| 1. |
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| 2. |
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| 3. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 4. |
- Korablev, O., et al.
(författare)
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The Atmospheric Chemistry Suite (ACS) of Three Spectrometers for the ExoMars 2016 Trace Gas Orbiter
- 2018
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Ingår i: Space Science Reviews. - : Springer. - 0038-6308 .- 1572-9672. ; 214:1
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Tidskriftsartikel (refereegranskat)abstract
- The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm−1. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described.
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| 5. |
- Freissinet, C., et al.
(författare)
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Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars
- 2015
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 120:3, s. 495-514
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Tidskriftsartikel (refereegranskat)abstract
- The Sample Analysis at Mars (SAM) instrument [Mahaffy et al., 2012] onboard the Mars Science Laboratory (MSL) Curiosity rover is designed to conduct inorganic and organic chemical analyses of the atmosphere and the surface regolith and rocks to help evaluate the past and present habitability potential of Mars at Gale Crater [Grotzinger et al., 2012]. Central to this task is the development of an inventory of any organic molecules present to elucidate processes associated with their origin, diagenesis, concentration and long-term preservation. This will guide the future search for biosignatures [Summons et al., 2011]. Here we report the definitive identification of chlorobenzene (150–300 parts per billion by weight (ppbw)) and C2 to C4 dichloroalkanes (up to 70 ppbw) with the SAM gas chromatograph mass spectrometer (GCMS), and detection of chlorobenzene in the direct evolved gas analysis (EGA) mode, in multiple portions of the fines from the Cumberland drill hole in the Sheepbed mudstone at Yellowknife Bay. When combined with GCMS and EGA data from multiple scooped and drilled samples, blank runs and supporting laboratory analog studies, the elevated levels of chlorobenzene and the dichloroalkanes cannot be solely explained by instrument background sources known to be present in SAM. We conclude that these chlorinated hydrocarbons are the reaction products of martian chlorine and organic carbon derived from martian sources (e.g. igneous, hydrothermal, atmospheric, or biological) or exogenous sources such as meteorites, comets or interplanetary dust particles.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Vaughan, A., et al.
(författare)
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Regolith of the Crater Floor Units, Jezero Crater, Mars : Textures, Composition, and Implications for Provenance
- 2023
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Ingår i: Journal of Geophysical Research - Planets. - : John Wiley and Sons Inc. - 2169-9097 .- 2169-9100. ; 128:3
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Tidskriftsartikel (refereegranskat)abstract
- A multi-instrument study of the regolith of Jezero crater floor units by the Perseverance rover has identified three types of regolith: fine-grained, coarse-grained, and mixed-type. Mastcam-Z, Wide Angle Topographic Sensor for Operations and eNgineering, and SuperCam Remote Micro Imager were used to characterize the regolith texture, particle size, and roundedness where possible. Mastcam-Z multispectral and SuperCam laser-induced breakdown spectroscopy data were used to constrain the composition of the regolith types. Fine-grained regolith is found surrounding bedrock and boulders, comprising bedforms, and accumulating on top of rocks in erosional depressions. Spectral and chemical data show it is compositionally consistent with pyroxene and a ferric-oxide phase. Coarse-grained regolith consists of 1–2 mm well-sorted gray grains that are found concentrated around the base of boulders and bedrock, and armoring bedforms. Its chemistry and spectra indicate it is olivine-bearing, and its spatial distribution and roundedness indicate it has been transported, likely by saltation-induced creep. Coarse grains share similarities with the olivine grains observed in the Séítah formation bedrock, making that unit a possible source for these grains. Mixed-type regolith contains fine- and coarse-grained regolith components and larger rock fragments. The rock fragments are texturally and spectrally similar to bedrock within the Máaz and Séítah formations, indicating origins by erosion from those units, although they could also be a lag deposit from erosion of an overlying unit. The fine- and coarse-grained types are compared to their counterparts at other landing sites to inform global, regional, and local inputs to regolith formation within Jezero crater. The regolith characterization presented here informs the regolith sampling efforts underway by Perseverance. © 2023. The Authors.
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| 10. |
- Conrad, P.G., et al.
(författare)
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Environmental Dynamics and the Habitability Potential at Gale Crater, Mars
- 2013
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Konferensbidrag (refereegranskat)abstract
- The assessment of environmental habitability potential involves measurement of the chemical and physical attributes of the system as well as their dynamic interplay. The environmental dynamics describe the availability of both energy sources and raw materials for meeting the requirements of organisms and for altering the environment. Energetic exchange can also determine the preservation potential for organic materials in the rock record. During its first year at Gale Crater, the Mars Science Laboratory payload has directly measured the chemistry and physical attributes, e.g., temperature, humidity, radiation, pressure, etc. of the martian atmosphere. Curiosity has also acquired chemical and mineralogical data, both from a wind drift deposit of fines and from two examples of a sedimentary rock formation in a region of Gale Crater called Yellowknife Bay, some 445 meters to the east of Bradbury Landing, where Curiosity initially touched down. These data enabled inferences to be made regarding depositional environment and past habitability potential at Gale Crater. The rock chemistry data reveal signs of aqueous interaction i.e., H2O, OH and H2 and sufficient elemental basis (C, H, O, S and possibly N) for plausible nutrient supply, should Mars have ever had autotrophic prokaryotes to exploit it, and a range of redox conditions tolerable to Earth microbes is indicated by the presence of clay minerals. Curiosity’s observations of the chemical, physical and geologic features of Yellowknife Bay point to a formerly habitable environment.
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| 11. |
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| 12. |
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| 13. |
- Gómez-Elvira, J., et al.
(författare)
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REMS : The environmental sensor suite for the Mars Science Laboratory rover
- 2012
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Ingår i: Space Science Reviews. - : Springer Science and Business Media LLC. - 0038-6308 .- 1572-9672. ; 170:1-4, s. 583-640
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Tidskriftsartikel (refereegranskat)abstract
- The Rover Environmental Monitoring Station (REMS) will investigate environmental factors directly tied to current habitability at the Martian surface during the Mars Science Laboratory (MSL) mission. Three major habitability factors are addressed by REMS: the thermal environment, ultraviolet irradiation, and water cycling. The thermal environment is determined by a mixture of processes, chief amongst these being the meteorological. Accordingly, the REMS sensors have been designed to record air and ground temperatures, pressure, relative humidity, wind speed in the horizontal and vertical directions, as well as ultraviolet radiation in different bands. These sensors are distributed over the rover in four places: two booms located on the MSL Remote Sensing Mast, the ultraviolet sensor on the rover deck, and the pressure sensor inside the rover body. Typical daily REMS observations will collect 180 minutes of data from all sensors simultaneously (arranged in 5 minute hourly samples plus 60 additional minutes taken at times to be decided during the course of the mission). REMS will add significantly to the environmental record collected by prior missions through the range of simultaneous observations including water vapor; the ability to take measurements routinely through the night; the intended minimum of one Martian year of observations; and the first measurement of surface UV irradiation. In this paper, we describe the scientific potential of REMS measurements and describe in detail the sensors that constitute REMS and the calibration procedures. © 2012 Springer Science+Business Media B.V.
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| 14. |
- Guzewich, Scott D., et al.
(författare)
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Mars Science Laboratory Observations of the 2018/Mars Year 34 Global Dust Storm
- 2019
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 46:1, s. 71-79
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Tidskriftsartikel (refereegranskat)abstract
- Mars Science Laboratory Curiosity rover observations of the 2018/Mars year 34 global/planet‐encircling dust storm represent the first in situ measurements of a global dust storm with dedicated meteorological sensors since the Viking Landers. The Mars Science Laboratory team planned and executed a science campaign lasting approximately 100 Martian sols to study the storm involving an enhanced cadence of environmental monitoring using the rover's meteorological sensors, cameras, and spectrometers. Mast Camera 880‐nm optical depth reached 8.5, and Rover Environmental Monitoring Station measurements indicated a 97% reduction in incident total ultraviolet solar radiation at the surface, 30K reduction in diurnal range of air temperature, and an increase in the semidiurnal pressure tide amplitude to 40 Pa. No active dust‐lifting sites were detected within Gale Crater, and global and local atmospheric dynamics were drastically altered during the storm. This work presents an overview of the mission's storm observations and initial results.
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| 15. |
- Haberle, R. M., et al.
(författare)
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Preliminary interpretation of the REMS pressure data from the first 100 sols of the MSL mission
- 2014
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Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 119:3, s. 440-453
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Tidskriftsartikel (refereegranskat)abstract
- We provide a preliminary interpretation of the Rover Environmental Monitoring Station (REMS) pressure data from the first 100 Martian solar days (sols) of the Mars Science Laboratory mission. The pressure sensor is performing well and has revealed the existence of phenomena undetected by previous missions that include possible gravity waves excited by evening downslope flows, relatively dust-free convective vortices analogous in structure to dust devils, and signatures indicative of the circulation induced by Gale Crater and its central mound. Other more familiar phenomena are also present including the thermal tides, generated by daily insolation variations, and the CO2 cycle, driven by the condensation and sublimation of CO2 in the polar regions. The amplitude of the thermal tides is several times larger than those seen by other landers primarily because Curiosity is located where eastward and westward tidal modes constructively interfere and also because the crater circulation amplifies the tides to some extent. During the first 100 sols tidal amplitudes generally decline, which we attribute to the waning influence of the Kelvin wave. Toward the end of the 100 sol period, tidal amplitudes abruptly increased in response to a nearby regional dust storm that did not expand to global scales. Tidal phases changed abruptly during the onset of this storm suggesting a change in the interaction between eastward and westward modes. When compared to Viking Lander 2 data, the REMS daily average pressures show no evidence yet for the 1-20 Pa increase expected from the possible loss of CO 2 from the south polar residual cap. Key Points REMS pressure sensor is operating nominally New phenomena have been discovered Familiar phenomena have been detected ©2014. American Geophysical Union. All Rights Reserved.
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| 16. |
- Harri, A.-M., et al.
(författare)
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Pressure observations by the Curiosity rover : Initial results
- 2014
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Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 119:1, s. 82-92
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Tidskriftsartikel (refereegranskat)abstract
- REMS-P, the pressure measurement subsystem of the Mars Science Laboratory (MSL) Rover Environmental Measurement Station (REMS), is performing accurate observations of the Martian atmospheric surface pressure. It has demonstrated high data quality and good temporal coverage, carrying out the first in situ pressure observations in the Martian equatorial regions. We describe the REMS-P initial results by MSL mission sol 100 including the instrument performance and data quality and illustrate some initial interpretations of the observed features. The observations show both expected and new phenomena at various spatial and temporal scales, e.g., the gradually increasing pressure due to the advancing Martian season signals from the diurnal tides as well as various local atmospheric phenomena and thermal vortices. Among the unexpected new phenomena discovered in the pressure data are a small regular pressure drop at every sol and pressure oscillations occurring in the early evening. We look forward to continued high-quality observations by REMS-P, extending the data set to reveal characteristics of seasonal variations and improved insights into regional and local phenomena. Key Points The performance and data quality of the REMS / MSL pressure observations. MSL pressure observations exhibit local phenomena of the Gale crater area. Small pressure oscillations possibly linked to gravity waves. ©2013. American Geophysical Union. All Rights Reserved.
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| 17. |
- Korablev, Oleg I., et al.
(författare)
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Infrared Spectrometer for ExoMars: A Mast-Mounted Instrument for the Rover
- 2017
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Ingår i: Astrobiology. - : Mary Ann Liebert. - 1531-1074 .- 1557-8070. ; 17:6-7, s. 542-564
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Tidskriftsartikel (refereegranskat)abstract
- ISEM (Infrared Spectrometer for ExoMars) is a pencil-beam infrared spectrometer that will measure reflected solar radiation in the near infrared range for context assessment of the surface mineralogy in the vicinity of the ExoMars rover. The instrument will be accommodated on the mast of the rover and will be operated together with the panoramic camera (PanCam), high-resolution camera (HRC). ISEM will study the mineralogical and petrographic composition of the martian surface in the vicinity of the rover, and in combination with the other remote sensing instruments, it will aid in the selection of potential targets for close-up investigations and drilling sites. Of particular scientific interest are water-bearing minerals, such as phyllosilicates, sulfates, carbonates, and minerals indicative of astrobiological potential, such as borates, nitrates, and ammonium-bearing minerals. The instrument has an ∼1° field of view and covers the spectral range between 1.15 and 3.30 μm with a spectral resolution varying from 3.3 nm at 1.15 μm to 28 nm at 3.30 μm. The ISEM optical head is mounted on the mast, and its electronics box is located inside the rover's body. The spectrometer uses an acousto-optic tunable filter and a Peltier-cooled InAs detector. The mass of ISEM is 1.74 kg, including the electronics and harness. The science objectives of the experiment, the instrument design, and operational scenarios are described.
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| 18. |
- Romero, M., et al.
(författare)
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TP53INP2 regulates adiposity by activating β-catenin through autophagy-dependent sequestration of GSK3β
- 2018
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Ingår i: Nature Cell Biology. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 20:4, s. 443-454
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Tidskriftsartikel (refereegranskat)abstract
- Excessive fat accumulation is a major risk factor for the development of type 2 diabetes mellitus and other common conditions, including cardiovascular disease and certain types of cancer. Here, we identify a mechanism that regulates adiposity based on the activator of autophagy TP53INP2. We report that TP53INP2 is a negative regulator of adipogenesis in human and mouse preadipocytes. In keeping with this, TP53INP2 ablation in mice caused enhanced adiposity, which was characterized by greater cellularity of subcutaneous adipose tissue and increased expression of master adipogenic genes. TP53INP2 modulates adipogenesis through autophagy-dependent sequestration of GSK3β into late endosomes. GSK3β sequestration was also dependent on ESCRT activity. As a result, TP53INP2 promotes greater β-catenin levels and induces the transcriptional activity of TCF/LEF transcription factors. These results demonstrate a link between autophagy, sequestration of GSK3β into late endosomes and inhibition of adipogenesis in vivo. © 2018 The Author(s).
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| 19. |
- Webster, Christopher R., et al.
(författare)
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Mars methane detection and variability at Gale crater
- 2015
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 347:6220, s. 415-417
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Tidskriftsartikel (refereegranskat)abstract
- Reports of plumes or patches of methane in the Martian atmosphere that vary over monthly timescales have defied explanation to date. From in situ measurements made over a 20-month period by the Tunable Laser Spectrometer (TLS) of the Sample Analysis at Mars (SAM) instrument suite on Curiosity at Gale Crater, we report detection of background levels of atmospheric methane of mean value 0.69 ± 0.25 ppbv at the 95% confidence interval (CI). This abundance is lower than model estimates of ultraviolet (UV) degradation of accreted interplanetary dust particles (IDP’s) or carbonaceous chondrite material. Additionally, in four sequential measurements spanning a 60-sol period, we observed elevated levels of methane of 7.2 ± 2.1 (95% CI) ppbv implying that Mars is episodically producing methane from an additional unknown source.
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| 20. |
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| 21. |
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| 22. |
- Lanza, Nina L., et al.
(författare)
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Oxidation of manganese in an ancient aquifer, Kimberley formation, Gale crater, Mars
- 2016
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 43:14, s. 7398-7407
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Tidskriftsartikel (refereegranskat)abstract
- The Curiosity rover observed high Mn abundances (>25wt % MnO) in fracture-filling materials that crosscut sandstones in the Kimberley region of Gale crater, Mars. The correlation between Mn and trace metal abundances plus the lack of correlation between Mn and elements such as S, Cl, and C, reveals that these deposits are Mn oxides rather than evaporites or other salts. On Earth, environments that concentrate Mn and deposit Mn minerals require water and highly oxidizing conditions; hence, these findings suggest that similar processes occurred on Mars. Based on the strong association between Mn-oxide deposition and evolving atmospheric dioxygen levels on Earth, the presence of these Mn phases on Mars suggests that there was more abundant molecular oxygen within the atmosphere and some groundwaters of ancient Mars than in the present day
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| 23. |
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| 24. |
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| 25. |
- Rodriguez-Cuenca, S., et al.
(författare)
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Allostatic hypermetabolic response in PGC1 alpha/beta heterozygote mouse despite mitochondrial defects
- 2021
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Ingår i: Faseb Journal. - 0892-6638. ; 35:9
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Tidskriftsartikel (refereegranskat)abstract
- Aging, obesity, and insulin resistance are associated with low levels of PGC1 alpha and PGC1 beta coactivators and defective mitochondrial function. We studied mice deficient for PGC1 alpha and PGC1 beta [double heterozygous (DH)] to investigate their combined pathogenic contribution. Contrary to our hypothesis, DH mice were leaner, had increased energy dissipation, a pro-thermogenic profile in BAT and WAT, and improved carbohydrate metabolism compared to wild types. WAT showed upregulation of mitochondriogenesis/oxphos machinery upon allelic compensation of PGC1 alpha 4 from the remaining allele. However, DH mice had decreased mitochondrial OXPHOS and biogenesis transcriptomes in mitochondria-rich organs. Despite being metabolically healthy, mitochondrial defects in DH mice impaired muscle fiber remodeling and caused qualitative changes in the hepatic lipidome. Our data evidence first the existence of organ-specific compensatory allostatic mechanisms are robust enough to drive an unexpected phenotype. Second, optimization of adipose tissue bioenergetics is sufficient to maintain a healthy metabolic phenotype despite a broad severe mitochondrial dysfunction in other relevant metabolic organs. Third, the decrease in PGC1s in adipose tissue of obese and diabetic patients is in contrast with the robustness of the compensatory upregulation in the adipose of the DH mice.
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| 26. |
- Vandaele, Ann Carine, et al.
(författare)
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Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter
- 2019
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Ingår i: Nature. - : Springer. - 1476-4687 .- 1476-4687 .- 0028-0836. ; 568:7753, s. 521-525
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.
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| 27. |
- Ahlin, Sofie, 1985, et al.
(författare)
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Metabolite Changes After Metabolic Surgery – Associations to Parameters Reflecting Glucose Homeostasis and Lipid Levels
- 2021
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Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To test the hypothesis that adipose tissue gene expression patterns would be affected by metabolic surgery and we aimed to identify genes and metabolic pathways as well as metabolites correlating with metabolic changes following metabolic surgery. Materials and Methods: This observational study was conducted at the Obesity Unit at the Catholic University Hospital of the Sacred Heart in Rome, Italy. Fifteen patients, of which six patients underwent Roux-en-Y gastric bypass and nine patients underwent biliopancreatic diversion, were included. The participants underwent an oral glucose tolerance test and a hyperinsulinemic euglycemic clamp. Small polar metabolites were analyzed with a two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS). Gene expression analysis of genes related to metabolism of amino acids and fatty acids were analyzed in subcutaneous adipose tissue. All procedures were performed at study start and at follow-up (after 185.3 ± 72.9 days). Results: Twelve metabolites were significantly changed after metabolic surgery. Six metabolites were identified as 3-indoleacetic acid, 2-hydroxybutyric acid, valine, glutamic acid, 4-hydroxybenzeneacetic acid and alpha-tocopherol. The branched chain amino acids displayed a significant decrease together with a decrease in BCAT1 adipose tissue mRNA levels. Changes in the identified metabolites were associated to changes in lipid, insulin and glucose levels. Conclusions: Our study has identified metabolites and metabolic pathways that are altered by metabolic surgery and may be used as biomarkers for metabolic improvement. Copyright © 2021 Ahlin, Cefalo, Bondia-Pons, Trošt, Capristo, Marini, Romero, Zorzano, Gastaldelli, Mingrone and Nolan.
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| 28. |
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| 29. |
- Enrique-Tarancon, G, et al.
(författare)
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Substrates of semicarbazide-sensitive amine oxidase co-operate with vanadate to stimulate tyrosine phosphorylation of insulin-receptor-substrate proteins, phosphoinositide 3-kinase activity and GLUT4 translocation in adipose cells
- 2000
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Ingår i: Biochemical Journal. - 0264-6021. ; 350:1, s. 171-180
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Tidskriftsartikel (refereegranskat)abstract
- It has been shown that the combination of benzylamine or tyramine and low concentrations of vanadate markedly stimulates glucose transport in rat adipocytes by a mechanism that requires semicarbazide-sensitive amine oxidase (SSAO) activity and H(2)O(2) formation. Here we have further analysed the insulin-like effects of the combination of SSAO substrates and vanadate and we have studied the signal-transduction pathway activated in rat adipocytes. We found that several SSAO substrates (benzylamine, tyramine, methylamine, n-decylamine, histamine, tryptamine or beta-phenylethylamine), in combination with low concentrations of vanadate, stimulate glucose transport in isolated rat adipocytes. Furthermore, SSAO substrates together with vanadate stimulated the recruitment of GLUT4 to the cell surface in isolated rat adipocytes. Benzylamine plus vanadate also stimulated glucose transport and GLUT4 translocation in 3T3-L1 adipocytes. Benzylamine or tyramine in combination with vanadate potently stimulated the tyrosine phosphorylation of both insulin receptor substrate (IRS)-1 and IRS-3. In contrast, benzylamine and vanadate caused only a weak stimulation of insulin receptor kinase. Benzylamine or tyramine in combination with vanadate also stimulated phosphoinositide 3-kinase activity; wortmannin abolished the stimulatory effect of benzylamine and vanadate on glucose transport in adipose cells. Furthermore, the administration of benzylamine and vanadate in vivo caused a rapid lowering of plasma glucose levels, which took place in the absence of alterations in plasma insulin. On the basis of these results we propose that SSAO activity regulates glucose transport in adipocytes. SSAO oxidative activity stimulates glucose transport via the translocation of GLUT4 carriers to the cell surface, resulting from a potent tyrosine phosphorylation of IRS-1 and IRS-3 and phosphoinositide 3-kinase activation. Our results also indicate that substrates of SSAO might regulate glucose disposal in vivo.
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| 30. |
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| 31. |
- Gõmez-Elvira, Javier, et al.
(författare)
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Curiosity's rover environmental monitoring station : Overview of the first 100 sols
- 2014
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 119:7, s. 1680-1688
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Tidskriftsartikel (refereegranskat)abstract
- In the first 100 Martian solar days (sols) of the Mars Science Laboratory mission, the Rover Environmental Monitoring Station (REMS) measured the seasonally evolving diurnal cycles of ultraviolet radiation, atmospheric pressure, air temperature, ground temperature, relative humidity, and wind within Gale Crater on Mars. As an introduction to several REMS-based articles in this issue, we provide an overview of the design and performance of the REMS sensors and discuss our approach to mitigating some of the difficulties we encountered following landing, including the loss of one of the two wind sensors. We discuss the REMS data set in the context of other Mars Science Laboratory instruments and observations and describe how an enhanced observing strategy greatly increased the amount of REMS data returned in the first 100 sols, providing complete coverage of the diurnal cycle every 4 to 6 sols. Finally, we provide a brief overview of key science results from the first 100 sols. We found Gale to be very dry, never reaching saturation relative humidities, subject to larger diurnal surface pressure variations than seen by any previous lander on Mars, air temperatures consistent with model predictions and abundant short timescale variability, and surface temperatures responsive to changes in surface properties and suggestive of subsurface layering. Key Points Introduction to the REMS results on MSL mission Overiview of the sensor information Overview of operational constraints
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| 32. |
- Guma, A, et al.
(författare)
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Emerging role of neuregulin as a modulator of muscle metabolism
- 2010
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 298:4, s. E742-E750
-
Tidskriftsartikel (refereegranskat)abstract
- Neuregulin was described initially as a neurotrophic factor involved in the formation of the neuromuscular junction in skeletal muscle. However, in recent years, neuregulin has been reported to be a myokine that exerts relevant effects on myogenesis and the regulation of muscle metabolism. In this new context, the rapid and chronic metabolic effects of neuregulin appear to be related to muscle contraction. Indeed, the effects of neuregulin resemble those of exercise, which are accompanied by an improvement in insulin sensitivity. In this review, we challenge the classical role assigned to neuregulin in muscle and propound the emerging concept of its involvement in the regulation of energetic metabolism and insulin responsiveness.
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| 33. |
- Harri, A.-M., et al.
(författare)
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Mars Science Laboratory relative humidity observations : Initial results
- 2014
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 119:9, s. 2132-2147
-
Tidskriftsartikel (refereegranskat)abstract
- The Mars Science Laboratory (MSL) made a successful landing at Gale crater early August 2012. MSL has an environmental instrument package called the Rover Environmental Monitoring Station (REMS) as a part of its scientific payload. REMS comprises instrumentation for the observation of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity (REMS-H), and UV measurements. We concentrate on describing the REMS-H measurement performance and initial observations during the first 100 MSL sols as well as constraining the REMS-H results by comparing them with earlier observations and modeling results. The REMS-H device is based on polymeric capacitive humidity sensors developed by Vaisala Inc., and it makes use of transducer electronics section placed in the vicinity of the three humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The final relative humidity results appear to be convincing and are aligned with earlier indirect observations of the total atmospheric precipitable water content. The water mixing ratio in the atmospheric surface layer appears to vary between 30 and 75 ppm. When assuming uniform mixing, the precipitable water content of the atmosphere is ranging from a few to six precipitable micrometers.
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| 34. |
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| 35. |
- Lasue, J., et al.
(författare)
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Martian Eolian Dust Probed by ChemCam
- 2018
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Ingår i: Geophysical Research Letters. - : John Wiley & Sons. - 0094-8276 .- 1944-8007. ; 45:20, s. 10968-10977
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Tidskriftsartikel (refereegranskat)abstract
- The ubiquitous eolian dust on Mars plays important roles in the current sedimentary and atmospheric processes of the planet. The ChemCam instrument retrieves a consistent eolian dust composition at the submillimeter scale from every first laser shot on Mars targets. Its composition presents significant differences with the Aeolis Palus soils and the Bagnold dunes as it contains lower CaO and higher SiO2. The dust FeO and TiO2contents are also higher, probably associated with nanophase oxide components. The dust spectra show the presence of volatile elements (S and Cl), and the hydrogen content is similar to Bagnold sands but lower than Aeolis Palus soils. Consequently, the dust may be a contributor to the amorphous component of soils, but differences in composition indicate that the two materials are not equivalent.
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| 36. |
- Renno, N.O., et al.
(författare)
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Ground-atmosphere interactions at Gale
- 2013
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Konferensbidrag (refereegranskat)abstract
- We analyze variations in environmental parameters and regolith properties along Curiosity’s track to determine the possible causes of an abrupt change in the thermal properties of the ground and the atmosphere observed around Sol 120, as the rover transitioned from an area of sandy soil (Rocknest) to an area of fractured bedrock terrain (Yellowknife). Curiosity is instrumented with the Rover Environmental Monitoring Station (REMS) and the Dynamic Albedo of Neutrons (DAN) sensors to measure the air temperature, the ground temperature, and the hydrogen content of the shallow subsurface along Curiosity’s track. Analysis of the REMS data is used to estimate the regolith’s heat budget. This analysis suggests that the abrupt decrease in the ground and atmosphere temperature and the difference between ground and air temperatures observed around Sol 120 is likely caused by an increase in the soil thermal inertia. The changes in thermal inertia have been known for some time so confirming this by the REMS package provides ground truthing. A new unexpected finding is that the regolith water content, as indicated by DAN’s detection of hydrogen content, is higher in the Yellowknife soil. Another interesting finding at this site are the holes and other signs of recent geological activity in the area of fractured terrain that may reflect large volumetric variations and facilitate gas exchange between the ground and atmosphere. Near-surface volumetric changes in soil and bedrock could reflect changes in the volume of subsurface H2O, or in the partitioning of H2O among its three phases. Volume increases could also result from salt crystal growth in rock pores and soil pores associated with the adsorption of water vapor. Crystallization in pores is a significant weathering process on Earth; it could well be active on Mars. Salts also inhibits the exchange of moisture between the ground and the atmosphere, and cements the soils of arid places such as in the McMurdo Dry Valleys in Antarctica. Indeed, salts might be responsible for the ubiquitous martian duricrust. More importantly, salt crusts have the potential to create pockets of wet regolith in the shallow martian subsurface that could be habitable. A better understanding of ground-atmosphere interactions has the potential to shed new light into aqueous processes in the shallow martian subsurface.
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| 37. |
- Bach, D, et al.
(författare)
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Expression of Mfn2, the Charcot-Marie-Tooth neuropathy type 2A gene, in human skeletal muscle: effects of type 2 diabetes, obesity, weight loss, and the regulatory role of tumor necrosis factor alpha and interleukin-6
- 2005
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 54:9, s. 2685-2693
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Tidskriftsartikel (refereegranskat)abstract
- The primary gene mutated in Charcot-Marie-Tooth type 2A is mitofusin-2 (Mfn2). Mfn2 encodes a mitochondrial protein that participates in the maintenance of the mitochondrial network and that regulates mitochondrial metabolism and intracellular signaling. The potential for regulation of human Mfn2 gene expression in vivo is largely unknown. Based on the presence of mitochondrial dysfunction in insulin-resistant conditions, we have examined whether Mfn2 expression is dysregulated in skeletal muscle from obese or nonobese type 2 diabetic subjects, whether muscle Mfn2 expression is regulated by body weight loss, and the potential regulatory role of tumor necrosis factor (TNF)α or interleukin-6. We show that mRNA concentration of Mfn2 is decreased in skeletal muscle from both male and female obese subjects. Muscle Mfn2 expression was also reduced in lean or in obese type 2 diabetic patients. There was a strong negative correlation between the Mfn2 expression and the BMI in nondiabetic and type 2 diabetic subjects. A positive correlation between the Mfn2 expression and the insulin sensitivity was also detected in nondiabetic and type 2 diabetic subjects. To determine the effect of weight loss on Mfn2 mRNA expression, six morbidly obese subjects were subjected to weight loss by bilio-pancreatic diversion. Mean expression of muscle Mfn2 mRNA increased threefold after reduction in body weight, and a positive correlation between muscle Mfn2 expression and insulin sensitivity was again detected. In vitro experiments revealed an inhibitory effect of TNFα or interleukin-6 on Mfn2 expression in cultured cells. We conclude that body weight loss upregulates the expression of Mfn2 mRNA in skeletal muscle of obese humans, type 2 diabetes downregulates the expression of Mfn2 mRNA in skeletal muscle, Mfn2 expression in skeletal muscle is directly proportional to insulin sensitivity and is inversely proportional to the BMI, TNFα and interleukin-6 downregulate Mfn2 expression and may participate in the dysregulation of Mfn2 expression in obesity or type 2 diabetes, and the in vivo modulation of Mfn2 mRNA levels is an additional level of regulation for the control of muscle metabolism and could provide a molecular mechanism for alterations in mitochondrial function in obesity or type 2 diabetes.
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| 38. |
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| 39. |
- Buenestado, Juan Francisco, et al.
(författare)
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Planetary exploration: Mars on the scope
- 2015
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Ingår i: Journal of Astrobiology and Outreach. - : OMICS Publishing Group. - 2332-2519. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- This article summarizes a practical case of introduction to research and planetary exploration through the analysis of data from the Rover Environmental Monitoring Station (REMS), one of the ten scientific instruments on board the Curiosity rover of the Mars Science Laboratory (MSL), currently operating at the impact crater Gale, on Mars. It is the main aim of this work to show how the data that are publicly available at the Planetary Data System (PDS) can be used to introduce undergraduate students and the general public into the subject of surface exploration and the environment of Mars. In particular, the goal of this practice was to investigate and quantify the heat flux between the rover spacecraft and the Martian surface, the role of the atmosphere in this interaction, and its dependence with seasons, as well as to estimate the thermal contamination of the Martian ground produced by the rover. The ground temperature sensor (GTS) of the REMS instrument has measured in-situ, for the first time ever, the diurnal and seasonal variation of the temperature of the surface on Mars along the rover traverse. This novel study shows that the rover radiative heat flux varies between 10 and 22 W/m2 during the Martian year, which is more than 10% of the solar daily averaged insolation at the top of the atmosphere. In addition, it is shown that the radiative heat flux from the rover to the ground varies with the atmospheric dust load, being the mean annual amplitude of the diurnal variation of the surface temperature of 76 K, as a result of solar heating during the day and infrared cooling during the night. As a remarkable and unexpected outcome, it has been established that the thermal contamination produced by the rover alone induces, on average, a systematic shift of 7.5 K, which is indeed about 10% of the one produced by solar heating. This result may have implications for the design and operation of future surface exploration probes such as InSight.
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| 40. |
- Cockell, C.S., et al.
(författare)
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Habitability : a review
- 2016
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Ingår i: Astrobiology. - : Mary Ann Liebert Inc. - 1531-1074 .- 1557-8070. ; 16:1, s. 89-117
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Tidskriftsartikel (refereegranskat)abstract
- Habitability is a widely used word in the geoscience, planetary science, and astrobiology literature, but what does it mean? In this review on habitability, we define it as the ability of an environment to support the activity of at least one known organism. We adopt a binary definition of “habitability” and a “habitable environment.” An environment either can or cannot sustain a given organism. However, environments such as entire planets might be capable of supporting more or less species diversity or biomass compared with that of Earth. A clarity in understanding habitability can be obtained by defining instantaneous habitability as the conditions at any given time in a given environment required to sustain the activity of at least one known organism, and continuous planetary habitability as the capacity of a planetary body to sustain habitable conditions on some areas of its surface or within its interior over geological timescales. We also distinguish between surface liquid water worlds (such as Earth) that can sustain liquid water on their surfaces and interior liquid water worlds, such as icy moons and terrestrial-type rocky planets with liquid water only in their interiors. This distinction is important since, while the former can potentially sustain habitable conditions for oxygenic photosynthesis that leads to the rise of atmospheric oxygen and potentially complex multicellularity and intelligence over geological timescales, the latter are unlikely to. Habitable environments do not need to contain life. Although the decoupling of habitability and the presence of life may be rare on Earth, it may be important for understanding the habitability of other planetary bodies
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| 41. |
- G. Trainer, Melissa, et al.
(författare)
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Seasonal Variations in Atmospheric Composition as Measured in Gale Crater, Mars
- 2019
-
Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 124:11, s. 3000-3024
-
Tidskriftsartikel (refereegranskat)abstract
- The Sample Analysis at Mars (SAM) instrument onboard the Mars Science Laboratory Curiosity rover measures the chemical composition of major atmospheric species (CO2, N2, 40Ar, O2, and CO) through a dedicated atmospheric inlet. We report here measurements of volume mixing ratios in Gale Crater using the SAM quadrupole mass spectrometer, obtained over a period of nearly 5 years (3 Mars years) from landing. The observation period spans the northern summer of MY 31 and solar longitude (LS) of 175° through spring of MY 34, LS = 12°. This work expands upon prior reports of the mixing ratios measured by SAM QMS in the first 105 sols of the mission. The SAM QMS atmospheric measurements were taken periodically, with a cumulative coverage of four or five experiments per season on Mars. Major observations include the seasonal cycle of CO2, N2, and Ar, which lags approximately 20–40° of LS behind the pressure cycle driven by CO2 condensation and sublimation from the winter poles. This seasonal cycle indicates that transport occurs on faster timescales than mixing. The mixing ratio of O2 shows significant seasonal and interannual variability, suggesting an unknown atmospheric or surface process at work. The O2 measurements are compared to several parameters, including dust optical depth and trace CH4 measurements by Curiosity. We derive annual mean volume mixing ratios for the atmosphere in Gale Crater: CO2 = 0.951 (±0.003), N2 = 0.0259 (±0.0006), 40Ar = 0.0194 (±0.0004), O2 = 1.61 (±0.09) x 10‐3, and CO = 5.8 (±0.8) x 10‐4.
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| 42. |
- Gaite, José A., et al.
(författare)
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Nonlinear spherical gravitational downfall of gas onto a solid ball : Analytic and numerical results
- 2003
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Ingår i: Physica D. - : Elsevier. - 0167-2789 .- 1872-8022. ; 183:1-2, s. 102-116
-
Tidskriftsartikel (refereegranskat)abstract
- The process of downfall of initially homogeneous gas onto a solid ball due to the ball's gravity (relevant in astrophysical situations) is studied with a combination of analytic and numerical methods. The initial explicit solution soon becomes discontinuous and gives rise to a shock wave. Afterwards, there is a crossover between two intermediate asymptotic similarity regimes, where the shock wave propagates outwards according to two self-similar laws, initially accelerating and eventually decelerating and vanishing, leading to a static state. The numerical study allows one to investigate in detail this dynamical problem and its time evolution, verifying and complementing the analytic results on the initial solution, intermediate self-similar laws and static long-term solution.
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| 43. |
- Gebhardt, C., et al.
(författare)
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Characterizing Dust‐Radiation Feedback and Refining the Horizontal Resolution of the MarsWRF Model down to 0.5 Degree
- 2021
-
Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 126:3
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, three simulations by the Mars Weather Research and Forecasting (MarsWRF) model are compared: two 10 Martian Year (MY) 2° × 2° simulations with (i) fully radiatively‐active dust and (ii) a prescribed dust scenario, and a (iii) 1 MY 0.5° × 0.5° simulation with prescribed dust as in (ii). From comparing (i) and (ii), we found that the impact of dust‐radiation feedback is individually different for any region. The most striking evidence are major dust lifting activities to the south of Chryse Planitia (S‐CP) seen in (i) but not in (ii). By contrast, dust lifting and deposition on the southern slopes and inside the Hellas Basin are similar in both simulations. The latter, in turn, points towards a similar near‐surface atmospheric circulation. In (iii), the total global amount of wind stress lifted dust is by a factor of ∼8 higher than in (ii), with S‐CP being a major lifting region as in (i). Nonetheless, the surface dust lifting by wind stress in (iii) may be also reduced regionally, as seen at the peak of Elysium Mons because of its unique topography. The zonal mean circulation in (i) is generally of a comparable strength to that in (ii), with exceptions in global dust storm years, when it is clearly stronger in (i), in line with a dustier atmosphere. The differences in the zonal mean circulation between (ii) and (iii) are mostly at lower altitudes, and may arise due to differences in the representation of the topography.
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| 44. |
- Gebhardt, C., et al.
(författare)
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Fully Interactive and Refined Resolution Simulations of the Martian Dust Cycle by the MarsWRF Model
- 2020
-
Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 125:9
-
Tidskriftsartikel (refereegranskat)abstract
- The MarsWRF model is set up with fully interactive dust at 5° × 5° and 2° × 2 resolution. The latter allows for a better representation of topography and other surface properties. An infinite reservoir of surface dust is assumed for both resolutions. For 5° × 5°, surface dust lifting by wind stress takes place over broad areas, occurring in about 20% of the model’s grid cells. For 2° × 2°, it is more spatially restricted, occurring in less than 5% of the grid cells, and somewhat reminiscent of the corridors Acidalia‐Chryse, Utopia‐Isidis, and Arcadia‐West of Tharsis. The onset times of major dust storms ‐ large regional storms or global dust storm events (GDEs) ‐ do not exhibit much inter‐annual variability, typically occurring at around Ls 260°. However, their magnitude does show significant inter‐annual variability ‐ with only small regional storms in some years, large regional storms in others, and some years with GDEs ‐ owing to the interaction between major dust lifting regions at low latitudes. The latter is consistent with observed GDEs having several active dust lifting centers. The model’s dust distribution is found to better agree with observation‐based albedo and dust cover index maps for the 2° × 2° run. For the latter, there is also significant surface dust lifting by wind stress in the aphelion season that is largely confined to the Hellas basin. It has a recurring time pattern of 2‐7 sols, possibly resulting from the interaction between mid‐latitude baroclinic systems and local downslope flows.
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| 45. |
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| 46. |
- Guzewich, Scott D., et al.
(författare)
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The Vertical Dust Profile over Gale Crater, Mars
- 2017
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Ingår i: Journal of Geophysical Research - Planets. - : American Geophysical Union (AGU). - 2169-9097 .- 2169-9100. ; 122:12, s. 2779-2792
-
Tidskriftsartikel (refereegranskat)abstract
- We create a vertically coarse, but complete, vertical profile of dust mixing ratio from the surface to the upper atmosphere over Gale Crater, Mars, using the frequent joint atmospheric observations of the orbiting Mars Climate Sounder (MCS) and the Mars Science Laboratory (MSL) Curiosity rover. Using these data and an estimate of planetary boundary layer (PBL) depth from the MarsWRF general circulation model, we divide the vertical column into three regions. The first region is the Gale Crater PBL, the second is the MCS-sampled region, and the third is between these first two. We solve for a well-mixed dust mixing ratio within this third (middle) layer of atmosphere to complete the profile.We identify a unique seasonal cycle of dust within each atmospheric layer. Within the Gale PBL, dust mixing ratio maximizes near southern hemisphere summer solstice (Ls = 270°) and minimizes near winter solstice (Ls = 90-100°) with a smooth sinusoidal transition between them. However, the layer above Gale Crater and below the MCS-sampled region more closely follows the global opacity cycle and has a maximum in opacity near Ls = 240° and exhibits a local minimum (associated with the “solsticial pause” in dust storm activity) near Ls = 270°. With knowledge of the complete vertical dust profile, we can also assess the frequency of high-altitude dust layers over Gale. We determine that 36% of MCS profiles near Gale Crater contain an “absolute” high-altitude dust layer wherein the dust mixing ratio is the maximum in the entire vertical column.
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| 47. |
- Hamilton, Victoria E., et al.
(författare)
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Observations and preliminary science results from the first 100 sols of MSL Rover Environmental Monitoring Station ground temperature sensor measurements at Gale Crater
- 2014
-
Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 119:4, s. 745-770
-
Tidskriftsartikel (refereegranskat)abstract
- We describe preliminary results from the first 100 sols of ground temperature measurements along the Mars Science Laboratory's traverse from Bradbury Landing to Rocknest in Gale. The ground temperature data show long-term increases in mean temperature that are consistent with seasonal evolution. Deviations from expected temperature trends within the diurnal cycle are observed and may be attributed to rover and environmental effects. Fits to measured diurnal temperature amplitudes using a thermal model suggest that the observed surfaces have thermal inertias in the range of 265-375?J m-2 K-1 s-1/2, which are within the range of values determined from orbital measurements and are consistent with the inertias predicted from the observed particle sizes on the uppermost surface near the rover. Ground temperatures at Gale Crater appear to warm earlier and cool later than predicted by the model, suggesting that there are multiple unaccounted for physical conditions or processes in our models. Where the Mars Science Laboratory (MSL) descent engines removed a mobile layer of dust and fine sediments from over rockier material, the diurnal temperature profile is closer to that expected for a homogeneous surface, suggesting that the mobile materials on the uppermost surface may be partially responsible for the mismatch between observed temperatures and those predicted for materials having a single thermal inertia. Models of local stratigraphy also implicate thermophysical heterogeneity at the uppermost surface as a potential contributor to the observed diurnal temperature cycle. Key Points Diurnal ground temperatures vary with location Diurnal temperature curves are not well matched by a homogeneous thermal model GTS data are consistent with a varied stratigraphy and thermophysical properties.
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| 48. |
- Moore, Casey A., et al.
(författare)
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A Full Martian Year of Line-of-Sight Extinction within Gale Crater, Mars as Acquired by the MSL Navcam through sol 900
- 2016
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Ingår i: Icarus. - : Elsevier BV. - 0019-1035 .- 1090-2643. ; 264, s. 102-108
-
Tidskriftsartikel (refereegranskat)abstract
- We report on line-of-sight extinction in northern Gale Crater, Mars as seen by the Mars Science Laboratory (MSL) rover, Curiosity from sol 100 to sol 900; a little more than an entire martian year. Navcam images oriented due north, which show the distant crater rim, the near ground and the sky allow the extinction due to dust within the crater to be determined. This line-of sight extinction is compared to a complementary dataset of column extinctions derived from Mastcam. The line-of-sight extinction within the crater is less than the column extinction for the majority of the martian year. This implies that the relatively low mixing ratio of dust within the crater as compared to the atmosphere above the crater rim persists through most of the year. This suggests relatively little mixing between the atmosphere above the crater and the atmosphere inside the crater and suggests that northern Gale Crater is a net sink of dust in the current era. The data does however show a yearly convergence of the line-of-sight extinction and the column-averaged extinction around Ls = 270° – 290°. This suggests that air above the crater mixes with air in the crater at this time, as predicted by mesoscale models. Matching line-of-sight and column extinction values are also seen around Ls ≈ 135°, a season that has only been observed once in this dataset, this is particularly interesting as the Rover Environmental Monitoring Station onboard Curiosity reports increased convective boundary layer heights in the same season.
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| 49. |
- Moores, John E., et al.
(författare)
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Atmospheric movies acquired at the Mars Science Laboratory landing site : Cloud Morphology, Frequency and Significance to the Gale Crater Water Cycle and Phoenix Mission Results
- 2015
-
Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 55:9, s. 2217-2238
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first 360 sols (LS 150° to 5°), representing just over half a Martian year, of atmospheric monitoring movies acquired using the NavCam imager from the Mars Science Laboratory (MSL) Rover Curiosity. Such movies reveal faint clouds that are difficult to discern in single images. The data set acquired was divided into two different classifications depending upon the orientation and intent of the observation. Up to sol 360, 73 Zenith Movies and 79 Supra-Horizon Movies have been acquired and time-variable features could be discerned in 25 of each. The data set from MSL is compared to similar observations made by the Surface Stereo Imager (SSI) onboard the Phoenix Lander and suggests a much drier environment at Gale Crater (4.6°S) during this season than was observed in Green Valley (68.2°N) as would be expected based on latitude and the global water cycle. The optical depth of the variable component of clouds seen in images with features are up to 0.047 ± 0.009 with a granularity to the features observed which averages 3.8 degrees. MCS also observes clouds during the same period of comparable optical depth at 30 and 50 km that would suggest a cloud spacing of 2.0 to 3.3 km. Multiple motions visible in atmospheric movies support the presence of two distinct layers of clouds. At Gale Crater, these clouds are likely caused by atmospheric waves given the regular spacing of features observed in many Zenith movies and decreased spacing towards the horizon in sunset movies consistent with clouds forming at a constant elevation. Reanalysis of Phoenix data in the light of the NavCam equatorial dataset suggests that clouds may have been more frequent in the earlier portion of the Phoenix mission than was previously thought.
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| 50. |
- Navarro‐González, Rafael, et al.
(författare)
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Abiotic Input of Fixed Nitrogen by Bolide Impacts to Gale Crater During the Hesperian : Insights From the Mars Science Laboratory
- 2019
-
Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 124:1, s. 94-113
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Tidskriftsartikel (refereegranskat)abstract
- Molecular hydrogen (H2) from volcanic emissions is suggested to warm the Martian surface when carbon dioxide (CO2) levels dropped from the Noachian (4100 to 3700 Myr) to the Hesperian (3700 to 3000 Myr). Its presence is expected to shift the conversion of molecular nitrogen (N2) into different forms of fixed nitrogen (N). Here we present experimental data and theoretical calculations that investigate the efficiency of nitrogen fixation by bolide impacts in CO2‐N2 atmospheres with or without H2. Surprisingly, nitric oxide (NO) was produced more efficiently in 20% H2 in spite of being a reducing agent and not likely to increase the rate of nitrogen oxidation. Nevertheless, its presence led to a faster cooling of the shock wave raising the freeze‐out temperature of NO resulting in an enhanced yield. We estimate that the nitrogen fixation rate by bolide impacts varied from 7 × 10−4 to 2 × 10−3 g N·Myr−1·cm−2 and could imply fluvial concentration to explain the nitrogen (1.4 ± 0.7 g N·Myr−1·cm−2) detected as nitrite (NO2−) and nitrate (NO3−) by Curiosity at Yellowknife Bay. One possible explanation is that the nitrogen detected in the lacustrine sediments at Gale was deposited entirely on the crater's surface and was subsequently dissolved and transported by superficial and ground waters to the lake during favorable wet climatic conditions. The nitrogen content sharply decreases in younger sediments of the Murray formation suggesting a decline of H2 in the atmosphere and the rise of oxidizing conditions causing a shortage in the supply to putative microbial life.
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