terrestrial planets within a few AU and gas giants farther out, but also the newly discovered exoplanetary systems with close-in giant planets. Regarding the presently known exoplanets, we stress that our current knowledge is strongly biased by the sensitivity limits of current detection techniques (mainly the radial velocity method). With time and improved detection methods, the diversity of planets and orbits in exoplanetary systems will definitely increase and help to constrain the formation theory further. In this work, we review the latest state of planetary formation in relation to the origin and evolution of habitable terrestrial planets.
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| 9. |
- Brack, A., et al.
(författare)
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Origin and Evolution of Life on Terrestrial Planets
- 2010
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Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 10:1, s. 69-76
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Tidskriftsartikel (refereegranskat)abstract
- The ultimate goal of terrestrial planet-finding missions is not only to discover terrestrial exoplanets inside the habitable zone (HZ) of their host stars but also to address the major question as to whether life may have evolved on a habitable Earth-like exoplanet outside our Solar System. We note that the chemical evolution that finally led to the origin of life on Earth must be studied if we hope to understand the principles of how life might evolve on other terrestrial planets in the Universe. This is not just an anthropocentric point of view: the basic ingredients of terrestrial life, that is, reduced carbon-based molecules and liquid H2O, have very specific properties. We discuss the origin of life from the chemical evolution of its precursors to the earliest life-forms and the biological implications of the stellar radiation and energetic particle environments. Likewise, the study of the biological evolution that has generated the various life-forms on Earth provides clues toward the understanding of the interconnectedness of life with its environment.
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| 10. |
- Dvorak, R., et al.
(författare)
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Dynamical Habitability of Planetary Systems
- 2010
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Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 10:1, s. 33-43
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Tidskriftsartikel (refereegranskat)abstract
- The problem of the stability of planetary systems, a question that concerns only multiplanetary systems that host at least two planets, is discussed. The problem of mean motion resonances is addressed prior to discussion of the dynamical structure of the more than 350 known planets. The difference with regard to our own Solar System with eight planets on low eccentricity is evident in that 60% of the known extrasolar planets have orbits with eccentricity e > 0.2. We theoretically highlight the studies concerning possible terrestrial planets in systems with a Jupiter-like planet. We emphasize that an orbit of a particular nature only will keep a planet within the habitable zone around a host star with respect to the semimajor axis and its eccentricity. In addition, some results are given for individual systems (e.g., Gl777A) with regard to the stability of orbits within habitable zones. We also review what is known about the orbits of planets in double-star systems around only one component ( e. g., gamma Cephei) and around both stars (e.g., eclipsing binaries).
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