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Sample records for survive martian conditions

  1. Effect of Shadowing on Survival of Bacteria under Conditions Simulating the Martian Atmosphere and UV Radiation▿ †

    Science.gov (United States)

    Osman, Shariff; Peeters, Zan; La Duc, Myron T.; Mancinelli, Rocco; Ehrenfreund, Pascale; Venkateswaran, Kasthuri

    2008-01-01

    Spacecraft-associated spores and four non-spore-forming bacterial isolates were prepared in Atacama Desert soil suspensions and tested both in solution and in a desiccated state to elucidate the shadowing effect of soil particulates on bacterial survival under simulated Martian atmospheric and UV irradiation conditions. All non-spore-forming cells that were prepared in nutrient-depleted, 0.2-μm-filtered desert soil (DSE) microcosms and desiccated for 75 days on aluminum died, whereas cells prepared similarly in 60-μm-filtered desert soil (DS) microcosms survived such conditions. Among the bacterial cells tested, Microbacterium schleiferi and Arthrobacter sp. exhibited elevated resistance to 254-nm UV irradiation (low-pressure Hg lamp), and their survival indices were comparable to those of DS- and DSE-associated Bacillus pumilus spores. Desiccated DSE-associated spores survived exposure to full Martian UV irradiation (200 to 400 nm) for 5 min and were only slightly affected by Martian atmospheric conditions in the absence of UV irradiation. Although prolonged UV irradiation (5 min to 12 h) killed substantial portions of the spores in DSE microcosms (∼5- to 6-log reduction with Martian UV irradiation), dramatic survival of spores was apparent in DS-spore microcosms. The survival of soil-associated wild-type spores under Martian conditions could have repercussions for forward contamination of extraterrestrial environments, especially Mars. PMID:18083857

  2. Survival of Deinococcus geothermalis in Biofilms under Desiccation and Simulated Space and Martian Conditions

    Science.gov (United States)

    Frösler, Jan; Panitz, Corinna; Wingender, Jost; Flemming, Hans-Curt; Rettberg, Petra

    2017-05-01

    Biofilm formation represents a successful survival strategy for bacteria. In biofilms, cells are embedded in a matrix of extracellular polymeric substances (EPS). As they are often more stress-tolerant than single cells, biofilm cells might survive the conditions present in space and on Mars. To investigate this topic, the bacterium Deinococcus geothermalis was chosen as a model organism due to its tolerance toward desiccation and radiation. Biofilms cultivated on membranes and, for comparison, planktonically grown cells deposited on membranes were air-dried and exposed to individual stressors that included prolonged desiccation, extreme temperatures, vacuum, simulated martian atmosphere, and UV irradiation, and they were exposed to combinations of stressors that simulate space (desiccation + vacuum + UV) or martian (desiccation + Mars atmosphere + UV) conditions. The effect of sulfatic Mars regolith simulant on cell viability during stress was investigated separately. The EPS produced by the biofilm cells contained mainly polysaccharides and proteins. To detect viable but nonculturable (VBNC) cells, cultivation-independent viability indicators (membrane integrity, ATP, 16S rRNA) were determined in addition to colony counts. Desiccation for 2 months resulted in a decrease of culturability with minor changes of membrane integrity in biofilm cells and major loss of membrane integrity in planktonic bacteria. Temperatures between -25°C and +60°C, vacuum, and Mars atmosphere affected neither culturability nor membrane integrity in both phenotypes. Monochromatic (254 nm; ≥1 kJ m-2) and polychromatic (200-400 nm; >5.5 MJ m-2 for planktonic cells and >270 MJ m-2 for biofilms) UV irradiation significantly reduced the culturability of D. geothermalis but did not affect cultivation-independent viability markers, indicating the induction of a VBNC state in UV-irradiated cells. In conclusion, a substantial proportion of the D. geothermalis population remained viable under

  3. Survival of Antarctic Cryptoendolithic Fungi in Simulated Martian Conditions On Board the International Space Station.

    Science.gov (United States)

    Onofri, Silvano; de Vera, Jean-Pierre; Zucconi, Laura; Selbmann, Laura; Scalzi, Giuliano; Venkateswaran, Kasthuri J; Rabbow, Elke; de la Torre, Rosa; Horneck, Gerda

    2015-12-01

    Dehydrated Antarctic cryptoendolithic communities and colonies of the rock inhabitant black fungi Cryomyces antarcticus (CCFEE 515) and Cryomyces minteri (CCFEE 5187) were exposed as part of the Lichens and Fungi Experiment (LIFE) for 18 months in the European Space Agency's EXPOSE-E facility to simulated martian conditions aboard the International Space Station (ISS). Upon sample retrieval, survival was proved by testing colony-forming ability, and viability of cells (as integrity of cell membrane) was determined by the propidium monoazide (PMA) assay coupled with quantitative PCR tests. Although less than 10% of the samples exposed to simulated martian conditions were able to proliferate and form colonies, the PMA assay indicated that more than 60% of the cells and rock communities had remained intact after the "Mars exposure." Furthermore, a high stability of the DNA in the cells was demonstrated. The results contribute to assessing the stability of resistant microorganisms and biosignatures on the surface of Mars, data that are valuable information for further search-for-life experiments on Mars. Endoliths-Eukaryotes-Extremophilic microorganisms-Mars-Radiation resistance.

  4. Biotoxicity of Mars soils: 1. Dry deposition of analog soils on microbial colonies and survival under Martian conditions

    Science.gov (United States)

    Schuerger, Andrew C.; Golden, D. C.; Ming, Doug W.

    2012-11-01

    Six Mars analog soils were created to simulate a range of potentially biotoxic geochemistries relevant to the survival of terrestrial microorganisms on Mars, and included basalt-only (non-toxic control), salt, acidic, alkaline, aeolian, and perchlorate rich geochemistries. Experiments were designed to simulate the dry-deposition of Mars soils onto spacecraft surfaces during an active descent landing scenario with propellant engines. Six eubacteria were initially tested for tolerance to desiccation, and the spore-former Bacillus subtilis HA101 and non-spore former Enterococcus faecalis ATCC 29212 were identified to be strongly resistant (HA101) and moderately resistant (29212) to desiccation at 24 °C. Furthermore, tests with B. subtilis and E. faecalis demonstrated that at least 1 mm of Mars analog soil was required to fully attenuate the biocidal effects of a simulated Mars-normal equatorial UV flux. Biotoxicity experiments were conducted under simulated Martian conditions of 6.9 mbar, -10 °C, CO2-enriched anoxic atmosphere, and a simulated equatorial solar spectrum (200-1100 nm) with an optical depth of 0.1. For B. subtilis, the six analog soils were found, in general, to be of low biotoxicity with only the high salt and acidic soils exhibiting the capacity to inactivate a moderate number of spores (<1 log reductions) exposed 7 days to the soils under simulated Martian conditions. In contrast, the overall response of E. faecalis to the analog soils was more dramatic with between two and three orders of magnitude reductions in viable cells for most soils, and between six and seven orders of magnitude reductions observed for the high-salt soil. Results suggest that Mars soils are likely not to be overtly biotoxic to terrestrial microorganisms, and suggest that the soil geochemistries on Mars will not preclude the habitability of the Martian surface.

  5. Extended Survival of Several Microorganisms and Relevant Amino Acid Biomarkers under Simulated Martian Surface Conditions as a Function of Burial Depth

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Adam [Indiana University; Pratt, L.M. [Indiana University; Vishnivetskaya, Tatiana A [ORNL; Pfiffner, S. M. [University of Tennessee, Knoxville (UTK); Bryan, R. A. [Yeshiva University, New York; Dadachova, E. [Yeshiva University, New York; Whyte, L G [McGill University, Montreal, Quebec; Radtke, K. [McGill University, Montreal, Quebec; Chan, E. [Princeton University; Tronick, S. [Princeton University; Borgonie, G. [Ghent University, Belgium; Mancinelli, R. [SETI Institute; Rothschild, L. [NASA Ames Research Center; Rogoff, D. [NASA Ames Research Center; Horikawa, D. D. [NASA Ames Research Center; Onstott, T. C. [Princeton University

    2011-01-01

    Recent orbital and landed missions have provided substantial evidence for ancient liquid water on the martian surface as well as evidence of more recent sedimentary deposits formed by water and/or ice. These observations raise serious questions regarding an independent origin and evolution of life on Mars. Future missions seek to identify signs of extinct martian biota in the form of biomarkers or morphological characteristics, but the inherent danger of spacecraft-borne terrestrial life makes the possibility of forward contamination a serious threat not only to the life detection experiments, but also to any extant martian ecosystem. A variety of cold and desiccation-tolerant organisms were exposed to 40 days of simulated martian surface conditions while embedded within several centimeters of regolith simulant in order to ascertain the plausibility of such organisms survival as a function of environmental parameters and burial depth. Relevant amino acid biomarkers associated with terrestrial life were also analyzed in order to understand the feasibility of detecting chemical evidence for previous biological activity. Results indicate that stresses due to desiccation and oxidation were the primary deterrent to organism survival, and that the effects of UV-associated damage, diurnal temperature variations, and reactive atmospheric species were minimal. Organisms with resistance to desiccation and radiation environments showed increased levels of survival after the experiment compared to organisms characterized as psychrotolerant. Amino acid analysis indicated the presence of an oxidation mechanism that migrated downward through the samples during the course of the experiment and likely represents the formation of various oxidizing species at mineral surfaces as water vapor diffused through the regolith. Current sterilization protocols may specifically select for organisms best adapted to survival at the martian surface, namely species that show tolerance to radical

  6. Survival of Moss Reproductive Structures under Simulated Martian Environmental Conditions and Extreme Thermal Stress: Vibrational Spectroscopic Study and Astrobiological Implications

    OpenAIRE

    Gómez Gómez, José María; Estébanez, Belén; Sanz-Arranz, Aurelio; Mateo-Martí, Eva; Medina, Jesús; Rull, Fernando

    2016-01-01

    The principal goal of astrobiology is the search for extraterrestrial life forms. A key aspect is the study of the ability of different kinds of terrestrial organisms to support simulated extraterrestrial environmental conditions. Mosses are multicellular green plants, poorly studied from an astrobiological perspective. In this paper, we report experimental results obtained using two species of moss, which demonstrate that both the spores of the moss Funaria hygrometrica as well a...

  7. Microbial Survival Rates of Escherichia coli and Deinococcus radiodurans Under Low Temperature, Low Pressure, and UV-Irradiation Conditions, and Their Relevance to Possible Martian Life

    Science.gov (United States)

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35°C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m2). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  8. Microbial survival rates of Escherichia coli and Deinococcus radiodurans under low temperature, low pressure, and UV-Irradiation conditions, and their relevance to possible Martian life.

    Science.gov (United States)

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35 degrees C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m(2)). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  9. Water retention of selected microorganisms and Martian soil simulants under close to Martian environmental conditions

    Science.gov (United States)

    Jänchen, J.; Bauermeister, A.; Feyh, N.; de Vera, J.-P.; Rettberg, P.; Flemming, H.-C.; Szewzyk, U.

    2014-08-01

    Based on the latest knowledge about microorganisms resistant towards extreme conditions on Earth and results of new complex models on the development of the Martian atmosphere we quantitatively examined the water-bearing properties of selected extremophiles and simulated Martian regolith components and their interaction with water vapor under close to Martian environmental conditions. Three different species of microorganisms have been chosen and prepared for our study: Deinococcus geothermalis, Leptothrix sp. OT_B_406, and Xanthoria elegans. Further, two mineral mixtures representing the early and the late Martian surface as well as montmorillonite as a single component of phyllosilicatic minerals, typical for the Noachian period on Mars, were selected. The thermal mass loss of the minerals and bacteria-samples was measured by thermoanalysis. The hydration and dehydration properties were determined under close to Martian environmental conditions by sorption isotherm measurements using a McBain-Bakr quartz spring balance. It was possible to determine the total water content of the materials as well as the reversibly bound water fraction as function of the atmospheres humidity by means of these methods. Our results are important for the evaluation of future space mission outcomes including astrobiological aspects and can support the modeling of the atmosphere/surface interaction by showing the influence on the water inventory of the upper most layer of the Martian surface.

  10. Desert Cyanobacteria under simulated space and Martian conditions

    Science.gov (United States)

    Billi, D.; Ghelardini, P.; Onofri, S.; Cockell, C. S.; Rabbow, E.; Horneck, G.

    2008-09-01

    The environment in space and on planets such as Mars, can be lethal to living organisms and high levels of tolerance to desiccation, cold and radiation are needed for survival: rock-inhabiting cyanobacteria belonging to the genus Chroococcidiopsis can fulfil these requirements [1]. These cyanobacteria constantly appear in the most extreme and dry habitats on Earth, including the McMurdo Dry Valleys (Antarctica) and the Atacama Desert (Chile), which are considered the closest terrestrial analogs of two Mars environmental extremes: cold and aridity. In their natural environment, these cyanobacteria occupy the last refuges for life inside porous rocks or at the stone-soil interfaces, where they survive in a dry, dormant state for prolonged periods. How desert strains of Chroococcidiopsis can dry without dying is only partially understood, even though experimental evidences support the existence of an interplay between mechanisms to avoid (or limit) DNA damage and repair it: i) desert strains of Chroococcidiopsis mend genome fragmentation induced by ionizing radiation [2]; ii) desiccation-survivors protect their genome from complete fragmentation; iii) in the dry state they show a survival to an unattenuated Martian UV flux greater than that of Bacillus subtilis spores [3], and even though they die following atmospheric entry after having orbited the Earth for 16 days [4], they survive to simulated shock pressures up to 10 GPa [5]. Recently additional experiments were carried out at the German Aerospace Center (DLR) of Cologne (Germany) in order to identify suitable biomarkers to investigate the survival of Chroococcidiopsis cells present in lichen-dominated communities, in view of their direct and long term space exposition on the International Space Station (ISS) in the framework of the LIchens and Fungi Experiments (LIFE, EXPOSEEuTEF, ESA). Multilayers of dried cells of strains CCMEE 134 (Beacon Valley, Antarctica), and CCMEE 123 (costal desert, Chile ), shielded by

  11. Filter Media Tests Under Simulated Martian Atmospheric Conditions

    Science.gov (United States)

    Agui, Juan H.

    2016-01-01

    Human exploration of Mars will require the optimal utilization of planetary resources. One of its abundant resources is the Martian atmosphere that can be harvested through filtration and chemical processes that purify and separate it into its gaseous and elemental constituents. Effective filtration needs to be part of the suite of resource utilization technologies. A unique testing platform is being used which provides the relevant operational and instrumental capabilities to test articles under the proper simulated Martian conditions. A series of tests were conducted to assess the performance of filter media. Light sheet imaging of the particle flow provided a means of detecting and quantifying particle concentrations to determine capturing efficiencies. The media's efficiency was also evaluated by gravimetric means through a by-layer filter media configuration. These tests will help to establish techniques and methods for measuring capturing efficiency and arrestance of conventional fibrous filter media. This paper will describe initial test results on different filter media.

  12. Photosynthetic Activity and Adaptation Capacities of Lichens and Cyanobacteria to Martian Surface Conditions

    Science.gov (United States)

    De Vera, Jean-Pierre; Schulze-Makuch, D.; Khan, A.; Lorek, A.; Koncz, A.; Stivaletta, N.; Möhlmann, D.; Spohn, T.

    2012-05-01

    We observed an increase in photosynthetic activity in the lichen Pleopsidium chlorophanum but a strong negative effect on the photosynthetic activity of endolithic cyanobacteria when subjected for 34 days to environmental stresses likely to be encountered in semi-protected habitats on the Martian surface. Stresses were simulated in a Mars Simulation Chamber (MSC) and included high UV fluxes, low temperatures, low water activity, high atmospheric CO2 concentrations, and an atmospheric pressure of about 6 mbar. P. chlorophanum is an extremophile: it lives in very cold, dry, high-altitude habitats which are Earth's best approximation of the Martian surface. Our lichen samples came from North Victoria Land in Antarctica whereas the investigated samples of cyanobacteria came from tropic regions in the Sahara. Three samples of each group of organisms were exposed uninterruptedly to simulated conditions (as above) of the naked, unprotected Martian surface for 34 days, receiving the full Martian solar spectrum (200 - 2500 nm) for a cumulative UV dose of 6343.6 kJm-2. For a second sample set - containing also three lichen thalli and three endolithic cyanobacteria communities - the cumulative (34-day) UV dose was reduced to 268.8 kJm-2, to reasonably simulate the amount the microorganisms might receive in (semi-) protected surface sites (e.g., fissures, cracks and micro-caves within rocks or permafrost soil). In the 'unprotected' experiment it was unclear if the lichen was still actively photosynthesizing but still clear that the cyanobacteria were affected. However, under 'protected site' conditions, the cyanobacteria had no clear photosynthetic response under and after simulated Martian conditions but the lichen not only survived and remained photosynthetically active, it even adapted physiologically by increasing its photosynthetic activity over 34 days. Comparison with other Mars simulation experiments on exposure platforms in space and in the laboratory with other

  13. "Deinococcus radiodurans" - a model organism for life under Martian conditions

    Science.gov (United States)

    Rettberg, P.; de La Vega, U.; Horneck, G.

    2004-03-01

    Deinococcus radiodurans, a gram positive bacterium whose ability to survive extremely high damage to its DNA which is for example induced by genotoxic chemicals, ionizing radiation, UV radiation or desiccation is still not completely understood. Because of its radiation and desiccation resistance, this extremophile is a prime candidate for possibly surviving environmental conditions as they occur on Mars and during a hypothetical interplanetary space travel. So far just minor work has been done on the damaging effects of UV radiation, especially polychromatic UV radiation in the UVB and UVA range, and desiccation/vacuum exposure, which is known to induce DNA damages similar to radiation. Therefore, we started to further investigate the radiation resistance and the repair mechanisms of Deinococcus radiodurans, concentrating on the effect of polychromatic UV radiation and desiccation in the wild type strain and ionizing radiation and UV radiation sensitive mutants. The results of this ongoing project will be of great interest to questions concerning planetary protection, spacecraft disinfecting measures and the search for life on other earth-like planets in general.

  14. Damage escape and repair in dried Chroococcidiopsis spp. from hot and cold deserts exposed to simulated space and martian conditions.

    Science.gov (United States)

    Billi, Daniela; Viaggiu, Emanuela; Cockell, Charles S; Rabbow, Elke; Horneck, Gerda; Onofri, Silvano

    2011-01-01

    The cyanobacterium Chroococcidiopsis, overlain by 3 mm of Antarctic sandstone, was exposed as dried multilayers to simulated space and martian conditions. Ground-based experiments were conducted in the context of Lichens and Fungi Experiments (EXPOSE-E mission, European Space Agency), which were performed to evaluate, after 1.5 years on the International Space Station, the survival of cyanobacteria (Chroococcidiopsis), lichens, and fungi colonized on Antarctic rock. The survival potential and the role played by protection and repair mechanisms in the response of dried Chroococcidiopsis cells to ground-based experiments were both investigated. Different methods were employed, including evaluation of the colony-forming ability, single-cell analysis of subcellular integrities based on membrane integrity molecular and redox probes, evaluation of the photosynthetic pigment autofluorescence, and assessment of the genomic DNA integrity with a PCR-based assay. Desiccation survivors of strain CCMEE 123 (coastal desert, Chile) were better suited than CCMEE 134 (Beacon Valley, Antarctica) to withstand cellular damage imposed by simulated space and martian conditions. Exposed dried cells of strain CCMEE 123 formed colonies, maintained subcellular integrities, and, depending on the exposure conditions, also escaped DNA damage or repaired the induced damage upon rewetting.

  15. Magnesium Sulfate Salt Solutions and Ices Fail to Protect Serratia liquefaciens from the Biocidal Effects of UV Irradiation under Martian Conditions

    Science.gov (United States)

    Mickol, Rebecca L.; Page, Jessica L.; Schuerger, Andrew C.

    2017-05-01

    The growth of Serratia liquefaciens has been demonstrated under martian conditions of 0.7 kPa (7 mbar), 0°C, and CO2-enriched anoxic atmospheres (Schuerger et al., 2013, Astrobiology 13:115-131), but studies into the survivability of cells under hypersaline conditions that are likely to be encountered on Mars are lacking. Serratia liquefaciens cells were suspended in aqueous MgSO4 solutions, or frozen brines, and exposed to terrestrial (i.e., 101.3 kPa, 24°C, O2/N2-normal atmosphere) or martian (i.e., 0.7 kPa, -25°C, CO2-anoxic atmosphere) conditions to assess the roles of MgSO4 and UV irradiation on the survival of S. liquefaciens. Four solutions were tested for their capability to attenuate martian UV irradiation in both liquid and frozen forms: sterile deionized water (SDIW), 10 mM PO4 buffer, 5% MgSO4, and 10% MgSO4. None of the solutions in either liquid or frozen forms provided enhanced protection against martian UV irradiation. Sixty minutes of UV irradiation reduced cell densities from 2.0 × 106 cells/mL to less than 10 cells/mL for both liquid and frozen solutions. In contrast, 3-4 mm of a Mars analog soil were sufficient to attenuate 100% of UV irradiation. Results suggest that terrestrial microorganisms may not survive on Sun-exposed surfaces on Mars, even if the cells are embedded in frozen martian brines composed of MgSO4. However, if dispersed microorganisms can be covered by only a few millimeters of dust or regolith, long-term survival is probable.

  16. Thermal conductivity measurements of particulate materials under Martian conditions

    Science.gov (United States)

    Presley, M. A.; Christensen, P. R.

    1993-01-01

    The mean particle diameter of surficial units on Mars has been approximated by applying thermal inertia determinations from the Mariner 9 Infrared Radiometer and the Viking Infrared Thermal Mapper data together with thermal conductivity measurement. Several studies have used this approximation to characterize surficial units and infer their nature and possible origin. Such interpretations are possible because previous measurements of the thermal conductivity of particulate materials have shown that particle size significantly affects thermal conductivity under martian atmospheric pressures. The transfer of thermal energy due to collisions of gas molecules is the predominant mechanism of thermal conductivity in porous systems for gas pressures above about 0.01 torr. At martian atmospheric pressures the mean free path of the gas molecules becomes greater than the effective distance over which conduction takes place between the particles. Gas particles are then more likely to collide with the solid particles than they are with each other. The average heat transfer distance between particles, which is related to particle size, shape and packing, thus determines how fast heat will flow through a particulate material.The derived one-to-one correspondence of thermal inertia to mean particle diameter implies a certain homogeneity in the materials analyzed. Yet the samples used were often characterized by fairly wide ranges of particle sizes with little information about the possible distribution of sizes within those ranges. Interpretation of thermal inertia data is further limited by the lack of data on other effects on the interparticle spacing relative to particle size, such as particle shape, bimodal or polymodal mixtures of grain sizes and formation of salt cements between grains. To address these limitations and to provide a more comprehensive set of thermal conductivities vs. particle size a linear heat source apparatus, similar to that of Cremers, was assembled to

  17. Kombucha Multimicrobial Community under Simulated Spaceflight and Martian Conditions

    Science.gov (United States)

    Podolich, O.; Zaets, I.; Kukharenko, O.; Orlovska, I.; Reva, O.; Khirunenko, L.; Sosnin, M.; Haidak, A.; Shpylova, S.; Rabbow, E.; Skoryk, M.; Kremenskoy, M.; Demets, R.; Kozyrovska, N.; de Vera, J.-P.

    2017-05-01

    Kombucha microbial community (KMC) produces a cellulose-based biopolymer of industrial importance and a probiotic beverage. KMC-derived cellulose-based pellicle film is known as a highly adaptive microbial macrocolony—a stratified community of prokaryotes and eukaryotes. In the framework of the multipurpose international astrobiological project "BIOlogy and Mars Experiment (BIOMEX)," which aims to study the vitality of prokaryotic and eukaryotic organisms and the stability of selected biomarkers in low Earth orbit and in a Mars-like environment, a cellulose polymer structural integrity will be assessed as a biomarker and biotechnological nanomaterial. In a preflight assessment program for BIOMEX, the mineralized bacterial cellulose did not exhibit significant changes in the structure under all types of tests. KMC members that inhabit the cellulose-based pellicle exhibited a high survival rate; however, the survival capacity depended on a variety of stressors such as the vacuum of space, a Mars-like atmosphere, UVC radiation, and temperature fluctuations. The critical limiting factor for microbial survival was high-dose UV irradiation. In the tests that simulated a 1-year mission of exposure outside the International Space Station, the core populations of bacteria and yeasts survived and provided protection against UV; however, the microbial density of the populations overall was reduced, which was revealed by implementation of culture-dependent and culture-independent methods. Reduction of microbial richness was also associated with a lower accumulation of chemical elements in the cellulose-based pellicle film, produced by microbiota that survived in the post-test experiments, as compared to untreated cultures that populated the film.

  18. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

    DEFF Research Database (Denmark)

    Bak, Ebbe Norskov; Larsen, Michael G.; Moeller, Ralf

    2017-01-01

    The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors......, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model...... in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward...

  19. Habitability Conditions Constrained by Martian Meteorites: Implications for Microbial Colonization and Mars Sample Return

    Science.gov (United States)

    Shivak, J. N.; Banerjee, N.; Flemming, R. L.

    2013-12-01

    We report the results of a comparative study of the crustal environmental conditions recorded by several Martian meteorites (Nakhla, Los Angeles, and Zagami). Though no samples have yet been returned from Mars, numerous meteorites are known and these provide the only samples of the Martian crust currently available for study. Terrestrial basalts and other mafic igneous rocks are analogous in many ways to much of the Martian crust, as evidenced by the composition of known Martian meteorites and measurements from planetary missions [1]. Microorganisms are known to thrive in the terrestrial geosphere and make use of many different substrates within rock in the subsurface of the Earth [2]. The action of aqueous solutions in the Martian crust has been well established through the study of alteration mineral assemblages present in many Martian meteorites, such as the nakhlites [3]. Aqueous activity in terrestrial chemolithoautotrophic habitats provides numerous energy and nutrient sources for microbes [4], suggesting the potential for habitable endolithic environments in Martian rocks. Fayalite in Nakhla has experienced extensive aqueous alteration to reddish-brown 'iddingsite' material within a pervasive fracture system. Textural imaging shows the replacement of primary olivine with various alteration phases and infiltration of this alteration front into host grains. Geochemical analysis of the alteration material shows the addition of iron and silica and removal of magnesium during alteration. Novel In situ Micro-XRD and Raman Spectroscopy of this material reveals a new assemblage consisting of iron oxides, smectite clays, carbonates, and a minor serpentine component. The alteration mineral assemblage here differs from several that have been previously reported [4] [5], allowing for a reevaluation of the environmental conditions during fluid action. Los Angeles and Zagami show no evidence of aqueous activity, though their primary basaltic mineralogies show many

  20. 100 kGy gamma-affected microbial communities within the ancient Arctic permafrost under simulated Martian conditions.

    Science.gov (United States)

    Cheptsov, Vladimir S; Vorobyova, Elena A; Manucharova, Natalia A; Gorlenko, Mikhail V; Pavlov, Anatoli K; Vdovina, Maria A; Lomasov, Vladimir N; Bulat, Sergey A

    2017-11-01

    This research aimed to investigate the viability and biodiversity of microbial communities within ancient Arctic permafrost after exposure to a gamma-radiation dose of 100 kGy at low temperature (- 50 °C), low pressure (1 Torr) and dehydration conditions. The main objective was to assess the possibility for long-term survival of Earth-bound microorganisms in the subsurface of Martian regolith or inside small space bodies at constant absorption and accumulation of the gamma radiation dose. Investigated microbial communities had shown high resistance to a simulated Martian environment. After irradiation the total count of prokaryotic cells and number of metabolically active bacterial cells remained at the control level, while the number of bacterial CFUs decreased by 2 orders of magnitude, and the number of metabolically active cells of archaea decreased threefold. Besides, the abundance of culturable bacteria after irradiation was kept at a high level: not less than 3.7 × 10 5  cells/g. Potential metabolic activity of irradiated microbial communities in general were higher than in the control sample. A fairly high biodiversity of bacteria was detected in the exposed sample of permafrost, although the microbial community structure underwent significant changes after irradiation. In particular, actinobacteria populations of the genus Arthrobacter, which was not revealed in the control samples, became predominant in bacterial communities following the exposure. The results of the study testify that long-term preservation of microbial life inside Martian permafrost is possible. The data obtained can also be evaluated from the perspective of the potential for discovering viable Earth-bound microorganisms on other objects in the Solar system and inside of small bodies in outer space.

  1. Survival of endospores of Bacillus subtilis on spacecraft surfaces under simulated martian environments: implications for the forward contamination of Mars

    Science.gov (United States)

    Schuerger, Andrew C.; Mancinelli, Rocco L.; Kern, Roger G.; Rothschild, Lynn J.; McKay, Christopher P.

    2003-01-01

    Experiments were conducted in a Mars simulation chamber (MSC) to characterize the survival of endospores of Bacillus subtilis under high UV irradiation and simulated martian conditions. The MSC was used to create Mars surface environments in which pressure (8.5 mb), temperature (-80, -40, -10, or +23 degrees C), gas composition (Earth-normal N2/O2 mix, pure N2, pure CO2, or a Mars gas mix), and UV-VIS-NIR fluence rates (200-1200 nm) were maintained within tight limits. The Mars gas mix was composed of CO2 (95.3%), N2 (2.7%), Ar (1.7%), O2 (0.2%), and water vapor (0.03%). Experiments were conducted to measure the effects of pressure, gas composition, and temperature alone or in combination with Mars-normal UV-VIS-NIR light environments. Endospores of B. subtilis, were deposited on aluminum coupons as monolayers in which the average density applied to coupons was 2.47 x 10(6) bacteria per sample. Populations of B. subtilis placed on aluminum coupons and subjected to an Earth-normal temperature (23 degrees C), pressure (1013 mb), and gas mix (normal N2/O2 ratio) but illuminated with a Mars-normal UV-VIS-NIR spectrum were reduced by over 99.9% after 30 sec exposure to Mars-normal UV fluence rates. However, it required at least 15 min of Mars-normal UV exposure to reduce bacterial populations on aluminum coupons to non-recoverable levels. These results were duplicated when bacteria were exposed to Mars-normal environments of temperature (-10 degrees C), pressure (8.5 mb), gas composition (pure CO2), and UV fluence rates. In other experiments, results indicated that the gas composition of the atmosphere and the temperature of the bacterial monolayers at the time of Mars UV exposure had no effects on the survival of bacterial endospores. But Mars-normal pressures (8.5 mb) were found to reduce survival by approximately 20-35% compared to Earth-normal pressures (1013 mb). The primary implications of these results are (a) that greater than 99.9% of bacterial populations on

  2. Clay catalyzed RNA synthesis under Martian conditions: Application for Mars return samples.

    Science.gov (United States)

    Joshi, Prakash C; Dubey, Krishna; Aldersley, Michael F; Sausville, Meaghen

    2015-06-26

    Catalysis by montmorillonites clay minerals is regarded as a feasible mechanism for the abiotic production and polymerization of key biomolecules on early Earth. We have investigated a montmorillonite-catalyzed reaction of the 5'-phosphorimidazolide of nucleosides as a model to probe prebiotic synthesis of RNA-type oligomers. Here we show that this model is specific for the generation of RNA oligomers despite deoxy-mononucleotides adsorbing equally well onto the montmorillonite catalytic surfaces. Optimum catalytic activity was observed over a range of pH (6-9) and salinity (1 ± 0.2 M NaCl). When the weathering steps of early Earth that generated catalytic montmorillonite were modified to meet Martian soil conditions, the catalytic activity remained intact without altering the surface layer charge. Additionally, the formation of oligomers up to tetramer was detected using as little as 0.1 mg of Na⁺-montmorillonite, suggesting that the catalytic activity of a Martian clay return sample can be investigated with sub-milligram scale samples. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Visible and Near-IR Reflectance Spectra of Mars Analogue Materials Under Arid Conditions for Interpretation of Martian Surface Mineralogy

    Science.gov (United States)

    Morris, R. V.; Graff, T. G.; Achilles, C. N.; Agresti, D. G.; Ming, D. W.; Golden, D. C.

    2011-01-01

    Visible and near-IR (VNIR) spectra from the hyper-spectral imagers MRO-CRISM and Mars Express OMEGA in martian orbit have signatures from Fe-bearing phases (e.g., olivine, pyroxene, and jarosite), H2O/OH-bearing phases (e.g., smectites and other phyllosilicates, sulfates, and high-SiO2 phases), and carbonate [e.g., 1-5]. Mineralogical assignments of martian spectral features are made on the basis of VNIR spectra acquired in the laboratory under appropriate environmental conditions on samples whose mineralogical composition is known. We report here additional results for our ongoing project [6] to acquire VNIR spectra under arid conditions.

  4. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria-A Challenge for Life on Mars.

    Science.gov (United States)

    Bak, Ebbe N; Larsen, Michael G; Moeller, Ralf; Nissen, Silas B; Jensen, Lasse R; Nørnberg, Per; Jensen, Svend J K; Finster, Kai

    2017-01-01

    The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

  5. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

    Science.gov (United States)

    Bak, Ebbe N.; Larsen, Michael G.; Moeller, Ralf; Nissen, Silas B.; Jensen, Lasse R.; Nørnberg, Per; Jensen, Svend J. K.; Finster, Kai

    2017-01-01

    The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats. PMID:28955310

  6. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

    Directory of Open Access Journals (Sweden)

    Ebbe N. Bak

    2017-09-01

    Full Text Available The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

  7. Simulation of the environmental climate conditions on martian surface and its effect on Deinococcus radiodurans

    Science.gov (United States)

    de la Vega, U. Pogoda; Rettberg, P.; Reitz, G.

    The resistance of terrestrial microorganisms under the thermo-physical conditions of Mars (diurnal temperature variations, UV climate, atmospheric pressure and gas composition) at mid-latitudes was studied for the understanding and assessment of potential life processes on Mars. In order to accomplish a targeted search for life on other planets, e.g. Mars, it is necessary to know the limiting physical and chemical parameters of terrestrial life. Therefore the polyextremophile bacterium Deinococcus radiodurans was chosen as test organism for these investigations. For the simulation studies at the Planetary and Space Simulation Facilities (PSI) at DLR, Cologne, Germany, conditions that are present during the southern summer at latitude of 60° on Mars were applied. We could simulate several environmental parameters of Mars in one single experiment: vacuum/low pressure, anoxic atmosphere and diurnal cycles in temperature and relative humidity, energy-rich ultraviolet (UV) radiation as well as shielding by different martian soil analogue materials. These parameters have been applied both single and in different combinations in laboratory experiments. Astonishingly the diurnal Mars-like cycles in temperature and relative humidity affected the viability of D. radiodurans cells quite severely. But the martian UV climate turned out to be the most deleterious factor, though D. radiodurans is red-pigmented due to carotenoids incorporated in its cell wall, which have been assigned not only a possible role as free radical scavenger but also as a UV-protectant. An additional UV-protection was accomplished by mixing the bacteria with nano-sized hematite.

  8. Abrasion of windblown particles on Mars - Erosion of quartz and basaltic sand under simulated Martian conditions

    Science.gov (United States)

    Krinsley, D.; Greeley, R.; Pollack, J. B.

    1979-01-01

    The results of a series of laboratory experiments initiated to simulate Martian eolian erosion are presented. Experiments were conducted under Martian atmospheric pressure and compared to natural eolian sand produced on earth. It is reported that the less dense atmosphere on Mars resulted in more energetic eolian erosion manifested by an slightly higher rate of grain rounding and surface textures that included semicircular depressions termed 'popouts'. It is suggested that physical and chemical weathering may proceed more rapidly on Mars than on earth, given a sufficient supply of water vapor. In addition, clay mineral formations should be facilitated by the presence of large amounts of disrupted material. Finally, it is noted that the disrupted material could increase the ability of the soil to act as a reservoir for water thereby provisionally explaining the large amount of bound water on the surface soil material over much of Mars.

  9. First Results of the Expedition to the Highest Lake on Earth: Studying a Martian Paleolake in Bolivia and the Survival Strategies Developed by Living Organisms

    Science.gov (United States)

    Cabrol, N. A.; Grin, E. A.; McKay, C. P.; Friedmann, I.; Diaz, D. Chong; Demergasso, C.; Kisse, K.; Grigorszky, I.; Friedmann, R. Ocampo; Murbach, M. S.

    2003-01-01

    Between October 16th and November 9th 2002, the first NASA Ames DDF Licancabur multidisciplinary expedition initiated the investigation of the biology and environment for life in the highest lake on Earth located at the summit of the Licancabur volcano (6017 m/20,056 ft) at the boundary of Chile and Bolivia. The low oxygen, low atmospheric pressure, high-UV radiation, average temperature, volcano-tectonic and hydrothermal environment make the site a close analog to Martian paleolakes 3.5 billion years ago. The overall goal of the project is to understand through a series of high altitude scientific expeditions what strategies life is using to defend itself against killer-level UV radiation and environmental extreme conditions at this altitude. Several other lakes are located at 4300 m at the foot of the Licancabur volcano (hereafter named laguna Blanca and Laguna Verde). They were also investigated using identical experiments and methods as for the summit lake in order to compare the results and better understand the evolution of survival strategies at transitioning elevations. The lagunas are geothermally heated and many springs provide water at various temperatures. Sources of heat are also suspected for the summit lake as its surface water temperature was measured during the successful ascent at +6 C in a -9 C ambient crater environment (with a wind chill factor of -25 C with a wind blowing almost constantly). Results of this project are expected to provide critical keys to help searching and identifying potential sites for life (extant/extinct) on Mars and developing instruments, experiments and technologies for future missions.

  10. Survival Potential and Photosynthetic Activity of Lichens Under Mars-Like Conditions: A Laboratory Study

    Science.gov (United States)

    de Vera, Jean-Pierre; Möhlmann, Diedrich; Butina, Frederike; Lorek, Andreas; Wernecke, Roland; Ott, Sieglinde

    2010-03-01

    Lichens were repetitively exposed over 22 days to thermophysical Mars-like conditions at low-and mid-latitudes. The simulated parameters and the experimental setup are described. Natural samples of the lichen Xanthoria elegans were used to investigate their ability to survive the applied Mars-like conditions. The effects of atmospheric pressure, CO2 concentration, low temperature, water availability, and light on Mars were also studied. The results of these experiments indicate that - no significant decrease in the vitality of the lichen occurred after exposure to simulated martian conditions, which was demonstrated by confocal laser scanning microscopy analysis, and - a 95% CO2 atmosphere with 100% humidity, low pressure (partial pressure of CO2 was 600 Pa), and low temperature has a balancing effect on photosynthetic activity as a function of temperature. This means a starting low photosynthetic activity at high CO2 concentrations with Earth-like pressure has a reduction of 60%. But, if the simulated atmospheric pressure is reduced to Mars-like conditions with the maintenance of the same Mars-like 95% CO2 concentration, the photosynthetic activity increases and again reaches similar values as those exhibited under terrestrial atmospheric pressure and concentration. Based on these results, we presume that, in any region on Mars where liquid water might be available, even for short periods of time, a eukaryotic symbiotic organism would have the ability to survive, at least over weeks, and to temporarily photosynthesize.

  11. Visible and Near-IR Reflectance Spectra of Smectite Acquired Under Dry Conditions for Interpretation of Martian Surface Mineralogy

    Science.gov (United States)

    Morris, Richard V.; Achilles, Cherie N; Archer, Paul D.; Graff, Trevor G.; Agresti, David G.; Ming, Douglas W; Golden, Dadi C.; Mertzman, Stanley A.

    2011-01-01

    Visible and near-IR (VNIR) spectra from the MEx OMEGA and the MRO CRISM hyper-spectral imaging instruments have spectral features associated with the H2O molecule and M OH functional groups (M = Mg, Fe, Al, and Si). Mineralogical assignments of martian spectral features are made on the basis of laboratory VNIR spectra, which were often acquired under ambient (humid) conditions. Smectites like nontronite, saponite, and montmorillionite have interlayer H2O that is exchangeable with their environment, and we have acquired smectite reflectance spectra under dry environmental conditions for interpretation of martian surface mineralogy. We also obtained chemical, Moessbauer (MB), powder X-ray diffraction (XRD), and thermogravimetric (TG) data to understand variations in spectral properties. VNIR spectra were recorded in humid lab air at 25-35C, in a dynamic dry N2 atmosphere (50-150 ppmv H2O) after exposing the smectite samples (5 nontronites, 3 montmorillionites, and 1 saponite) to that atmosphere for up to approximately l000 hr each at 25-35C, approximately 105C, and approximately 215C, and after re-exposure to humid lab air. Heating at 105C and 215C for approximately 1000 hr is taken as a surrogate for geologic time scales at lower temperatures. Upon exposure to dry N2, the position and intensity of spectral features associated with M-OH were relatively insensitive to the dry environment, and the spectral features associated with H2O (e.g., approximately 1.90 micrometers) decreased in intensity and are sometimes not detectable by the end of the 215C heating step. The position and intensity of H2O spectral features recovered upon re-exposure to lab air. XRD data show interlayer collapse for the nontronites and Namontmorillionites, with the interlayer remaining collapsed for the latter after re-exposure to lab air. The interlayer did not collapse for the saponite and Ca-montmorillionite. TG data show that the concentration of H2O derived from structural OH was invariant

  12. Antimicrobial treatment improves mycobacterial survival in nonpermissive growth conditions.

    Science.gov (United States)

    Turapov, Obolbek; Waddell, Simon J; Burke, Bernard; Glenn, Sarah; Sarybaeva, Asel A; Tudo, Griselda; Labesse, Gilles; Young, Danielle I; Young, Michael; Andrew, Peter W; Butcher, Philip D; Cohen-Gonsaud, Martin; Mukamolova, Galina V

    2014-05-01

    Antimicrobials targeting cell wall biosynthesis are generally considered inactive against nonreplicating bacteria. Paradoxically, we found that under nonpermissive growth conditions, exposure of Mycobacterium bovis BCG bacilli to such antimicrobials enhanced their survival. We identified a transcriptional regulator, RaaS (for regulator of antimicrobial-assisted survival), encoded by bcg1279 (rv1219c) as being responsible for the observed phenomenon. Induction of this transcriptional regulator resulted in reduced expression of specific ATP-dependent efflux pumps and promoted long-term survival of mycobacteria, while its deletion accelerated bacterial death under nonpermissive growth conditions in vitro and during macrophage or mouse infection. These findings have implications for the design of antimicrobial drug combination therapies for persistent infectious diseases, such as tuberculosis.

  13. Effects of simulated Mars conditions on the survival and growth of Escherichia coli and Serratia liquefaciens.

    Science.gov (United States)

    Berry, Bonnie J; Jenkins, David G; Schuerger, Andrew C

    2010-04-01

    Escherichia coli and Serratia liquefaciens, two bacterial spacecraft contaminants known to replicate under low atmospheric pressures of 2.5 kPa, were tested for growth and survival under simulated Mars conditions. Environmental stresses of high salinity, low temperature, and low pressure were screened alone and in combination for effects on bacterial survival and replication, and then cells were tested in Mars analog soils under simulated Mars conditions. Survival and replication of E. coli and S. liquefaciens cells in liquid medium were evaluated for 7 days under low temperatures (5, 10, 20, or 30 degrees C) with increasing concentrations (0, 5, 10, or 20%) of three salts (MgCl(2), MgSO(4), NaCl) reported to be present on the surface of Mars. Moderate to high growth rates were observed for E. coli and S. liquefaciens at 30 or 20 degrees C and in solutions with 0 or 5% salts. In contrast, cell densities of both species generally did not increase above initial inoculum levels under the highest salt concentrations (10 and 20%) and the four temperatures tested, with the exception that moderately higher cell densities were observed for both species at 10% MgSO(4) maintained at 20 or 30 degrees C. Growth rates of E. coli and S. liquefaciens in low salt concentrations were robust under all pressures (2.5, 10, or 101.3 kPa), exhibiting a general increase of up to 2.5 orders of magnitude above the initial inoculum levels of the assays. Vegetative E. coli cells were maintained in a Mars analog soil for 7 days under simulated Mars conditions that included temperatures between 20 and -50 degrees C for a day/night diurnal period, UVC irradiation (200 to 280 nm) at 3.6 W m(-2) for daytime operations (8 h), pressures held at a constant 0.71 kPa, and a gas composition that included the top five gases found in the martian atmosphere. Cell densities of E. coli failed to increase under simulated Mars conditions, and survival was reduced 1 to 2 orders of magnitude by the interactive

  14. The persistence of a chlorophyll spectral biosignature from Martian evaporite and spring analogues under Mars-like conditions

    Science.gov (United States)

    Stromberg, J. M.; Applin, D. M.; Cloutis, E. A.; Rice, M.; Berard, G.; Mann, P.

    2014-07-01

    Spring and evaporite deposits are considered two of the most promising environments for past habitability on Mars and preservation of biosignatures. Manitoba, Canada hosts the East German Creek (EGC) hypersaline spring complex, and the post impact evaporite gypsum beds of the Lake St. Martin (LSM) impact. The EGC complex has microbial mats, sediments, algae and biofabrics, while endolithic communities are ubiquitous in the LSM gypsum beds. These communities are spectrally detectable based largely on the presence of a chlorophyll absorption band at 670 nm however, the robustness of this feature under Martian surface conditions was unclear. Biological and biology-bearing samples from EGC and LSM were exposed to conditions similar to the surface of present day Mars (high UV flux, 100 mbar, anoxic, CO2 rich) for up to 44 days, and preservation of the 670 nm chlorophyll feature and chlorophyll red-edge was observed. A decrease in band depth of the 670 nm band ranging from ~16 to 80% resulted, with correlations seen in the degree of preservation and the spatial proximity of samples to the spring mound and mineral shielding effects. The spectra were deconvolved to Mars Exploration Rover (MER) Pancam and Mars Science Laboratory (MSL) Mastcam science filter bandpasses to investigate the detectability of the 670 nm feature and to compare with common mineral features. The red-edge and 670 nm feature associated with chlorophyll can be distinguished from the spectra of minerals with features below ~1000 nm, such as hematite and jarosite. However, distinguishing goethite from samples with the chlorophyll feature is more problematic, and quantitative interpretation using band depth data makes little distinction between iron oxyhydroxides and the 670 nm chlorophyll feature. The chlorophyll spectral feature is observable in both Pancam and Mastcam, and we propose that of the proposed EXOMARS Pancam filters, the PHYLL filter is best suited for its detection.

  15. Solar Wind Interaction with the Martian Upper Atmosphere at Early Mars/Extreme Solar Conditions

    Science.gov (United States)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Combi, M. R.

    2014-12-01

    The investigation of ion escape fluxes from Mars, resulting from the solar wind interaction with its upper atmosphere/ionosphere, is important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0 ~ 300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100 km ~ 5 RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model output fields into the 3-D BATS-R-US Mars multi-fluid MHD (MF-MHD) model (100 km ~ 20 RM) that can simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid MHD model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres. This feature allows us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model output fields are used as the input for the multi-fluid MHD model and the M-GITM is used as input into the AMPS exosphere model. In this study, we present M-GITM, AMPS, and MF-MHD calculations (1-way coupled) for 2.5 GYA conditions and/or extreme solar conditions for present day Mars (high solar wind velocities, high solar wind dynamic pressure, and high solar irradiance conditions, etc.). Present day extreme conditions may result in MF-MHD outputs that are similar to 2.5 GYA cases. The crustal field orientations are also considered in this study. By comparing estimates of past ion escape rates with the current ion loss rates to be returned by the MAVEN spacecraft (2013-2016), we can better constrain the

  16. Survival benefits of remote ischemic conditioning in sepsis.

    Science.gov (United States)

    Joseph, Bellal; Khalil, Mazhar; Hashmi, Ammar; Hecker, Louise; Kulvatunyou, Narong; Tang, Andrew; Friese, Randall S; Rhee, Peter

    2017-06-01

    Sepsis remains the leading cause of death in the surgical intensive care unit. Prior studies have demonstrated a survival benefit of remote ischemic conditioning (RIC) in many disease states. The aim of this study was to determine the effects of RIC on survival in sepsis in an animal model and to assess alterations in inflammatory biochemical profiles. We hypothesized that RIC alters inflammatory biochemical profiles resulting in decreased mortality in a septic mouse model. Eight to 12 week C57BL/6 mice received intra-peritoneal injection of 12.5-mg/kg lipopolysaccharide (LPS). Septic animals in the experimental group underwent RIC at 0, 2, and 6 h after LPS by surgical exploration and alternate clamping of the femoral artery. Six 4-min cycles of ischemia-reperfusion were performed. Primary outcome was survival at 5-d after LPS injection. Secondary outcome was to assess the following serum cytokine levels: interferon-γ (IFN-γ), interleukin (IL)-10, IL-1β, and tumor necrosis factoralpha (TNFα) at the baseline before LPS injection, 0 hour after LPS injection, and at 2, 4, 24 hours after induction of sepsis (RIC was performed at 2 h after LPS injection). Kaplan-Meier survival analysis and log-rank test were used. ANOVA test was used to compare cytokine measurements. We performed experiments on 44 mice: 14 sham and 30 RIC mice (10 at each time point). Overall survival was higher in the experimental group compared to the sham group (57% versus 21%; P = 0.02), with the highest survival rate observed in the 2-hour post-RIC group (70%). On Kaplan-Meier analysis, 2-h post-RIC group had increased survival at 5 days after LPS (P = 0.04) with hazard ratio of 0.3 (95% confidence interval = 0.09-0.98). In the RIC group, serum concentrations of IFN-γ, IL-10, IL-1β, and TNFα peaked at 2 h after LPS and then decreased significantly over 24 hours (P sepsis and has the potential for implementation in the clinical practice. Early implementation of RIC may play an

  17. Modular Endoprostheses for Nonneoplastic Conditions: Midterm Complications and Survival.

    Science.gov (United States)

    De Gori, Marco; Scoccianti, Guido; Frenos, Filippo; Bettini, Leonardo; Familiari, Filippo; Gasparini, Giorgio; Beltrami, Giovanni; Cuomo, Pierluigi; De Biase, Pietro; Capanna, Rodolfo

    2016-01-01

    The use of modular endoprostheses is a viable option to manage both tumor resection and severe bone loss due to nonneoplastic conditions such as fracture sequelae, failed osteoarticular grafts, arthroplasty revisions, and periprosthetic fractures. We sought to investigate both midterm complications and failures occurred in 87 patients who underwent a megaprosthetic reconstruction in a nonneoplastic setting. After a mean follow-up of 58 (1-167) months, overall failure-free survival was 91.5% at 1 year, 80% at 2 years, 71.6% at 5 years, and 69.1% at 5 and 10 years. There was no significant difference in the survival rate according to the diagnosis at the index procedure (p = 0.921), nor to the reconstruction site (p = 0.402). The use of megaprostheses in a postneoplastic setting did not affect survival rate in comparison with endoprosthetic reconstruction of pure nonneoplastic conditions (p = 0.851). Perimegaprosthetic infection was the leading complication, occurring in 10 (11.5%) patients and implying a megaprosthetic revision in all but one case. Physicians should consider these results when discussing with patients desired outcomes of endoprosthetic reconstructions of a nonneoplastic disease.

  18. Modular Endoprostheses for Nonneoplastic Conditions: Midterm Complications and Survival

    Directory of Open Access Journals (Sweden)

    Marco De Gori

    2016-01-01

    Full Text Available The use of modular endoprostheses is a viable option to manage both tumor resection and severe bone loss due to nonneoplastic conditions such as fracture sequelae, failed osteoarticular grafts, arthroplasty revisions, and periprosthetic fractures. We sought to investigate both midterm complications and failures occurred in 87 patients who underwent a megaprosthetic reconstruction in a nonneoplastic setting. After a mean follow-up of 58 (1–167 months, overall failure-free survival was 91.5% at 1 year, 80% at 2 years, 71.6% at 5 years, and 69.1% at 5 and 10 years. There was no significant difference in the survival rate according to the diagnosis at the index procedure (p=0.921, nor to the reconstruction site (p=0.402. The use of megaprostheses in a postneoplastic setting did not affect survival rate in comparison with endoprosthetic reconstruction of pure nonneoplastic conditions (p=0.851. Perimegaprosthetic infection was the leading complication, occurring in 10 (11.5% patients and implying a megaprosthetic revision in all but one case. Physicians should consider these results when discussing with patients desired outcomes of endoprosthetic reconstructions of a nonneoplastic disease.

  19. A steamy proposal for Martian clays

    Science.gov (United States)

    Schaefer, Laura

    2017-12-01

    Martian clays present a conundrum: the models proposed to explain their formation require conditions that are not predicted by computational climate simulations. Experiments now suggest an alternative scenario.

  20. Martian Fingerprints

    Science.gov (United States)

    2005-01-01

    9 April 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows patterned ground on the martian northern plains. The circular features are buried meteor impact craters; the small dark dots associated with them are boulders. The dark feature at left center is a wind streak. Location near: 75.1oN, 303.0oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Summer

  1. Molecular Mechanisms of Survival Strategies in Extreme Conditions

    Directory of Open Access Journals (Sweden)

    Federica Migliardo

    2012-12-01

    Full Text Available Today, one of the major challenges in biophysics is to disclose the molecular mechanisms underlying biological processes. In such a frame, the understanding of the survival strategies in extreme conditions received a lot of attention both from the scientific and applicative points of view. Since nature provides precious suggestions to be applied for improving the quality of life, extremophiles are considered as useful model-systems. The main goal of this review is to present an overview of some systems, with a particular emphasis on trehalose playing a key role in several extremophile organisms. The attention is focused on the relation among the structural and dynamic properties of biomolecules and bioprotective mechanisms, as investigated by complementary spectroscopic techniques at low- and high-temperature values.

  2. METAL STRUCTURES SURVIVABILITY ASSESSMENT WHEN SIMULATING SERVICE CONDITIONS

    Directory of Open Access Journals (Sweden)

    O. M. Gibalenko

    2016-04-01

    Full Text Available Purpose. The research is aimed at improving the quality and reliability of measures of primary and secondary protection of metal structures at manufacturing companies, to prolong the service life of cyclically loaded structures of production facilities taking into account the corrosion level of danger. Methodology. Authors proposed to use the principles of process approach for statement and realization of management problems of operational service life in corrosion environments. The principles of ensuring reliability on the level of corrosion danger include justification of stages sequence for survivability assessment of a structural metalwork based on the strategy of DMAIC (define, measure, analyze, improve, control: definitions, measurements, analysis, improvement and monitoring of measures of primary and secondary corrosion protection. Findings. Providing control measures from corrosion according to the criterion of corrosion danger allows providing requirements of reliability of structural metalwork based on calculated provisions of the limiting conditions method and solving the problems of management in technological safety during the expected service life of structural objects. Originality. The developed strategy of maintenance of the industrial facilities on an actual state includes the process approach to resource management by creation of system for the account and the functional controlling, risk analysis and regulation of technological safety in production facilities of the enterprises. Realization of the principles of process approach to management of technological safety at the object level is directed to perfecting of tools and methods of anticorrosive protection, extension of a resource taking into account indexes of survivability (, and justification of program measures to ensure the reliability of enterprises(PER. Practical value. On the basis of process approach to quality and reliability management, generalizations of the

  3. Visible and Near-IR Reflectance Spectra for Smectite, Sulfate And Perchlorate under Dry Conditions for Interpretation of Martian Surface Mineralogy

    Science.gov (United States)

    Morris, R.V.; Ming, W.; Golden, D.C.; Arvidson, R.E.; Wiseman, S.M.; Lichtenberg, K.A.; Cull, S.; Graff, T.G.

    2009-01-01

    Visible and near-IR (VNIR) spectral data for the martian surface obtained from orbit by the MRO-CRISM and OMEGA instruments are interpreted as having spectral signatures of H2O/OH-bearing phases, including smectites and other phyllosilicates, sulfates, and high-SiO2 phases [e.g., 1-4]. Interpretations of martian spectral signatures are based on and constrained by spectra that are obtained in the laboratory on samples with known mineralogical compositions and other physicochemical characteristics under, as appropriate, Mars-like environmental conditions (e.g., temperature, pressure, and humidity). With respect to environmental conditions, differences in the absolute concentration of atmospheric H2O can effect the hydration state and therefore the spectra signatures of smectite phyllosilicates (solvation H2O) and certain sulfates (hydration H2O) [e.g., 5-7]. We report VNIR spectral data acquired under humid (laboratory air) and dry (dry N2 gas) environments for two natural smectites (nontronite API-33A and saponite SapCa-1) to characterize the effect of solvation H2O on spectral properties. We also report spectral data for the thermal dehydration products of (1) melanterite (FeSO4.7H2O) in both air and dry N2 gas and (2) Mg-perchlorate (Mg(ClO4)2.6H2O) in dry N2 environments. Spectral measurements for samples dehydrated in dry N2 were made without exposing them to humid laboratory air.

  4. Winter survival of Scots pine seedlings under different snow conditions.

    Science.gov (United States)

    Domisch, Timo; Martz, Françoise; Repo, Tapani; Rautio, Pasi

    2017-10-10

    Future climate scenarios predict increased air temperatures and precipitation, particularly at high latitudes, and especially so during winter. Soil temperatures, however, are more difficult to predict, since they depend strongly on the fate of the insulating snow cover. 'Rain-on-snow' events and warm spells during winter can lead to thaw-freeze cycles, compacted snow and ice encasement, as well as local flooding. These adverse conditions could counteract the otherwise positive effects of climatic changes on forest seedling growth. In order to study the effects of different winter and snow conditions on young Scots pine (Pinus sylvestris L.) seedlings, we conducted a laboratory experiment in which 80 1-year-old Scots pine seedlings were distributed between four winter treatments in dasotrons: ambient snow cover (SNOW), compressed snow and ice encasement (ICE), flooded and frozen soil (FLOOD) and no snow (NO SNOW). During the winter treatment period and a 1.5-month simulated spring/early summer phase, we monitored the needle, stem and root biomass of the seedlings, and determined their starch and soluble sugar concentrations. In addition, we assessed the stress experienced by the seedlings by measuring chlorophyll fluorescence, electric impedance and photosynthesis of the previous-year needles. Compared with the SNOW treatment, carbohydrate concentrations were lower in the FLOOD and NO SNOW treatments where the seedlings had almost died before the end of the experiment, presumably due to frost desiccation of aboveground parts during the winter treatments. The seedlings of the ICE treatment showed dead needles and stems only above the snow and ice cover. The results emphasize the importance of an insulating and protecting snow cover for small forest tree seedlings, and that future winters with changed snow patterns might affect the survival of tree seedlings and thus forest productivity. © The Author 2017. Published by Oxford University Press. All rights reserved

  5. S.A.M., the Italian Martian Simulation Chamber

    Science.gov (United States)

    Galletta, G.; Ferri, F.; Fanti, G.; D'Alessandro, M.; Bertoloni, G.; Pavarin, D.; Bettanini, C.; Cozza, P.; Pretto, P.; Bianchini, G.; Debei, S.

    2006-12-01

    The Martian Environment Simulator (SAM “Simulatore di Ambiente Marziano”) is a interdisciplinary project of Astrobiology done at University of Padua. The research is aimed to the study of the survival of the microorganisms exposed to the “extreme” planetary environment. The facility has been designed in order to simulate Mars’ environmental conditions in terms of atmospheric pressure, temperature cycles and UV radiation dose. The bacterial cells, contained into dedicated capsules, will be exposed to thermal cycles simulating diurnal and seasonal Martian cycles. The metabolism of the different biological samples will be analysed at different phases of the experiment, to study their survival and eventual activity of protein synthesis (mortality, mutations and capability of DNA reparing). We describe the experimental facility and provide the perspectives of the biological experiments we will perform in order to provide hints on the possibility of life on Mars either autochthonous or imported from Earth.

  6. Martian sub-surface ionising radiation: biosignatures and geology

    Directory of Open Access Journals (Sweden)

    J. M. Ward

    2007-07-01

    Full Text Available The surface of Mars, unshielded by thick atmosphere or global magnetic field, is exposed to high levels of cosmic radiation. This ionising radiation field is deleterious to the survival of dormant cells or spores and the persistence of molecular biomarkers in the subsurface, and so its characterisation is of prime astrobiological interest. Here, we present modelling results of the absorbed radiation dose as a function of depth through the Martian subsurface, suitable for calculation of biomarker persistence. A second major implementation of this dose accumulation rate data is in application of the optically stimulated luminescence technique for dating Martian sediments.

    We present calculations of the dose-depth profile in the Martian subsurface for various scenarios: variations of surface composition (dry regolith, ice, layered permafrost, solar minimum and maximum conditions, locations of different elevation (Olympus Mons, Hellas basin, datum altitude, and increasing atmospheric thickness over geological history. We also model the changing composition of the subsurface radiation field with depth compared between Martian locations with different shielding material, determine the relative dose contributions from primaries of different energies, and discuss particle deflection by the crustal magnetic fields.

  7. Studies on the survival of Ascaris suum eggs under laboratory and simulated field conditions

    NARCIS (Netherlands)

    Gaasenbeek, C.P.H.; Borgsteede, F.H.M.

    1998-01-01

    A series of four experiments was carried out to study the survival of Ascaris suum eggs: in a pig slurry unit on a farm, in the laboratory under anaerobic conditions and different relative humidities (rH), and under simulated field conditions. Survival of eggs in the pig slurry unit was 20% after

  8. Fluvial valleys and Martian palaeoclimates

    Science.gov (United States)

    Gulick, Virginia C.; Baker, Victor R.

    1989-10-01

    Theoretical models of early Martian atmospheric evolution describe the maintenance of a dense CO2 atmosphere and a warm, wet climate until the end of the heavy-bombardment phase of impacting. However, the presence of very young, earthlike fluvial valleys on the northern flank of Alba Patera conflicts with this scenario. Whereas the widespread ancient Martian valleys generally have morphologies indicative of sapping erosion by the slow outflow of subsurface water, the local Alba valleys were probably formed by surface-runoff processes. Because subsurface water flow might be maintained by hydrothermal energy inputs and because surface-runoff valleys developed late in Martian history, it is not necessary to invoke drastically different planet-wide climatic conditions to explain valley development on Mars. The Alba fluvial valleys can be explained by hydrothermal activity or outflow-channel discharges that locally modified the atmosphere, including precipitation and local overland flow on low-permeability volcanic ash.

  9. The viability of native microbial communities in martian environment (model)

    Science.gov (United States)

    Vorobyova, Elena; Cheptcov, Vladimir; Pavlov, Anatolyi; Vdovina, Mariya; Lomasov, Vladimir

    For today the important direction in astrobiology is the experimental simulation of extraterrestrial habitats with the assessment of survivability of microorganisms in such conditions. A new task is to investigate the resistance of native microbial ecosystems which are well adapted to the environment and develop unique protection mechanisms that enable to ensure biosphere formation. The purpose of this research was to study the viability of microorganisms as well as viability of native microbial communities of arid soils and permafrost under stress conditions simulating space environment and martian regolith environment, estimation of duration of Earth like life in the Martian soil. The experimental data obtained give the proof of the preservation of high population density, biodiversity, and reproduction activity under favorable conditions in the Earth analogues of Martian soil - arid soils (Deserts of Israel and Morocco) and permafrost (East Siberia, Antarctica), after the treatment of samples by ionizing radiation dose up to 100 kGy at the pressure of 1 torr, temperature (- 50oC) and in the presence of perchlorate (5%). It was shown that in simulated conditions close to the parameters of the Martian regolith, the diversity of natural bacterial communities was not decreased, and in some cases the activation of some bacterial populations occurred in situ. Our results allow suggesting that microbial communities like those that inhabit arid and permafrost ecosystems on the Earth, can survive at least 500 thousand years under conditions of near surface layer of the Martian regolith. Extrapolation of the data according to the intensity of ionizing radiation to the open space conditions allows evaluating the potential lifespan of cells inside meteorites as 20-50 thousand years at least. In this work new experimental data have been obtained confirming the occurrence of liquid water and the formation of wet soil layer due to sublimation of ice when the temperature of the

  10. Improving the survival of probiotic in simulated conditions and ...

    African Journals Online (AJOL)

    Materials and Methods: Modified citrus pectin-alginate microbeads containing Lactobacillus acidophilus ATCC 4356 was developed. Efficiency of the microbeads was evaluated in simulated conditions of the gastrointestinal tract and in Balb/c mice induced with colon tumor. Genomic identification of faecal lactobacilli ...

  11. Survival of Paramecium caudatum at various pH values and under normoxic and hypoxic conditions.

    Science.gov (United States)

    Heydarnejad, M Saeed

    2008-02-01

    The objective of this study was to determine the survival of Paramecium caudatum, a protozoan ciliate, with different pH under normoxic and hypoxic conditions. P. caudatum was exposed to 18 treatments (in triplicate) of varying pH (4, 4.7, 5.7, 6.7, 7.7, 8.7, 9.7, 10.7 and 11.7) with two different conditions of normoxic and hypoxic. Survival was examined every second day for three weeks. P. caudatum mortality was 100% immediately when exposed to pH 4, 10.7 and 11.7 either in normoxic or hypoxic conditions, whereas at other pH values tested this ciliate could survive mostly under hypoxic conditions. The results suggest that under hypoxic condition, 4.7-6.7 is the best pH range for survival of this species.

  12. Twenty Species of Hypobarophilic Bacteria Recovered from Diverse Soils Exhibit Growth under Simulated Martian Conditions at 0.7 kPa.

    Science.gov (United States)

    Schuerger, Andrew C; Nicholson, Wayne L

    2016-12-01

    Bacterial growth at low pressure is a new research area with implications for predicting microbial activity in clouds and the bulk atmosphere on Earth and for modeling the forward contamination of planetary surfaces like Mars. Here, we describe experiments on the recovery and identification of 20 species of bacterial hypobarophiles (def., growth under hypobaric conditions of approximately 1-2 kPa) in 10 genera capable of growth at 0.7 kPa. Hypobarophilic bacteria, but not archaea or fungi, were recovered from diverse soils, and high numbers of hypobarophiles were recovered from Arctic and Siberian permafrost soils. Isolates were identified through 16S rRNA sequencing to belong to the genera Bacillus, Carnobacterium, Clostridium, Cryobacterium, Exiguobacterium, Paenibacillus, Rhodococcus, Streptomyces, and Trichococcus. The highest population of culturable hypobarophilic bacteria (5.1 × 104 cfu/g) was recovered from Colour Lake soils from Axel Heiberg Island in the Canadian Arctic. In addition, we extend the number of hypobarophilic species in the genus Serratia to six type-strains that include S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. plymuthica, and S. quinivorans. Microbial growth at 0.7 kPa suggests that pressure alone will not be growth-limiting on the martian surface, or in Earth's atmosphere up to an altitude of 34 km. Key Words: Barophile-Extremophilic microorganisms-Habitability-Mars-Special Region. Astrobiology 16, 964-976.

  13. The effects of tree species and site conditions on gypsy moth survival and growth in Michigan

    Science.gov (United States)

    John A. Witter; Michael E. Montgomery; Charley A. Chilcote; Jennifer L. Stoyenoff

    1991-01-01

    In 1987, we began a study to determine the relationships between gypsy moth growth and survival and forest site factors. The major objectives of this study were to determine the (1) relationships between gypsy moth survival and growth and different ecosystem conditions, (2) relationships among egg hatch, host phenology, and distribution of small larvae in the...

  14. Adverse foraging conditions may impact body mass and survival of a high Arctic seabird

    Science.gov (United States)

    Harding, A.M.A.; Welcker, J.; Steen, H.; Hamer, K.C.; Kitaysky, A.S.; Fort, J.; Talbot, S.L.; Cornick, L.A.; Karnovsky, N.J.; Gabrielsen, G.W.; Gremillet, D.

    2011-01-01

    Tradeoffs between current reproduction and future survival are widely recognized, but may only occur when food is limited: when foraging conditions are favorable, parents may be able to reproduce without compromising their own survival. We investigated these tradeoffs in the little auk (Alle alle), a small seabird with a single-egg clutch. During 2005-2007, we examined the relationship between body mass and survival of birds breeding under contrasting foraging conditions at two Arctic colonies. We used corticosterone levels of breeding adults as a physiological indicator of the foraging conditions they encountered during each reproductive season. We found that when foraging conditions were relatively poor (as reflected in elevated levels of corticosterone), parents ended the reproductive season with low body mass and suffered increased post-breeding mortality. A positive relationship between body mass and post-breeding survival was found in one study year; light birds incurred higher survival costs than heavy birds. The results of this study suggest that reproducing under poor foraging conditions may affect the post-breeding survival of long-lived little auks. They also have important demographic implications because even a small change in adult survival may have a large effect on populations of long-lived species. ?? 2011 Springer-Verlag.

  15. Effects of long-term simulated martian conditions on a freeze-dried and homogenized bacterial permafrost community

    DEFF Research Database (Denmark)

    Hansen, Aviaja Anna; Jensen, Lars Liengård; Kristoffersen, Tommy

    2009-01-01

    , freeze-thaw cycles, the atmospheric gas composition, and pressure. The homogenized permafrost cores were subjected to repeated cycles of UV radiation for 3 h followed by 27 h without irradiation. The effects of the simulation conditions on the concentrations of biomolecules; numbers of viable, dead...... and will be a central subject in future investigations. Overall, we conclude that in a stable environment (no wind-/pressure-induced mixing) biological material is efficiently shielded by a 2 cm thick layer of dust, while it is relatively rapidly destroyed in the surface layer, and that biomolecules like proteins...

  16. Survival and resuscitation of ten strains of Campylobacter jejuni and Campylobacter coli under acid conditions

    NARCIS (Netherlands)

    Chaveerach, P.; Huurne, ter A.A.H.M.; Lipman, L.J.A.; Knapen, van F.

    2003-01-01

    The culturability of 10 strains of Campylobacter jejuni and Campylobacter coli was studied after the bacteria were exposed to acid conditions for various periods of time. Campylobacter cells could not survive 2 h under acid conditions (formic acid at pH 4). The 10 Campylobacter strains could not be

  17. Survival

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data provide information on the survival of California red-legged frogs in a unique ecosystem to better conserve this threatened species while restoring...

  18. Measurement of Survival Time in Brachionus Rotifers: Synchronization of Maternal Conditions.

    Science.gov (United States)

    Kaneko, Gen; Yoshinaga, Tatsuki; Gribble, Kristin E; Welch, David M; Ushio, Hideki

    2016-07-22

    Rotifers are microscopic cosmopolitan zooplankton used as models in ecotoxicological and aging studies due to their several advantages such as short lifespan, ease of culture, and parthenogenesis that enables clonal culture. However, caution is required when measuring their survival time as it is affected by maternal age and maternal feeding conditions. Here we provide a protocol for powerful and reproducible measurement of the survival time in Brachionus rotifers following a careful synchronization of culture conditions over several generations. Empirically, poor synchronization results in early mortality and a gradual decrease in survival rate, thus resulting in weak statistical power. Indeed, under such conditions, calorie restriction (CR) failed to significantly extend the lifespan of B. plicatilis although CR-induced longevity has been demonstrated with well-synchronized rotifer samples in past and present studies. This protocol is probably useful for other invertebrate models, including the fruitfly Drosophila melanogaster and the nematode Caenorhabditis elegans, because maternal age effects have also been reported in these species.

  19. Carryover effects and climatic conditions influence the postfledging survival of greater sage-grouse

    Science.gov (United States)

    Blomberg, Erik J.; Sedinger, James S.; Gibson, Daniel; Coates, Peter S.; Casazza, Michael L.

    2014-01-01

    Prebreeding survival is an important life history component that affects both parental fitness and population persistence. In birds, prebreeding can be separated into pre- and postfledging periods; carryover effects from the prefledging period may influence postfledging survival. We investigated effects of body condition at fledging, and climatic variation, on postfledging survival of radio-marked greater sage-grouse (Centrocercus urophasianus) in the Great Basin Desert of the western United States. We hypothesized that body condition would influence postfledging survival as a carryover effect from the prefledging period, and we predicted that climatic variation may mediate this carryover effect or, alternatively, would act directly on survival during the postfledging period. Individual body condition had a strong positive effect on postfledging survival of juvenile females, suggesting carryover effects from the prefledging period. Females in the upper 25th percentile of body condition scores had a postfledging survival probability more than twice that (Φ = 0.51 ± 0.06 SE) of females in the bottom 25th percentile (Φ = 0.21 ± 0.05 SE). A similar effect could not be detected for males. We also found evidence for temperature and precipitation effects on monthly survival rates of both sexes. After controlling for site-level variation, postfledging survival was nearly twice as great following the coolest and wettest growing season (Φ = 0.77 ± 0.05 SE) compared with the hottest and driest growing season (Φ = 0.39 ± 0.05 SE). We found no relationships between individual body condition and temperature or precipitation, suggesting that carryover effects operated independently of background climatic variation. The temperature and precipitation effects we observed likely produced a direct effect on mortality risk during the postfledging period. Conservation actions that focus on improving prefledging habitat for sage-grouse may have indirect benefits

  20. The Mineralogy, Geochemistry, and Redox State of Multivalent Cations During the Crystallization of Primitive Shergottitic Liquids at Various (f)O2. Insights into the (f)O2 Fugacity of the Martian Mantle and Crustal Influences on Redox Conditions of Martian Magmas.

    Science.gov (United States)

    Shearer, C. K.; Bell, A. S.; Burger, P. V.; Papike, J. J.; Jones, J.; Le, L.; Muttik, N.

    2016-01-01

    The (f)O2 [oxygen fugacity] of crystallization for martian basalts has been estimated in various studies to range from IW-1 to QFM+4 [1-3]. A striking geochemical feature of the shergottites is the large range in initial Sr isotopic ratios and initial epsilon(sup Nd) values. Studies by observed that within the shergottite group the (f)O2 [oxygen fugacity] of crystallization is highly correlated with these chemical and isotopic characteristics with depleted shergottites generally crystallizing at reduced conditions and enriched shergottites crystallizing under more oxidizing conditions. More recent work has shown that (f)O2 [oxygen fugacity] changed during the crystallization of these magmas from one order of magnitude in Y980459 (Y98) to several orders of magnitude in Larkman Nunatak 06319. These real or apparent variations within single shergottitic magmas have been attributed to mixing of a xenocrystic olivine component, volatile loss-water disassociation, auto-oxidation during crystallization of mafic phases, and assimilation of an oxidizing crustal component (e.g. sulfate). In contrast to the shergottites, augite basalts such as NWA 8159 are highly depleted yet appear to be highly oxidized (e.g. QFM+4). As a first step in attempting to unravel petrologic complexities that influence (f)O2 [oxygen fugacity] in martian magmas, this study explores the effect of (f)O2 [oxygen fugacity] on the liquid line of descent (LLD) for a primitive shergottite liquid composition (Y98). The results of this study will provide a fundamental basis for reconstructing the record of (f)O2 [oxygen fugacity] in shergottites and other martian basalts, its effect on both mineral chemistries and valence state partitioning, and a means for examining the role of crystallization (and other more complex processes) on the petrologic linkages between olivine-phyric and pyroxene-plagioclase shergottites.

  1. Survival of Wild Adults of Ceratitis capitata (Wiedemann under Natural Winter Conditions in North East Spain

    Directory of Open Access Journals (Sweden)

    E. Peñarrubia-María

    2012-01-01

    Full Text Available The overwintering of the Mediterranean fruit fly (medfly, Ceratitis capitata (Wiedemann at the northern limits of its geographic distribution is not yet well known. With the aim of estimating the survival rate of medfly adults in northeast Spain under natural winter conditions, a two-winter-season trial was carried out. A control was carried out in a climatic chamber at 25°C. The results showed that medfly adults were unable to survive the entire winter season in the Girona area. Climatic conditions, including the daily minimum temperature, daily maximum temperature and the high rainfall, appeared to be involved in adult mortality in winter.

  2. Multiple chronic condition profiles and survival among oldest-old male patients with hip fracture.

    Science.gov (United States)

    Cho, Jinmyoung; Stock, Eileen M; Liao, I-Chia; Zeber, John E; Ahmedani, Brian K; Basu, Rashmita; Quinn, Charlene C; Copeland, Laurel A

    2018-01-01

    To improve understanding of survival among very elderly male patients with surgically repaired hip fractures, this study applied classification techniques to multiple chronic conditions (MCC) then modeled survival by latent class. Veterans Health Administration (VHA)'s electronic medical records on male inpatients age 85-100 years (n=896) with hip fracture diagnosis and repair were used. MCC defined by Charlson and Elixhauser disorders, medications, demographic covariates, and 5 years follow-up survival were included. Latent Class Analysis (LCA) identified three classes based on patterns of MCC, medications, and demographic covariates: Low-comorbidity (16%), High-longevity (55%), and High-comorbidity (29%). Overall, survival censored at 5 years post-op averaged 717days. The Low-comorbidity group was more likely to be Hispanic, less disabled per VHA determination of eligibility for care, with less risk of postoperative emergency department (ED) visit, and taking no prescription medications. The High-longevity group had longer survival. The High-comorbidity group had more MCC, more prescription medications and shorter survival than the other two groups. Accelerated failure time (AFT) modeled associations between MCC and 5-year survival by class. In AFT models, fewer days until first postoperative ED visit was significantly associated with survival across the three classes. About one in male hip fractured veteran patients over the age of 85 had high levels of MCC and ED use and experienced shorter survival. Hip fracture patients with MCC may merit enhanced post-discharge management. Close investigation targeted to MCC and hip fractures is needed to optimize clinical practices for oldest-old patients in community healthcare systems as well as VHA. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Conditional survival for long-term colorectal cancer survivors in the Netherlands: who do best?

    NARCIS (Netherlands)

    Erning, F.N. van; Steenbergen, L.N. van; Lemmens, V.E.; Rutten, H.J.; Martijn, H.; Spronsen, D.J. van; Janssen-Heijnen, M.L.

    2014-01-01

    AIM: With the increase in the number of long-term colorectal cancer (CRC) survivors, there is a growing need for subgroup-specific analysis of conditional survival. METHODS: All 137,030 stage I-III CRC patients diagnosed in the Netherlands between 1989 and 2008 aged 15-89years were selected from the

  4. Variability in survival of Pectinatus cerevisiiphilus, strictly anaerobic bacteria, under different oxygen conditions.

    Science.gov (United States)

    Chowdhury, I; Watier, D; Hornez, J P

    1995-06-01

    Survival of Pectinatus cerevisiiphilus DSM 20466 in pure culture at variable temperatures under different oxygen concentrations was measured. Survival of P. cerevisiiphilus in co-culture with Saccharomyces cerevisiae under both saturated oxygen and brewing conditions was also studied. The survival of strictly anaerobic bacteria to oxygen seems to follow the classical laws of heat resistance. The D(oxy) values of P. cerevisiiphilus , calculated as a function of oxygen level, shows that the oxygen level is important for the survival duration of the bacteria. The temperature greatly influences the oxygen resistance of P. cerevisiiphilus, which increases when the temperature decreases. P. cerevisiiphilus resists better in co-culture than in pure culture under saturated oxygen conditions. Therefore, the oxygenation of the wort does not totally eliminate the risk of beer contamination by this bacterium. Under brewing conditions in co-culture at 8 degrees C, P. cerevisiiphilus grows slowly to reach a final cell concentration up to 10(6) cells/mL in beer, which is undrinkable. Pectinatus is a strictly anaerobic bacterium; however, it is resistant under certain oxygen conditions of incubation. This resistance is considerably higher in the presence of Saccharomyces cerevisiae .

  5. Interactions between formulation and spray drying conditions related to survival of Lactobacillus plantarum WCFS1

    NARCIS (Netherlands)

    Perdana, J.A.; Fox, M.B.; Siwei, C.; Boom, R.M.; Schutyser, M.A.I.

    2014-01-01

    Protective solid carriers are commonly added to probiotic cultures prior to drying. Their formulation is not trivial and depends on the drying conditions applied. In this study, we systematically investigated the influence of formulation parameters on the survival of Lactobacillus plantarum WCFS1

  6. An Electrostatic Precipitator System for the Martian Environment

    Science.gov (United States)

    Calle, C. I.; Mackey, P. J.; Hogue, M. D.; Johansen, M. R.; Phillips, J. R., III; Clements, J. S.

    2012-01-01

    Human exploration missions to Mars will require the development of technologies for the utilization of the planet's own resources for the production of commodities. However, the Martian atmosphere contains large amounts of dust. The extraction of commodities from this atmosphere requires prior removal of this dust. We report on our development of an electrostatic precipitator able to collect Martian simulated dust particles in atmospheric conditions approaching those of Mars. Extensive experiments with an initial prototype in a simulated Martian atmosphere showed efficiencies of 99%. The design of a second prototype with aerosolized Martian simulated dust in a flow-through is described. Keywords: Space applications, electrostatic precipitator, particle control, particle charging

  7. Blowfly puparia in a hermetic container: survival under decreasing oxygen conditions.

    Science.gov (United States)

    Mądra-Bielewicz, Anna; Frątczak-Łagiewska, Katarzyna; Matuszewski, Szymon

    2017-07-01

    Despite widely accepted standards for sampling and preservation of insect evidence, unrepresentative samples or improperly preserved evidence are encountered frequently in forensic investigations. Here, we report the results of laboratory studies on the survival of Lucilia sericata and Calliphora vomitoria (Diptera: Calliphoridae) intra-puparial forms in hermetic containers, which were stimulated by a recent case. It is demonstrated that the survival of blowfly intra-puparial forms inside airtight containers is dependent on container volume, number of puparia inside, and their age. The survival in both species was found to increase with an increase in the volume of air per 1 mg of puparium per day of development in a hermetic container. Below 0.05 ml of air, no insect survived, and above 0.2 ml of air per 1 mg of puparium per day, survival reached its maximum. These results suggest that blowflies reveal a single, general pattern of survival under decreasing oxygen conditions and that this pattern is a product of number of developing insects, their age and the initial amount of available air. Implications for forensic entomology are discussed.

  8. Qualification of Fiber Optic Cables for Martian Extreme Temperature Environments

    Science.gov (United States)

    Ramesham, Rajeshuni; Lindensmith, Christian A.; Roberts, William T.; Rainen, Richard A.

    2011-01-01

    Means have been developed for enabling fiber optic cables of the Laser Induced Breakdown Spectrometer instrument to survive ground operations plus the nominal 670 Martian conditions that include Martian summer and winter seasons. The purpose of this development was to validate the use of the rover external fiber optic cabling of ChemCam for space applications under the extreme thermal environments to be encountered during the Mars Science Laboratory (MSL) mission. Flight-representative fiber optic cables were subjected to extreme temperature thermal cycling of the same diurnal depth (or delta T) as expected in flight, but for three times the expected number of in-flight thermal cycles. The survivability of fiber optic cables was tested for 600 cumulative thermal cycles from -130 to +15 C to cover the winter season, and another 1,410 cumulative cycles from -105 to +40 C to cover the summer season. This test satisfies the required 3 times the design margin that is a total of 2,010 thermal cycles (670 x 3). This development test included functional optical transmission tests during the course of the test. Transmission of the fiber optic cables was performed prior to and after 1,288 thermal cycles and 2,010 thermal cycles. No significant changes in transmission were observed on either of the two representative fiber cables subject through the 3X MSL mission life that is 2,010 thermal cycles.

  9. Hydrogen in Martian Meteorites

    Science.gov (United States)

    Peslier, A. H.; Hervig, R.; Irving, T.

    2017-01-01

    Most volatile studies of Mars have targeted its surface via spacecraft and rover data, and have evidenced surficial water in polar caps and the atmosphere, in the presence of river channels, and in the detection of water bearing minerals. The other focus of Martian volatile studies has been on Martian meteorites which are all from its crust. Most of these studies are on hydrous phases like apatite, a late-stage phase, i.e. crystallizing near the end of the differentiation sequence of Martian basalts and cumulates. Moreover, calculating the water content of the magma a phosphate crystallized from is not always possible, and yet is an essential step to estimate how much water was present in a parent magma and its source. Water, however, is primarily dissolved in the interiors of differentiated planets as hydrogen in lattice defects of nominally anhydrous minerals (olivine, pyroxene, feldspar) of the crust and mantle. This hydrogen has tremendous influence, even in trace quantities, on a planet's formation, geodynamics, cooling history and the origin of its volcanism and atmosphere as well as its potential for life. Studies of hydrogen in nominally anhydrous phases of Martian meteorites are rare. Measuring water contents and hydrogen isotopes in well-characterized nominally anhydrous minerals of Martian meteorites is the goal of our study. Our work aims at deciphering what influences the distribution and origin of hydrogen in Martian minerals, such as source, differentiation, degassing and shock.

  10. The influence of spatiotemporal conditions and personality on survival in reintroductions-evolutionary implications.

    Science.gov (United States)

    Haage, Marianne; Maran, Tiit; Bergvall, Ulrika Alm; Elmhagen, Bodil; Angerbjörn, Anders

    2017-01-01

    Personality exists in non-human animals and can impact fitness. There is, however, a shortage of empirical studies in certain areas within the field, and fundamental evolutionary theory on personality remains largely untested. For example, little is known on how variation in personality is maintained over evolutionary time. Theory suggests that fluctuating selection pressures due to spatiotemporal variation in conditions, e.g. food availability, is a possible mechanism and a few studies have shown that the success of different personality types varies with spatiotemporal conditions. However, it remains unknown whether different mechanisms can maintain personality within a species. Here we use a reintroduction programme for the critically endangered European mink (Mustela lutreola) to test whether multiple personality trait domains (boldness, exploration and sociability) affected survival in two different years and islands. This was done through pre-release personality tests and post-release radio-tracking monitoring. Survival was positively correlated with boldness, whereas the relationship with exploration was either negative or positive depending on year/island. The results show a complex relationship between personality and survival and suggest that exploration can be maintained over evolutionary time via spatiotemporal variation in conditions. However, in contrast to exploration, boldness did not vary spatiotemporally and sociability had no impact on survival. This indicates that different personality trait domains might be maintained by different mechanisms. To date, personality has been studied primarily within behavioural sciences, but through empirical findings we highlight the importance of personality also in ecology and conservation biology.

  11. Longevity and survival curves of Rhinella icterica (Anura, Bufonidae) under laboratory conditions.

    Science.gov (United States)

    Lima, M S C S; Pederassi, J; Souza, C A S

    2014-05-01

    Life tables and survival curves of tadpoles from Rhinella icterica species were studied in the laboratory, under abiotic conditions controlled by a purification filter, a timer and a chiller. The survival curve for larval stage confirms a great mortality trend in the initial stages, which decreases when reaching the mature morphological condition (r = -0.94). Stages 37, 38, 39, 40 and 41 showed gradual values for their age structures, while stages 42, 43 and 44 presented high variations. Based on the results under laboratory conditions, it can be concluded that the maturity of R. icterica tadpoles development between 37 and 44 stages has a negative correlation and their predicted life expectancy is a logarithmic growth curve (y=-761.96Ln(x)+5298.5).

  12. The impact of environmental conditions on Campylobacter jejuni survival in broiler faeces and litter

    Directory of Open Access Journals (Sweden)

    Shaun Smith

    2016-06-01

    Full Text Available Introduction: Campylobacter jejuni is the leading bacterial food-borne pathogen within the European Union, and poultry meat is an important vehicle for its transmission to humans. However, there is limited knowledge about how this organism persists in broiler litter and faeces. The aim of this study was to assess the impact of a number of environmental parameters, such as temperature, humidity, and oxygen, on Campylobacter survival in both broiler litter and faeces. Materials and methods: Used litter was collected from a Campylobacter-negative broiler house after final depopulation and fresh faeces were collected from transport crates. Samples were confirmed as Campylobacter negative according to modified ISO methods for veterinary samples. Both sample matrices were inoculated with 9 log10 CFU/ml C. jejuni and incubated under high (≥85% and low (≤70% relative humidity conditions at three different temperatures (20°C, 25°C, and 30°C under both aerobic and microaerophilic atmospheres. Inoculated litter samples were then tested for Campylobacter concentrations at time zero and every 2 hours for 12 hours, while faecal samples were examined at time zero and every 24 hours for 120 hours. A two-tailed t-test assuming unequal variance was used to compare mean Campylobacter concentrations in samples under the various temperature, humidity, and atmospheric conditions. Results and discussion: C. jejuni survived significantly longer (P≤0.01 in faeces, with a minimum survival time of 48 hours, compared with 4 hours in used broiler litter. C. jejuni survival was significantly enhanced at 20°C in all environmental conditions in both sample matrices tested compared with survival at 25°C and 30°C. In general, survival was greater in microaerophilic compared with aerobic conditions in both sample matrices. Humidity, at the levels examined, did not appear to significantly impact C. jejuni survival in any sample matrix. The persistence of Campylobacter

  13. Growth and Survival of Some Probiotic Strains in Simulated Ice Cream Conditions

    Science.gov (United States)

    Homayouni, A.; Ehsani, M. R.; Azizi, A.; Razavi, S. H.; Yarmand, M. S.

    A Completely Randomized Design (CRD) experiment was applied in triplicates to evaluate the survival of four probiotic strains in simulated ice cream conditions. The growth and survival rate of these probiotic strains (Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium longum) in varying amount of sucrose (10, 15, 20 and 25%), oxygen scavenging components (0.05% L-cysteine and 0.05% L-ascorbate) and temperatures (4 and -20°C) during different periods of time (1, 2 and 3 months) were evaluated in MRS-broth medium. Optical density at 580 nm was used to measure growth. Lactobacilli strains proved to be highly resistant in comparison with Biffidobacteria strains. The viable cell number of Lactobacillus casei in different sucrose concentrations, different oxidoreduction potentials and refrigeration temperature was 1x1010, 2x108 and 5x107 cfu mL-1, respectively. Growth and survival rate of Lactobacillus casei showed to be the highest.

  14. Size-Dependent Consequences of Exogenous Cortisol Manipulation on Overwinter Survival and Condition of Largemouth Bass.

    Science.gov (United States)

    Midwood, Jonathan D; Peiman, Kathryn S; Burt, Aja E W; Sarker, Mohammed Yusuf; Nannini, Michael A; Wahl, David H; Cooke, Steven J

    2017-02-23

    Little is known about the size-dependent consequences of stressors on wild animals, which is particularly relevant during winter where size-specific trends in survival are common. Here, exogenous cortisol manipulation was used to investigate the effect of a physiological challenge on overwinter mortality and spring condition of largemouth bass (Micropterus salmoides) across a range of body sizes. Fish were wild-caught in the fall, assigned into either control or cortisol manipulated treatments, and held in replicated experimental ponds. For bass that survived the winter, length, mass, and health metrics (e.g., gonadosomatic index [GSI], hepatosomatic index [HSI], and water content) were determined in the spring. Winter survival was marginally lower for cortisol treated bass; however, there was no influence of initial length, mass, or condition on overwinter survival. When bass were grouped by size, survival was significantly higher for bass 300-350 mm in length compared to those influence spring health metrics, suggesting that largemouth bass that survived the winter were able to recover from the effects of the cortisol elevation. Initial size and sex were linked to some spring health metrics, with large females having the highest GSI and HSI scores. Overall, results from this study do not support the notion that there are size-dependent responses to cortisol manipulation in a teleost fish. Rather, this type of physiological challenge may modulate the natural rates of winter mortality that are primarily driven by starvation and predation, independent of body size, in subadult and adult largemouth bass. © 2017 Wiley Periodicals, Inc.

  15. Survival and Adaptation of the Thermophilic Species Geobacillus thermantarcticus in Simulated Spatial Conditions

    Science.gov (United States)

    Di Donato, Paola; Romano, Ida; Mastascusa, Vincenza; Poli, Annarita; Orlando, Pierangelo; Pugliese, Mariagabriella; Nicolaus, Barbara

    2017-06-01

    Astrobiology studies the origin and evolution of life on Earth and in the universe. According to the panspermia theory, life on Earth could have emerged from bacterial species transported by meteorites, that were able to adapt and proliferate on our planet. Therefore, the study of extremophiles, i.e. bacterial species able to live in extreme terrestrial environments, can be relevant to Astrobiology studies. In this work we described the ability of the thermophilic species Geobacillus thermantarcticus to survive after exposition to simulated spatial conditions including temperature's variation, desiccation, X-rays and UVC irradiation. The response to the exposition to the space conditions was assessed at a molecular level by studying the changes in the morphology, the lipid and protein patterns, the nucleic acids. G. thermantarcticus survived to the exposition to all the stressing conditions examined, since it was able to restart cellular growth in comparable levels to control experiments carried out in the optimal growth conditions. Survival was elicited by changing proteins and lipids distribution, and by protecting the DNA's integrity.

  16. Survivability of integrated PVDF film sensors to accelerated ageing conditions in aeronautical/aerospace structures

    Science.gov (United States)

    Guzman, E.; Cugnoni, J.; Gmür, T.; Bonhôte, P.; Schorderet, A.

    2013-06-01

    This work validates the use of integrated polyvinylidene fluoride (PVDF) film sensors for dynamic testing, even after being subjected to UV-thermo-hygro-mechanical accelerated ageing conditions. The verification of PVDF sensors’ survivability in these environmental conditions, typically confronted by civil and military aircraft, is the main concern of the study. The evaluation of survivability is made by a comparison of dynamic testing results provided by the PVDF patch sensors subjected to an accelerated ageing protocol, and those provided by neutral non-aged sensors (accelerometers). The available measurements are the time-domain response signals issued from a modal analysis procedure, and the corresponding frequency response functions (FRF). These are in turn used to identify the constitutive properties of the samples by extraction of the modal parameters, in particular the natural frequencies. The composite specimens in this study undergo different accelerated ageing processes. After several weeks of experimentation, the samples exhibit a loss of stiffness, represented by a decrease in the elastic moduli down to 10%. Despite the ageing, the integrated PVDF sensors, subjected to the same ageing conditions, are still capable of providing reliable data to carry out a close followup of these changes. This survivability is a determinant asset in order to use integrated PVDF sensors to perform structural health monitoring (SHM) in the future of full-scale composite aeronautical structures.

  17. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  18. Boron Enrichment in Martian Clay

    Science.gov (United States)

    Nagashima, Kazuhide; Freeland, Stephen J.

    2013-01-01

    We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration. PMID:23762242

  19. A Martian Air Battery Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will investigate an entirely new battery chemistry by developing A Martian Air Battery. Specifically the project will explore the concept of a Martian...

  20. Martian Environment Electrostatic Precipitator

    Science.gov (United States)

    McDougall, Michael Owen

    2016-01-01

    As part of the planned manned mission to Mars, NASA has noticed that shipping oxygen as a part of life support to keep the astronauts alive continuously is overly expensive, and impractical. As such, noting that the Martian atmosphere is 95.37% CO2, NASA chemists noted that one could obtain oxygen from the Martian atmosphere. The plan, as part of a larger ISRU (in-situ resource utilization) initiative, would extract water from the regolith, or the Martian soil which can be electrolyzed by solar panel produced voltage into hydrogen and oxygen. The hydrogen can then be used in the Sabatier reaction with carbon dioxide to produce methane and water producing a net reaction that does not lose water and outputs methane and oxygen for use as rocket fuel and breathing.

  1. Differential Survival of Hyper-Aerotolerant Campylobacter jejuni under Different Gas Conditions

    Directory of Open Access Journals (Sweden)

    Euna Oh

    2017-05-01

    Full Text Available Campylobacter jejuni accounts for a significant number of foodborne illnesses around the world. C. jejuni is microaerophilic and typically does not survive efficiently in oxygen-rich conditions. We recently reported that hyper-aerotolerant (HAT C. jejuni are highly prevalent in retail poultry meat. To assess the capabilities of HAT C. jejuni in foodborne transmission and infection, in this study, we investigated the prevalence of virulence genes in HAT C. jejuni and the survival in poultry meat in atmosphere at a refrigeration temperature. When we examined the prevalence of eight virulence genes in 70 C. jejuni strains from raw poultry meat, interestingly, the frequencies of detecting virulence genes were significantly higher in HAT C. jejuni strains than aerosenstive C. jejuni strains. This suggests that HAT C. jejuni would potentially be more pathogenic than aerosensitive C. jejuni. Under aerobic conditions, aerosensitive C. jejuni survived at 4°C in raw poultry meat for 3 days, whereas HAT C. jejuni survived in poultry meat for a substantially extended time; there was a five-log CFU reduction over 2 weeks. In addition, we measured the effect of other gas conditions, including N2 and CO2, on the viability of HAT C. jejuni in comparison with aerosensitive and aerotolerant strains. N2 marginally affected the viability of C. jejuni. However, CO2 significantly reduced the viability of C. jejuni both in culture media and poultry meat. Based on the results, modified atmosphere packaging using CO2 may help us to control poultry contamination with HAT C. jejuni.

  2. Probiotics improve survival of septic rats by suppressing conditioned pathogens in ascites.

    Science.gov (United States)

    Liu, Da-Quan; Gao, Qiao-Ying; Liu, Hong-Bin; Li, Dong-Hua; Wu, Shang-Wei

    2013-07-07

    To investigate the benefits of probiotics treatment in septic rats. The septic rats were induced by cecal ligation and puncture. The animals of control, septic model and probiotics treated groups were treated with vehicle and mixed probiotics, respectively. The mixture of probiotics included Bifidobacterium longum, Lactobacillus bulgaricus and Streptococcus thermophilus. We observed the survival of septic rats using different amounts of mixed probiotics. We also detected the bacterial population in ascites and blood of experimental sepsis using cultivation and real-time polymerase chain reaction. The severity of mucosal inflammation in colonic tissues was determined. Probiotics treatment improved survival of the rats significantly and this effect was dose dependent. The survival rate was 30% for vehicle-treated septic model group. However, 1 and 1/4 doses of probiotics treatment increased survival rate significantly compared with septic model group (80% and 55% vs 30%, P probiotics treated group compared with septic model group (5.20 ± 0.57 vs 9.81 ± 0.67, P probiotics treated group compared with septic model group (33.3% vs 100.0%, P probiotics treated group were decreased significantly compared with that of septic model group (3.93 ± 0.73 vs 8.80 ± 0.83, P probiotics treatment, there was a decrease in the scores of inflammatory cell infiltration into the intestinal mucosa in septic animals (1.50 ± 0.25 vs 2.88 ± 0.14, P Probiotics improve survival of septic rats by suppressing these conditioned pathogens.

  3. Probiotics improve survival of septic rats by suppressing conditioned pathogens in ascites

    Science.gov (United States)

    Liu, Da-Quan; Gao, Qiao-Ying; Liu, Hong-Bin; Li, Dong-Hua; Wu, Shang-Wei

    2013-01-01

    AIM: To investigate the benefits of probiotics treatment in septic rats. METHODS: The septic rats were induced by cecal ligation and puncture. The animals of control, septic model and probiotics treated groups were treated with vehicle and mixed probiotics, respectively. The mixture of probiotics included Bifidobacterium longum, Lactobacillus bulgaricus and Streptococcus thermophilus. We observed the survival of septic rats using different amounts of mixed probiotics. We also detected the bacterial population in ascites and blood of experimental sepsis using cultivation and real-time polymerase chain reaction. The severity of mucosal inflammation in colonic tissues was determined. RESULTS: Probiotics treatment improved survival of the rats significantly and this effect was dose dependent. The survival rate was 30% for vehicle-treated septic model group. However, 1 and 1/4 doses of probiotics treatment increased survival rate significantly compared with septic model group (80% and 55% vs 30%, P probiotics treated group compared with septic model group (5.20 ± 0.57 vs 9.81 ± 0.67, P probiotics treated group compared with septic model group (33.3% vs 100.0%, P probiotics treated group were decreased significantly compared with that of septic model group (3.93 ± 0.73 vs 8.80 ± 0.83, P probiotics treatment, there was a decrease in the scores of inflammatory cell infiltration into the intestinal mucosa in septic animals (1.50 ± 0.25 vs 2.88 ± 0.14, P Probiotics improve survival of septic rats by suppressing these conditioned pathogens. PMID:23840152

  4. Assessing survival of dairy propionibacteria in gastrointestinal conditions and adherence to intestinal epithelia.

    Science.gov (United States)

    Zárate, Gabriela; González, Silvia; Chaia, Adriana Pérez

    2004-01-01

    The genus Propionibacterium consists of two principal groups, cutaneous and classical or dairy. Cutaneous species are predominant members of the microbial population of human skin and have also been isolated from the feces of humans and other vertebrate animals. They are often considered opportunistic organisms and have been occasionally associated with infections in humans. Dairy propionibacteria are microorganisms extensively used in the industry for manufacture of Swiss-type cheeses and biological production of propionic acid and vitamin B12. They can be isolated from soil, vegetables, silage, raw milk, and dairy products such as kefir and different cheeses with "eyes."In the last decade, several studies have demonstrated probiotic properties for members of the genus Propionibacterium. The effects claimed are based on the production of bacteriocins, vitamins, stimulation of growth of other colonic bacteria like bifidobacteria, beneficial modification of the composition and metabolic activities of the intestinal microflora, immunomodulation, and antimutagenic activity. It is thought that to produce many of these health benefits, the probiotic microorganisms must be able to survive the transit through the hostile conditions of the gastrointestinal tract (GIT) and remain at high levels in the intestine, avoiding removal by peristaltic contractions of the gut. In this sense, microorganisms with a short generation time or the ability to adhere to the intestinal mucosa will survive for prolonged periods in the body of the host. Therefore, two desirable properties for probiotic microorganisms are (1) resistance to gastric acidity, bile, and pancreatic enzymes; and (2) adhesion ability to mucosal surfaces. Dairy bacteria are traditionally not considered to persist as normal inhabitants of the human intestinal tract. Therefore, survival under GIT conditions and adherence are important properties to be considered, and tests to study them would be useful tools. In the

  5. Effect of encapsulation of selected probiotic cell on survival in simulated gastrointestinal tract condition

    Directory of Open Access Journals (Sweden)

    Hasiah Ayama

    2014-06-01

    Full Text Available The health benefits of probiotic bacteria have been led to their increasing use in foods. Encapsulation has been investigated to improve their survival. In this study, the selection, encapsulation and viability of lactic acid bacteria (LAB with probiotic properties in simulated gastrointestinal tract (GIT condition were investigated. One hundred and fifty isolates of LAB were obtained from 30 samples of raw cow and goat milk and some fermented foods. Nine isolates could survive under GIT condition and only 3 isolates exhibited an antimicrobial activity against all food-borne pathogenic bacteria. Among them, 2 isolates (CM21 and CM53 exhibited bile salt hydrolase activity on glycocholate and glycodeoxycholate agar plates and were identified as Lactobacillus plantarum. CM53 was selected for encapsulation using 1-3% alginate and 2% Hi-maize resistant starch by emulsion system. Viability and releasing ability of encapsulated CM53 in simulated GIT condition was increased in accordance to the alginate concentration and incubation time, respectively.

  6. Survival of Pochonia chlamydosporia on the soil surface after different exposure intervals at ambient conditions.

    Science.gov (United States)

    Fernandes, Rafael Henrique; Lopes, Everaldo Antônio; Borges, Darlan Ferreira; Bontempo, Amanda Ferreira; Zanuncio, José Cola; Serrão, José Eduardo

    Exposure of the nematophagous fungus Pochonia chlamydosporia to solar radiation and elevated temperatures before being incorporated into the soil can reduce its survival and efficiency as biocontrol agent. A field experiment was carried out to assess the effect of the exposure period on the viability of P. chlamydosporia applied on the soil surface. A commercial bionematicide based on P. chlamydosporia was sprayed on soil, and soil samples were collected before and at 0, 30, 60, 90, 120, and 150min after fungal application. Relative humidity (RH), the irradiance (IR), air temperature (AT), and soil temperature (ST) were recorded. The number of P. chlamydosporia colony forming units (CFUs) was evaluated after 20 days of incubation. P. chlamydosporia survival decreased over the time of exposure on the soil surface. Overall, the number of CFUs decreased by more than 90% at 150min after application. Exposure to RH ≥61%, ST and AT between 25-35°C and 19-29°C, and IR between 1172 and 2126μmol of photons m -2 s -1 induced a negative exponential effect on the survival of the fungus over the time. Exposure to climatic conditions on the soil surface reduces P. chlamydosporia viability. Copyright © 2017 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Survival and electrotransformation of Pseudomonas syringae strains under simulated cloud-like conditions.

    Science.gov (United States)

    Blanchard, Laurine S; Monin, Anaïs; Ouertani, Hounaïda; Touaibia, Lamia; Michel, Elisa; Buret, François; Simonet, Pascal; Morris, Cindy E; Demanèche, Sandrine

    2017-05-01

    To diversify their genetic material, and thereby allow adaptation to environmental disturbances and colonization of new ecological niches, bacteria use various evolutionary processes, including the acquisition of new genetic material by horizontal transfer mechanisms such as conjugation, transduction and transformation. Electrotransformation mediated by lightning-related electrical phenomena may constitute an additional gene-transfer mechanism occurring in nature. The presence in clouds of bacteria such as Pseudomonas syringae capable of forming ice nuclei that lead to precipitation, and that are likely to be involved in triggering lightning, led us to postulate that natural electrotransformation in clouds may contribute to the adaptive potential of these bacteria. Here, we quantify the survival rate of 10 P. syringae strains in liquid and icy media under such electrical pulses and their capacity to acquire exogenous DNA. In comparison to two other bacteria (Pseudomonas sp. N3 and Escherichia coli TOP10), P. syringae CC0094 appears to be best adapted for survival and for genetic electrotransformation under these conditions, which suggests that this bacterium would be able to survive and to get a boost in its adaptive potential while being transported in clouds and falling back to Earth with precipitation from storms. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Effect of Conditioning Treatments on the Survival of Radopholus similis at High Temperatures.

    Science.gov (United States)

    Arcinas, A; Sipes, B S; Hara, A H; Tsang, M M C

    2005-09-01

    Heat treatments are an environmentally safe method for eliminating quarantine pests from tropical foliage. Conditioning heat treatments can induce thermotolerance against subsequent and otherwise phytotoxic temperatures in tropical foliage, allowing heat treatments to be even more effective. However, if thermotolerance is also induced in nematodes of quarantine significance like Radopholus similis, heat treatments would be rendered ineffective. A lethal thermal death point (LT(99.9)) was established for R. similis by recording mortality at 25 (control temperature), 43 degrees C, 45 degrees C, 47 degrees C, or 49 degrees C after a 0, 1-, 2-, 4-, 6-, 8-, 10-, 12-, or 15-minute exposure. In a second experiment, nematodes were conditioned at 35, 40, or 45 degrees C for 0, 15, 30, 60, 120, and 180 minutes, allowed to rest for 3 hours, and then challenged at 47 degrees C for 5 minutes. No nematodes survived the challenge heat treatment; rather, nematode mortality was hastened by the conditioning treatment itself. In a third experiment, R. similis inside anthurium roots were conditioned at 25 degrees C or 40 degrees C for 15 minutes and then treated at 45 degrees C for up to 8 minutes. Mortality of conditioned and unconditioned nematodes was similar (P > 0.1). Conditioning treatments increase plant thermotolerance but do not induce thermotolerance in R. similis. Heat treatments have promise as disinfection protocols for quarantines.

  9. Improvement of piglet survival rate in relation to farrowing systems and conditions.

    Science.gov (United States)

    Aumaitre, A; Le Dividich, J

    1984-01-01

    Two experiments were carried out in the same farrowing house with the aim of comparing the efficiency of two types of floors and in order to estimate the effect of bedding material on the performance of newborn piglets. In addition, the productivity data of our sow herd as well as those of the national herd, were analysed in order to study the effect of the farrowing system and piglet maturity at birth on the survival rate of the newborn. The main results clearly show the detrimental effect on piglet survival of using slatted floors at farrowing. Furthermore the mode of sow tethering during parturition directly affects the piglets losses between birth and weaning, i.e. 2.03 piglets/litter for tethered sows, 2.17 for caged sows, 2.30 piglets when using farrowing rails. Use of a bedding material has a positive influence on the survival rate: 83.1% for straw, 78.5% for shredded paper versus 68.5% in the case of an insulated concrete floor. Rearing of newborn piglets in a cold environment leads to a drop in the rectal temperature, a poor body carbohydrate utilization and a decrease in colostrum intake. This results in a poor immunity, a low survival rate and a growth rate depression. Search for optimal environmental conditions for the newborn piglet is more important than for the sow. An adequate management of farrowing houses is recommended involving tethering of the sows, extra heating of the pens when the piglets are born and during their first 3 weeks of life.

  10. Growth, survival, proliferation and pathogenesis of Listeria monocytogenes under low oxygen or anaerobic conditions: a review.

    Science.gov (United States)

    Lungu, B; Ricke, S C; Johnson, M G

    2009-01-01

    Listeria monocytogenes is a Gram positive facultative anaerobe that causes listeriosis, a disease that mainly affects the immune-compromised, the elderly, infants and pregnant women. In the susceptible immune challenged population, listeriosis is very severe and has a fatality rate of up to 30%. Control of L. monocytogenes is difficult due to its: 1) widespread presence in the environment, 2) intrinsic physiological resistance, 3) ability to adapt to external stresses and 4) ability to grow at a wide range of temperatures. L. monocytogenes encounters anaerobic conditions in the external environment as well as during pathogenesis. Although L. monocytogenes is a facultative anaerobe, the differential effects of O(2) and oxidation-reduction potential on the multiplication of L. monocytogenes have not been established. In addition, most laboratory studies to determine the growth, survival and persistence of this pathogen in foods as well as in the environment have emphasized the response of this pathogen under aerobic conditions. Consequently, this has led to a limited understanding of the metabolic and physiological responses of L. monocytogenes in low oxygen environments. Therefore, the objective of our review was to highlight the progress that has been made in L. monocytogenes research with emphasis on the role of low oxygen and/or anaerobiosis in the growth, survival and proliferation of this pathogen in the environment as well as during pathogenesis.

  11. Survival of B. Horneckiae Spores Under Ground-simulated Space Conditions

    Science.gov (United States)

    Schanche, Bradley

    2012-01-01

    To prevent forward contamination and maintain the scientific integrity of future life detection missions, it is important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory spacecraft and landing vehicles. Among the organisms isolated from spacecraft-associated habitats, spore-forming microbes are highly resistant to various physical and chemical conditions, which include ionizing and UV radiation, desiccation and oxidative stress, and the harsh environment of outer space or planetary surfaces. Recently a radiation resistant, spore forming bacterial isolate, Bacillus horneckiae, was isolated from a clean room of the Kennedy Space Center where the Phoenix spacecraft was assembled. The exceptionally high tolerance of extreme conditions demonstrated by sporeforming bacteria highlighted the need to assess the viability of these microbes in situ (in real) space. The proposed BOSS (Biofilm Organisms Surfing Space) project aims to understand the mechanisms by which biofilm forming organisms, such as B. horneckiae, will potentially be able to withstand harsh space conditions. As previously stated, the spore producing ability of these species gives them increased survivability to harsh conditions. Some of the spores will have the protective exosporium layer artificially removed before the test to determine if the existence of this layer significantly changes the survivability during the mission. In preparation for that experiment, we analyzed spores which were exposed during a ground simulation, the EXPOSE R2 Biofilm Organisms Surfing Space (BOSS). Previous to exposure, spores were deposited onto spacecraft grade aluminum coupons in a spore suspension calculated to contain between 10(exp 7) and 10(exp 8) spores. This precursor series will be used to establish a baseline survivability function for comparison with the future flight tests during EXPOSE-R. For each coupon, a 10% polyvinyl alcohol (PVA) film was applied and peeled

  12. Survival of Ixodes ricinus (Acari: Ixodidae) nymphs under cold conditions is negatively influenced by frequent temperature variations.

    Science.gov (United States)

    Herrmann, Coralie; Gern, Lise

    2013-09-01

    In this study, we tested the survival of Ixodes ricinus under cold conditions in the laboratory. We investigated how the frequency of temperature variations (from -5 °C or -10 °C to 13 °C), and infection with Borrelia burgdorferi sensu lato (s.l.) influenced survival of questing nymphs collected in spring and autumn 2011. In experiment 1, survival of 1760 nymphs was tested at -10 °C over a short period of time to simulate very cold winter conditions. In experiment 2, survival of 1600 nymphs was tested under cold condition (-5 °C) over a long period of time to simulate common winter conditions. Ticks used for survival tests at -5 °C were screened for Borrelia by quantitative PCR, and genospecies identification was achieved by reverse line blotting. Tick age and frequency of temperature variations had a highly significant effect on I. ricinus survival while Borrelia infection was marginally significant. Hence, survival rate was higher in younger (autumn) than older (spring) nymphs and in nymphs exposed to low rather than high-frequency temperature variations. Borrelia-infected ticks tended to survive better than their uninfected counterparts. These findings suggest that in nature (i) frequent temperature changes in winter threaten tick survival more importantly than very low temperatures, (ii) older (spring) ticks are less resistant to cold than younger (autumn) individuals, and (iii) Borrelia infection plays a marginal role in I. ricinus survival during winter conditions. Copyright © 2013 Elsevier GmbH. All rights reserved.

  13. Demonstrating Martian Gravity

    CERN Document Server

    Pirkola, Patrik

    2016-01-01

    The surface gravity on Mars is smaller than the surface gravity on Earth, resulting in longer falling times. This effect can be simulated on Earth by taking advantage of air resistance and buoyancy, which cause low density objects to fall slowly enough to approximate objects falling on the surface of Mars. We describe a computer simulation based on an experiment that approximates Martian gravity, and verify our numerical results by performing the experiment.

  14. The Martian magnetic field

    Science.gov (United States)

    Russell, C. T.

    1979-01-01

    The paper presents an overview of the Martian magnetic field measurements and the criticisms made of them. The measurements of the Mars 2, 3, and 5 spacecraft were interpreted by Dolginov et al. (1976, 1978) to be consistent with an intrinsic planetary magnetic moment of 2.5 times 10 to the 22nd power gauss cu cm, basing this result on the apparent size of the obstacle responsible for deflecting the solar wind and an apparent encounter of the spacecraft with the planetary field. It is shown that if the dependence of the Martian magnetic moment on the rotation rate was linear, the estimate of the moment would be far larger than reported by Dolginov et al. An upper limit of 250 km is calculated for the dynamo radius using the similarity law, compared with 500 km obtained by Dolginov et al. It is concluded that the possible strength of a Martian dynamo is below expectations, and it is likely that the Mars dynamo is not presently operative.

  15. Survival of Lactobacillus rhamnosus GG as influenced by storage conditions and product matrixes.

    Science.gov (United States)

    Klu, Yaa Asantewaa Kafui; Williams, Jonathan H; Phillips, Robert D; Chen, Jinru

    2012-12-01

    Mortality resulting from diarrhea especially that occurs in children younger than 5 y of age ranks 3rd among all deaths caused by infectious diseases worldwide. Probiotics such as Lactobacillus rhamnosus GG are clinically shown to effectively reduce the incidence of diarrhea in children. A food substrate is one of the major factors regulating the colonization of microorganisms in human gastrointestinal tracts. Peanut butter is a nutritious, low-moisture food that could be a carrier for probiotics. In this study, we observed the influence of storage conditions and product matrixes on the survival of L. rhamnosus GG. Cells of L. rhamnosus GG were inoculated into full fat or reduced fat peanut butter at 10(7) CFU/g. Inoculated peanut butter was stored at 4, 25, or 37 °C for 48 wk. Samples were drawn periodically to determine the populations of L. rhamnosus GG. Results showed that there was no significant decrease in the viable counts of L. rhamnosus GG in products stored 4 °C. The survivability of L. rhamnosus GG decreased with increasing storage temperature and time. Product matrixes did not significantly affect the survival of L. rhamnosus GG except at 37 °C. Populations of L. rhamnosus GG were preserved at >6 logs in products stored at 4 °C for 48 wk and at 25 °C for 23 to 27 wk. At 37 °C, the 6-log level could not be maintained for even 6 wk. The results suggest that peanut butter stored at 4 and 25 °C could serve as vehicles to deliver probiotics. © 2012 Institute of Food Technologists®

  16. Osteocalcin protects pancreatic beta cell function and survival under high glucose conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kover, Karen, E-mail: kkover@cmh.edu [Division of Endocrine/Diabetes, Children' s Mercy Hospital & Clinics, Kansas City, MO 64108 (United States); University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108 (United States); Yan, Yun; Tong, Pei Ying; Watkins, Dara; Li, Xiaoyu [Division of Endocrine/Diabetes, Children' s Mercy Hospital & Clinics, Kansas City, MO 64108 (United States); University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108 (United States); Tasch, James; Hager, Melissa [Kansas City University Medical Biosciences, Kansas City, MO (United States); Clements, Mark; Moore, Wayne V. [Division of Endocrine/Diabetes, Children' s Mercy Hospital & Clinics, Kansas City, MO 64108 (United States); University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108 (United States)

    2015-06-19

    Diabetes is characterized by progressive beta cell dysfunction and loss due in part to oxidative stress that occurs from gluco/lipotoxicity. Treatments that directly protect beta cell function and survival in the diabetic milieu are of particular interest. A growing body of evidence suggests that osteocalcin, an abundant non-collagenous protein of bone, supports beta cell function and proliferation. Based on previous gene expression data by microarray, we hypothesized that osteocalcin protects beta cells from glucose-induced oxidative stress. To test our hypothesis we cultured isolated rat islets and INS-1E cells in the presence of normal, high, or high glucose ± osteocalcin for up to 72 h. Oxidative stress and viability/mitochondrial function were measured by H{sub 2}O{sub 2} assay and Alamar Blue assay, respectively. Caspase 3/7 activity was also measured as a marker of apoptosis. A functional test, glucose stimulated insulin release, was conducted and expression of genes/protein was measured by qRT-PCR/western blot/ELISA. Osteocalcin treatment significantly reduced high glucose-induced H{sub 2}O{sub 2} levels while maintaining viability/mitochondrial function. Osteocalcin also significantly improved glucose stimulated insulin secretion and insulin content in rat islets after 48 h of high glucose exposure compared to untreated islets. As expected sustained high glucose down-regulated gene/protein expression of INS1 and BCL2 while increasing TXNIP expression. Interestingly, osteocalcin treatment reversed the effects of high glucose on gene/protein expression. We conclude that osteocalcin can protect beta cells from the negative effects of glucose-induced oxidative stress, in part, by reducing TXNIP expression, thereby preserving beta cell function and survival. - Highlights: • Osteocalcin reduces glucose-induced oxidative stress in beta cells. • Osteocalcin preserves beta cell function and survival under stress conditions. • Osteocalcin reduces glucose

  17. Effect of oxygen stress on growth and survival of Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes under different storage conditions.

    Science.gov (United States)

    Al-Qadiri, Hamzah; Sablani, Shyam S; Ovissipour, Mahmoudreza; Al-Alami, Nivin; Govindan, Byju; Rasco, Barbara

    2015-04-01

    This study investigated the growth and survival of three foodborne pathogens (Clostridium perfringens, Campylobacter jejuni, and Listeria monocytogenes) in beef (7% fat) and nutrient broth under different oxygen levels. Samples were tested under anoxic (perfringens could grow in beef at 22 °C, with an increase of approximately 5 log under anoxic conditions and a 1-log increase under microoxic conditions. However, C. perfringens could not survive in beef held at 7 °C under microoxic and oxic storage conditions after 14 days. In an anoxic environment, C. perfringens survived in beef samples held at 7 °C, with a 1-log reduction. A cell decline was observed at 2 log under these conditions, with no surviving cells at the 1-log level. However, the results show that C. jejuni under microoxic conditions survived with declining cell numbers. Significant increases in L. monocytogenes (5 to 7 log) were observed in beef held at 22 °C for 5 days, with the lowest levels recovered under anoxic conditions. L. monocytogenes in refrigerated storage increased by a factor of 2 to 4 log. It showed the greatest growth under oxic conditions, with significant growth under anoxic conditions. These findings can be used to enhance food safety in vacuum-packed and modified atmosphere-packaged food products.

  18. The agony of choice: how plants balance growth and survival under water-limiting conditions.

    Science.gov (United States)

    Claeys, Hannes; Inzé, Dirk

    2013-08-01

    When confronted with water limitation, plants actively reprogram their metabolism and growth. Recently, it has become clear that growing tissues show specific and highly dynamic responses to drought, which differ from the well-studied responses in mature tissues. Here, we provide an overview of recent advances in understanding shoot growth regulation in water-limiting conditions. Of special interest is the balance between maintained growth and competitiveness on the one hand and ensured survival on the other hand. A number of master regulators controlling this balance have been identified, such as DELLAs and APETALA2/ETHYLENE RESPONSE FACTOR-type transcription factors. The possibilities of engineering or breeding crops that maintain growth in periods of mild drought, while still being able to activate protective tolerance mechanisms, are discussed.

  19. The Agony of Choice: How Plants Balance Growth and Survival under Water-Limiting Conditions1

    Science.gov (United States)

    Claeys, Hannes; Inzé, Dirk

    2013-01-01

    When confronted with water limitation, plants actively reprogram their metabolism and growth. Recently, it has become clear that growing tissues show specific and highly dynamic responses to drought, which differ from the well-studied responses in mature tissues. Here, we provide an overview of recent advances in understanding shoot growth regulation in water-limiting conditions. Of special interest is the balance between maintained growth and competitiveness on the one hand and ensured survival on the other hand. A number of master regulators controlling this balance have been identified, such as DELLAs and APETALA2/ETHYLENE RESPONSE FACTOR-type transcription factors. The possibilities of engineering or breeding crops that maintain growth in periods of mild drought, while still being able to activate protective tolerance mechanisms, are discussed. PMID:23766368

  20. Chlorine Abundances in Martian Meteorites

    Science.gov (United States)

    Bogard, D.D.; Garrison, D.H.; Park, J.

    2009-01-01

    Chlorine measurements made in martian surface rocks by robotic spacecraft typically give Chlorine (Cl) abundances of approximately 0.1-0.8%. In contrast, Cl abundances in martian meteorites appear lower, although data is limited, and martian nakhlites were also subjected to Cl contamination by Mars surface brines. Chlorine abundances reported by one lab for whole rock (WR) samples of Shergotty, ALH77005, and EET79001 range 108-14 ppm, whereas Cl in nakhlites range 73-1900 ppm. Measurements of Cl in various martian weathering phases of nakhlites varied 0.04-4.7% and reveal significant concentration of Cl by martian brines Martian meteorites contain much lower Chlorine than those measured in martian surface rocks and give further confirmation that Cl in these surface rocks was introduced by brines and weathering. It has been argued that Cl is twice as effective as water in lowering the melting point and promoting melting at shallower martian depths, and that significant Cl in the shergottite source region would negate any need for significant water. However, this conclusion was based on experiments that utilized Cl concentrations more analogous to martian surface rocks than to shergottite meteorites, and may not be applicable to shergottites.

  1. Home range, body condition, and survival of rehabilitated raccoons (Procyon lotor) during their first winter.

    Science.gov (United States)

    McWilliams, Molly; Wilson, James A

    2015-01-01

    The effects of raccoon (Procyon lotor) rehabilitation on postrelease survivorship are unknown. Raccoon rehabilitation success was measured as differences in prewinter body condition, home range size, distance to manmade structures, and during-winter survival between raccoons in the wild and those who have been rehabilitated. Prewinter body condition did not differ between wild and rehabilitated raccoons, but there was a trend for rehabilitated raccoons to have better body conditions. There was no difference between wild and rehabilitated raccoon adaptive kernel (AK) home range for 95% and 90% AK home ranges, or for core (50% AK) use areas. There was no sex difference in distance traveled from the release site within rehabilitated raccoons. However, rehabilitated raccoons were found significantly closer (49.4 ± 4.7 m) to manmade structures than wild raccoons (92.2 ± 14.4 m), and female raccoons were found significantly closer (64.8 ± 4.5 m) to manmade structures than male raccoons (72.3 ± 17.6 m). The results of this study indicate that raccoons can be successfully rehabilitated, but they may occupy habitat closer to manmade structures than wild raccoons.

  2. Protein kinase G confers survival advantage to Mycobacterium tuberculosis during latency-like conditions.

    Science.gov (United States)

    Khan, Mehak Zahoor; Bhaskar, Ashima; Upadhyay, Sandeep; Kumari, Pooja; Rajmani, Raju S; Jain, Preeti; Singh, Amit; Kumar, Dhiraj; Bhavesh, Neel Sarovar; Nandicoori, Vinay Kumar

    2017-09-29

    Protein kinase G (PknG), a thioredoxin-fold-containing eukaryotic-like serine/threonine protein kinase, is a virulence factor in Mycobacterium tuberculosis, required for inhibition of phagolysosomal fusion. Here, we unraveled novel functional facets of PknG during latency-like conditions. We found that PknG mediates persistence under stressful conditions like hypoxia and abets drug tolerance. PknG mutant displayed minimal growth in nutrient-limited conditions, suggesting its role in modulating cellular metabolism. Intracellular metabolic profiling revealed that PknG is necessary for efficient metabolic adaptation during hypoxia. Notably, the PknG mutant exhibited a reductive shift in mycothiol redox potential and compromised stress response. Exposure to antibiotics and hypoxic environment resulted in higher oxidative shift in mycothiol redox potential of PknG mutant compared with the wild type. Persistence during latency-like conditions required kinase activity and thioredoxin motifs of PknG and is mediated through phosphorylation of a central metabolic regulator GarA. Finally, using a guinea pig model of infection, we assessed the in vivo role of PknG in manifestation of disease pathology and established a role for PknG in the formation of stable granuloma, hallmark structures of latent tuberculosis. Taken together, PknG-mediated GarA phosphorylation is important for maintenance of both mycobacterial physiology and redox poise, an axis that is dispensable for survival under normoxic conditions but is critical for non-replicating persistence of mycobacteria. In conclusion, we propose that PknG probably acts as a modulator of latency-associated signals. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Predicting time to recall in patients conditionally released from a secure forensic hospital: A survival analysis.

    Science.gov (United States)

    Jewell, Amelia; Cocks, Christopher; Cullen, Alexis E; Fahy, Tom; Dean, Kimberlie

    2018-01-17

    The recall of conditionally discharged forensic patients in England is a formal order from the Ministry of Justice under the Mental Health Act (1983) which has the power to revoke conditional release and direct readmission to hospital. Recall has significant implications for the individual and for hospital services, but despite this, little is known about predictors of recall for forensic patients. We examined the rate of recall for 101 patients conditionally discharged from medium secure forensic inpatient services between 2007 and 2013. Demographic, clinical, and forensic factors were examined as possible predictors of time to recall using Cox regression survival techniques. Conditionally discharged patients were followed for an average of 811 days, during which 45 (44.5%) were recalled to hospital. Younger age (HR 1.89; 95% CI 1.02-3.49; p = 0.04), non-white ethnicity (HR 3.44; 95% CI 1.45-8.13), substance abuse history (HR 2.52; 95% CI 1.17-5.43), early violence (HR 1.90; 95% CI 1.03-3.50), early childhood maladjustment (HR 1.92; 95% CI 1.01-3.68), treatment with a depot medication (HR 2.17; 95% CI 1.14-4.11), being known to mental health services (HR 3.44; 95% CI 1.06-11.16), and a psychiatric admission prior to the index admission (HR 2.44; 95% CI 1.08-5.52) were significantly associated with a shorter time to recall. Treatment with clozapine reduced the risk of recall to hospital (HR 0.40; 95% CI 0.20-0.79). Time to recall can be predicted by a range of factors that are readily available to clinical teams. Further research is required to determine if targeted interventions can modify the likelihood or time to recall for conditionally released forensic patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  4. Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates on Mars

    Science.gov (United States)

    Schuerger, A. C.; Kern, R. G.

    2003-01-01

    In order to minimize the forward contamination of Mars, spacecraft are assembled under clean-room conditions that often require several procedures to clean and sterilize components. Surface characteristics of spacecraft materials may contribute to microbial survival by protecting spores from sterilizing agents, including UV irradiation on the surface of Mars. The primary objective of this study was to evaluate the effects of surface characteristics of several spacecraft materials on the survival of Bacillus subtilis spores under simulated Martian conditions.

  5. Preliminary design of a universal Martian lander

    Science.gov (United States)

    Norman, Timothy L.; Gaskin, David E.; Adkins, Sean; Gunawan, Mary; Johnson, Raquel; Macdonnell, David; Parlock, Andrew; Sarick, John; Bodwell, Charles; Hashimoto, Kouichi

    1993-01-01

    In the next 25 years, mankind will be undertaking yet another giant leap forward in the exploration of the solar system: a manned mission to Mars. This journey will provide important information on the composition and history of both Mars and the Solar System. A manned mission will also provide the opportunity to study how humans can adapt to long term space flight conditions and the Martian environment. As part of the NASA/USRA program, nineteen West Virginia University students conducted a preliminary design of a manned Universal Martian Lander (UML). The UML's design will provide a 'universal' platform, consisting of four modules for living and laboratory experiments and a liquid-fuel propelled Manned Ascent Return Vehicle (MARV). The distinguishing feature of the UML is the 'universal' design of the modules which can be connected to form a network of laboratories and living quarters for future missions thereby reducing development and production costs. The WVU design considers descent to Mars from polar orbit, a six month surface stay, and ascent for rendezvous. The design begins with an unmanned UML landing at Elysium Mons followed by the manned UML landing nearby. During the six month surface stay, the eight modules will be assembled to form a Martian base where scientific experiments will be performed. The mission will also incorporate hydroponic plant growth into a Controlled Ecological Life Support System (CELSS) for water recycling, food production, and to counteract psychological effects of living on Mars. In situ fuel production for the MARV will be produced from gases in the Martian atmosphere. Following surface operations, the eight member crew will use the MARV to return to the Martian Transfer Vehicle (MTV) for the journey home to Earth.

  6. Preliminary design of a universal Martian lander

    Science.gov (United States)

    Norman, Timothy L.; Gaskin, David E.; Adkins, Sean; Gunawan, Mary; Johnson, Raquel; Macdonnell, David; Parlock, Andrew; Sarick, John; Bodwell, Charles; Hashimoto, Kouichi

    In the next 25 years, mankind will be undertaking yet another giant leap forward in the exploration of the solar system: a manned mission to Mars. This journey will provide important information on the composition and history of both Mars and the Solar System. A manned mission will also provide the opportunity to study how humans can adapt to long term space flight conditions and the Martian environment. As part of the NASA/USRA program, nineteen West Virginia University students conducted a preliminary design of a manned Universal Martian Lander (UML). The UML's design will provide a 'universal' platform, consisting of four modules for living and laboratory experiments and a liquid-fuel propelled Manned Ascent Return Vehicle (MARV). The distinguishing feature of the UML is the 'universal' design of the modules which can be connected to form a network of laboratories and living quarters for future missions thereby reducing development and production costs. The WVU design considers descent to Mars from polar orbit, a six month surface stay, and ascent for rendezvous. The design begins with an unmanned UML landing at Elysium Mons followed by the manned UML landing nearby. During the six month surface stay, the eight modules will be assembled to form a Martian base where scientific experiments will be performed. The mission will also incorporate hydroponic plant growth into a Controlled Ecological Life Support System (CELSS) for water recycling, food production, and to counteract psychological effects of living on Mars. In situ fuel production for the MARV will be produced from gases in the Martian atmosphere. Following surface operations, the eight member crew will use the MARV to return to the Martian Transfer Vehicle (MTV) for the journey home to Earth.

  7. Lichens as a model-system for survival of eukaryotic symbiotic associations to simulated space conditions

    Science.gov (United States)

    de Vera, J.-P.; Horneck, G.; Rettberg, P.; Ott, S.

    Lichens are symbiotic organisms associated by a fungus (mycobiont) and a a photosynthetic biont. As a consequence of the symbiotic state both the bionts are able to colonise habitats where the separate bionts would not be able to survive. The symbiosis of lichens reflects a high degree of complexity and plasticity. The combination of the different bionts enables these organisms to colonise most extreme habitats worldwide as polar regions, deserts and alpine zones. Besides the well investigated microorganisms lichens are good modelsystems to examine adaptation strategies to most extreme environmental conditions. They clearly demonstrate a high resistence to simulated space conditions concerning UV spectra (λ ≥ 160 nm) and vacuum (p = 10-5 Pa). Lichens are poikilohydric organisms. They are physiologically active if they are wet but if dry they are in the state of anabiosis. Lichens are highly resistant to simulated space conditions if they are in the dry state as has been examined in the lichen and the respective bionts of Xanthoria elegans. We performed experiments to test the resistence of wet lichens while they are physiologically active for comparison. Buellia frigida from sites on the Antarctic continent and Peltigera aphthosa colonising shady habitats in Norway have been used. The influence of different doses of UV-C on the viability of both lichen species has been studied. The analysis of the results has been done by Confocal Laser Scanning Microscopy (CLSM) using fluorescent LIVE/DEAD-substances. While B. frigida shows a very high resistence combined with a high viability to UV-C during the whole experiment the viability of the shady lichen P. aphthosadecreases immediately. The results clearly show a graded resistence in the lichen symbiosis depending on the adaptation mechanisms to the respective environmental conditions. These results will be discussed and compared with results achieved in former investigations with lichen species. The adaptation

  8. Influence of environmental conditions on the regenerative capacity and the survivability of Elodea nuttallii fragments

    Directory of Open Access Journals (Sweden)

    Markus A. Hoffmann

    2014-06-01

    Full Text Available The presented study was conducted to determine which environmental factors and conditions can affect the regenerative capacity and survivability of Elodea nuttallii [o1] and therefore the efficiency of mechanical management methods like cutting and harvesting. The influence of water temperature, light intensity and nutrient concentration in the sediment on the survivability and regenerative capacity of the invasive species E. nuttallii was determined in three laboratory and one field experiments. E. nuttallii fragments with one to four nodes were stored in aquaria under constant temperature and/or light conditions. To examine the influence of water temperature, four aquaria were kept at a constant water temperature of either 15°C or 20°C. The influence of light intensity was studied by shading the aquaria with different types of mesh. The fragments were stored at constant light intensities of 215, 161, 86 and 31 µmol photons m–2 s–1. Fragments in aquaria filled with sediment with 20 µg P2O5-P g–1 soil, 150 µg P2O5-P g–1 soil or without sediment were studied to determine the influence of the sediment. The results of the laboratory experiments showed how the mechanical management methods are most efficient during periods with low water temperatures, high turbidity or low global irradiation and nutrient poor waters. The field experiment was designed to study the influence of the nutrient compositions in the sediment on the growth and regenerative capacity of rooted E. nuttallii. E. nuttallii fragments were planted in compartments treated with PO43-- and/or NH4+-fertiliser and were trimmed after six weeks. The experiment revealed that the growth before a harvest and the growth after a harvest (regenerative capacity differ significantly, depending on the nutrient composition in the substrate. An increase of the PO43- concentration in the sediment, for example, reduced the growth of E. nuttallii before the harvest, but increased the

  9. Green tea increases the survival yield of Bifidobacteria in simulated gastrointestinal environment and during refrigerated conditions

    Directory of Open Access Journals (Sweden)

    Vodnar Dan C

    2012-06-01

    Full Text Available Abstract Background The well–known prebiotics are carbohydrates but their effects may not always be beneficial, as they can also encourage the growth of non-probiotic bacteria such as Eubacterium biforme and Clostridium perfringens. Therefore, new alternatives such as non-carbohydrate sources to stimulate the growth of probiotics are needed. The aim of this work was to evaluate (I the green tea polyphenols by HPLC-LC/MS and (II the protective effect of green tea extract on viability and stability of B. infantis ATCC 15697 and B. breve ATCC 15700 microencapsulated in chitosan coated alginate microcapsules during exposure to simulated gastrointestinal conditions and refrigerated storage. Results The major compound identified by HPLC-LC/MS in green tea was epigallocatechin gallate followed by caffeine and epigallocatechin. The survival yield of probiotic bacteria in microcapsules with 10% GT during storage at 4°C, demonstrated significantly (P B.infantis and B. breve with 5% and 10% GT showed a significantly (P  Conclusions The results of this study suggest that green tea coencapsulated with B. infantis or B. breve exert a protective effect of bacteria during exposure to gastrointestinal conditions and refrigerated storage. For a health perspective, the results confirm the growing interest probiotic bacteria and the perceived benefit of increasing their numbers in the gastrointestinal tract by microencapsulation.

  10. Utility of tree crown condition indicators to predict tree survival using remeasured Forest Inventory and Analysis data

    Science.gov (United States)

    Randall S. Morin; Jim Steinman; KaDonna C. Randolph

    2012-01-01

    The condition of tree crowns is an important indicator of tree and forest health. Crown conditions have been evaluated during surveys of Forest Inventory and Analysis (FIA) Phase 3 (P3) plots since 1999. In this study, remeasured data from 39,357 trees in the northern United States were used to assess the probability of survival among various tree species using the...

  11. Growth and Survival of Perchlorate-Reducing Bacteria in Media Containing Elevated Perchlorate Concentrations and UV-C Conditions

    Science.gov (United States)

    Bywaters, K. F.; Mckay, C. P.; Quinn, R. C.

    2017-01-01

    Introduction: The identification of perchlorate (ClO4(-)) on Mars has led to the possibility that complete redox couples are available for microbial metabolism in contemporary surface environments. Perchlorate-reducing bacteria (PRB) utilize ClO4(-) and chlorate (ClO3(-)) as terminal electron acceptors due to the high reduction potential. Additionally, ClO4(-) salts have been suggested as a possible source of brines on Mars and spectral evidence indicates that the hydration of ClO4(-) salts in the regolith of Martian is linked to the surface recurring slope lineae (RSL). For these reasons PRB may serve as analog organisms for possible life on Mars. However, there is very little information on the viability of PRB in aqueous environments that contain high levels of perchlorate Microorganisms on or near the surface of Mars, such as in the RSL, would potentially be exposed to high-salinity and high ultraviolet radiation environments. Under these extreme conditions, microorganisms must possess mechanisms for maintaining continued high genome fidelity. To assess possible microbial viability in contemporary Mars analog environments we are investigating the tolerance of two PRB strains in aqueous conditions under high UV-C conditions and high ClO4(-) concentrations.

  12. Floral resource limitation severely reduces butterfly survival, condition and flight activity in simplified agricultural landscapes.

    Science.gov (United States)

    Lebeau, Julie; Wesselingh, Renate A; Van Dyck, Hans

    2016-02-01

    Agricultural intensification has a strong negative impact on farmland biodiversity (including flower-visiting insects), but understanding the mechanisms involved in this requires experimental work. We document the impact of nectar limitation on the performance of a flower-visiting insect, the meadow brown butterfly Maniola jurtina. We conducted two types of experiments: a field experiment in agricultural landscapes with grasslands of different management intensity and an experiment in outdoor flight cages in which the nectar supply was simulated. For the field experiment, we introduced an array of nectar resources in intensively managed, nectar-poor meadows and in extensively managed, flower-rich grasslands and counted flower visitors. Despite higher butterfly abundance in the extensive meadows, our introduced nectar sources were more frequently visited in intensive meadows, indicating the lack of floral resources. The 48-h confinement under nectar-poor conditions in the flight cages had a strong negative effect on body condition, flight activity and lifetime survival compared to butterflies under nectar-rich conditions. Female lifespan was reduced by 22% and male lifespan even by 43%. Agricultural landscapes that provide limited amounts of floral nectar, and no high-quality, preferred nectar sources relative to the needs of the flower-visiting species, may create ecological sinks. Regards an insect's performance, the simple presence of nectar is not necessarily functionally adequate. The effectiveness of agri-environmental schemes for flower-visiting insects (e.g. flower strips) could be improved based on ecological and evolutionary insights on the effects of specific nectar quantities and qualities.

  13. SURVIVAL OF MICROORGANISMS FROM MODERN PROBIOTICS IN MODEL CONDITIONS OF THE INTESTINE

    Directory of Open Access Journals (Sweden)

    Kabluchko TV

    2017-03-01

    .3, later after centrifugation and washing, they were incubated for 3 hours in intestinal model environment (bile salts 3% pancreatin 0.1%, pH 7.0. Inoculation was performed before incubation, after incubation in the gastric medium and after incubation in intestinal medium. We used the medium corresponding to the studied genus of bacteria - MRS-environment for lactobacilli, bifidum for Bifidobacterium, sabouraud medium for the isolation of yeasts and fungi and endo agar for the isolation of Enterobacteriaceae. We assessed the quantity of CFU before and after impact. Results and discussion. After incubation in a simulated gastric environment, bacteria of the type Lactobacillus and Bifidobacterium did not survive and were not defined. Only Bacillus coagulans and Saccharomyces boulardii were resistant. These microorganisms grew after incubation in the same amount as before incubation - 105-6 and 107-8 CFU respectively. Bacillus clausii also survived in these conditions, but to a lesser extent: initially - 107 CFU, after incubation - 105 CFU. After staying in model environment of the duodenum Bacillus coagulans and Saccharomyces boulardii were still fully viable, and the number of germinating Bacillus clausii bacteria decreased by an order - up to 104 CFU. Conclusion. The probiotics containing Bacillus coagulans and Saccharomyces boulardii showed complete resistance to the impact of the model environment of the stomach and duodenum, Bacillus clausii was partially resistant. It leads to conclusion that probiotic drugs containing lactobacilli and bifidobacteria, cannot withstand the aggressive environmental influence of the stomach and duodenum and become inactivated under their influence. Probiotic drugs Enterol containing yeast Saccharomyces boulardii, and Laktovit Forte containing the spore-forming bacterium Bacillus coagulans are completely resistant to the action of the model environment of the stomach and duodenum.

  14. Survival of akinetes (resting-state cells of cyanobacteria) in low earth orbit and simulated extraterrestrial conditions.

    Science.gov (United States)

    Olsson-Francis, Karen; de la Torre, Rosa; Towner, Martin C; Cockell, Charles S

    2009-12-01

    Cyanobacteria are photosynthetic organisms that have been considered for space applications, such as oxygen production in bioregenerative life support systems, and can be used as a model organism for understanding microbial survival in space. Akinetes are resting-state cells of cyanobacteria that are produced by certain genera of heterocystous cyanobacteria to survive extreme environmental conditions. Although they are similar in nature to endospores, there have been no investigations into the survival of akinetes in extraterrestrial environments. The aim of this work was to examine the survival of akinetes from Anabaena cylindrica in simulated extraterrestrial conditions and in Low Earth Orbit (LEO). Akinetes were dried onto limestone rocks and sent into LEO for 10 days on the ESA Biopan VI. In ground-based experiments, the rocks were exposed to periods of desiccation, vacuum (0.7×10(-3) kPa), temperature extremes (-80 to 80°C), Mars conditions (-27°C, 0.8 kPa, CO(2)) and UV radiation (325-400 nm). A proportion of the akinete population was able to survive a period of 10 days in LEO and 28 days in Mars simulated conditions, when the rocks were not subjected to UV radiation. Furthermore, the akinetes were able to survive 28 days of exposure to desiccation and low temperature with high viability remaining. Yet long periods of vacuum and high temperature were lethal to the akinetes. This work shows that akinetes are extreme-tolerating states of cyanobacteria that have a practical use in space applications and yield new insight into the survival of microbial resting-state cells in space conditions.

  15. Adult survival, apparent lamb survival, and body condition of desert bighorn sheep in relation to habitat and precipitation on the Kofa National Wildlife Refuge, Arizona

    Science.gov (United States)

    Overstreet, Matthew; Caldwell, Colleen A.; Cain, James W.

    2014-01-01

    The decline of desert bighorn sheep on the Kofa National Wildlife Refuge (KNWR) beginning in 2003 stimulated efforts to determine the factors limiting survival and recruitment. We 1) determined pregnancy rates, body fat, and estimated survival rates of adults and lambs; 2) investigated the relationship between precipitation, forage conditions, previous year’s reproductive success, and adult body condition; 3) assessed the relative influence of body condition of adult females, precipitation, and forage characteristics on apparent survival of lambs; and 4) determined the prevalence of disease. To assess the influence of potential limiting factors on female desert bighorn sheep on the KNWR, we modeled percent body fat of adult females as a function of previous year’s reproductive effort, age class, and forage conditions (i.e., seasonal NDVI and seasonal precipitation). In addition, we assessed the relative influence of the body condition of adult females, precipitation, and forage conditions (NDVI) on length of time a lamb was observed at heel.Adult female survival was high in both 2009 (0.90 [SE = 0.05]) and 2010 (0.96 [SE = 0.03]). Apparent lamb survival to 6 months of age was 0.23 (SE = 0.05) during 2009-2010 and 0.21 (SE = 0.05) during 2010-2011 lambing seasons. Mean body fat for adult females was 12.03% (SE = 0.479) in 2009-2010 and 11.11% (SE= 0.486) in 2010-2011 and was not significantly different between years. Pregnancy rate was 100% in 2009 and 97.5% in 2010.Models containing the previous year’s reproductive effort, spring NDVI and previous year’s reproductive effort and spring precipitation best approximated data on percent body fat in adult females in 2009-2010. In 2010-2011, the two highest-ranking models included the previous year’s reproductive effort and winter NDVI and previous year’s reproductive effort, and winter and spring NDVI. None of the models assessing the influence of maternal body fat, precipitation, or forage conditions were

  16. Predicting long-term risk for relationship dissolution using nonparametric conditional survival trees.

    Science.gov (United States)

    Kliem, Sören; Weusthoff, Sarah; Hahlweg, Kurt; Baucom, Katherine J W; Baucom, Brian R

    2015-12-01

    Identifying risk factors for divorce or separation is an important step in the prevention of negative individual outcomes and societal costs associated with relationship dissolution. Programs that aim to prevent relationship distress and dissolution typically focus on changing processes that occur during couple conflict, although the predictive ability of conflict-specific variables has not been examined in the context of other factors related to relationship dissolution. The authors examine whether emotional responding and communication during couple conflict predict relationship dissolution after controlling for overall relationship quality and individual well-being. Using nonparametric conditional survival trees, the study at hand simultaneously examined the predictive abilities of physiological (systolic and diastolic blood pressure, heart rate, cortisol) and behavioral (fundamental frequency; f0) indices of emotional responding, as well as observationally coded positive and negative communication behavior, on long-term relationship stability after controlling for relationship satisfaction and symptoms of depression. One hundred thirty-six spouses were assessed after participating in a randomized clinical trial of a relationship distress prevention program as well as 11 years thereafter; 32.5% of the couples' relationships had dissolved by follow up. For men, the only significant predictor of relationship dissolution was cortisol change score (p = .012). For women, only f0 range was a significant predictor of relationship dissolution (p = .034). These findings highlight the importance of emotional responding during couple conflict for long-term relationship stability. (c) 2015 APA, all rights reserved).

  17. Effects of environmental conditions on growth and survival of Salmonella in pasteurized whole egg

    DEFF Research Database (Denmark)

    Jakociune, Dziuginta; Bisgaard, Magne; Hervé, Gaëlle

    2014-01-01

    This study investigated the influence of three parameters (time, temperature and NaCl concentration) on survival and four parameters (temperature, NaCl and lysozyme concentrations and pH) on growth of Salmonella enterica serovar Enteritidis (S. Enteritidis) in pasteurized whole egg (PWE). Doehlert...... times between 30 and 210s and a model for prediction of growth rate of S. Enteritidis in PWE in the temperature range of 1-25°C, NaCl concentration of 0-12%, pH between 5 and 9, and lysozyme concentrations of 107-1007 U/mg proteins were developed. The maximum reduction condition was 58°C, 0% of Na......Cl at a fixed heating time of 120s, while maximum growth rate was estimated at 25°C and 0% of NaCl. pH and lysozyme concentration were shown not to influence growth performance significantly in the range of values studied. Results inform industry of the optimal pasteurization and storage parameters for liquid...

  18. Environmental conditions and prey-switching by a seabird predator impact juvenile salmon survival

    Science.gov (United States)

    Wells, Brian K.; Santora, Jarrod A.; Henderson, Mark J.; Warzybok, Pete; Jahncke, Jaime; Bradley, Russell W.; Huff, David D.; Schroeder, Isaac D.; Nelson, Peter; Field, John C.; Ainley, David G.

    2017-01-01

    Due to spatio-temporal variability of lower trophic-level productivity along the California Current Ecosystem (CCE), predators must be capable of switching prey or foraging areas in response to changes in environmental conditions and available forage. The Gulf of the Farallones in central California represents a biodiversity hotspot and contains the largest common murre (Uria aalge) colonies along the CCE. During spring, one of the West Coast's most important Chinook salmon (Oncorhynchus tshawytscha) populations out-migrates into the Gulf of the Farallones. We quantify the effect of predation on juvenile Chinook salmon associated with ecosystem-level variability by integrating long-term time series of environmental conditions (upwelling, river discharge), forage species abundance within central CCE, and population size, at-sea distribution, and diet of the common murre. Our results demonstrate common murres typically forage in the vicinity of their offshore breeding sites, but in years in which their primary prey, pelagic young-of-year rockfish (Sebastesspp.), are less available they forage for adult northern anchovies (Engraulis mordax) nearshore. Incidentally, while foraging inshore, common murre consumption of out-migrating juvenile Chinook salmon, which are collocated with northern anchovy, increases and population survival of the salmon is significantly reduced. Results support earlier findings that show timing and strength of upwelling, and the resultant forage fish assemblage, is related to Chinook salmon recruitment variability in the CCE, but we extend those results by demonstrating the significance of top-down impacts associated with these bottom-up dynamics. Our results demonstrate the complexity of ecosystem interactions and impacts between higher trophic-level predators and their prey, complexities necessary to quantify in order to parameterize ecosystem models and evaluate likely outcomes of ecosystem management options.

  19. Environmental conditions and prey-switching by a seabird predator impact juvenile salmon survival

    Science.gov (United States)

    Wells, Brian K.; Santora, Jarrod A.; Henderson, Mark J.; Warzybok, Pete; Jahncke, Jaime; Bradley, Russell W.; Huff, David D.; Schroeder, Isaac D.; Nelson, Peter; Field, John C.; Ainley, David G.

    2017-10-01

    Due to spatio-temporal variability of lower trophic-level productivity along the California Current Ecosystem (CCE), predators must be capable of switching prey or foraging areas in response to changes in environmental conditions and available forage. The Gulf of the Farallones in central California represents a biodiversity hotspot and contains the largest common murre (Uria aalge) colonies along the CCE. During spring, one of the West Coast's most important Chinook salmon (Oncorhynchus tshawytscha) populations out-migrates into the Gulf of the Farallones. We quantify the effect of predation on juvenile Chinook salmon associated with ecosystem-level variability by integrating long-term time series of environmental conditions (upwelling, river discharge), forage species abundance within central CCE, and population size, at-sea distribution, and diet of the common murre. Our results demonstrate common murres typically forage in the vicinity of their offshore breeding sites, but in years in which their primary prey, pelagic young-of-year rockfish (Sebastes spp.), are less available they forage for adult northern anchovies (Engraulis mordax) nearshore. Incidentally, while foraging inshore, common murre consumption of out-migrating juvenile Chinook salmon, which are collocated with northern anchovy, increases and population survival of the salmon is significantly reduced. Results support earlier findings that show timing and strength of upwelling, and the resultant forage fish assemblage, is related to Chinook salmon recruitment variability in the CCE, but we extend those results by demonstrating the significance of top-down impacts associated with these bottom-up dynamics. Our results demonstrate the complexity of ecosystem interactions and impacts between higher trophic-level predators and their prey, complexities necessary to quantify in order to parameterize ecosystem models and evaluate likely outcomes of ecosystem management options.

  20. The responses of an anaerobic microorganism, Yersinia intermedia MASE-LG-1 to individual and combined simulated Martian stresses.

    Directory of Open Access Journals (Sweden)

    Kristina Beblo-Vranesevic

    Full Text Available The limits of life of aerobic microorganisms are well understood, but the responses of anaerobic microorganisms to individual and combined extreme stressors are less well known. Motivated by an interest in understanding the survivability of anaerobic microorganisms under Martian conditions, we investigated the responses of a new isolate, Yersinia intermedia MASE-LG-1 to individual and combined stresses associated with the Martian surface. This organism belongs to an adaptable and persistent genus of anaerobic microorganisms found in many environments worldwide. The effects of desiccation, low pressure, ionizing radiation, varying temperature, osmotic pressure, and oxidizing chemical compounds were investigated. The strain showed a high tolerance to desiccation, with a decline of survivability by four orders of magnitude during a storage time of 85 days. Exposure to X-rays resulted in dose-dependent inactivation for exposure up to 600 Gy while applied doses above 750 Gy led to complete inactivation. The effects of the combination of desiccation and irradiation were additive and the survivability was influenced by the order in which they were imposed. Ionizing irradiation and subsequent desiccation was more deleterious than vice versa. By contrast, the presence of perchlorates was not found to significantly affect the survival of the Yersinia strain after ionizing radiation. These data show that the organism has the capacity to survive and grow in physical and chemical stresses, imposed individually or in combination that are associated with Martian environment. Eventually it lost its viability showing that many of the most adaptable anaerobic organisms on Earth would be killed on Mars today.

  1. Fecundity, survival, and growth of the seahorse Hippocampus ingens (Pisces: Syngnathidae under semi-controlled conditions

    Directory of Open Access Journals (Sweden)

    A.A Ortega-Salas

    2006-12-01

    Full Text Available Estudiamos la fecundidad, supervivencia, y crecimiento del caballito de mar, Hippocampus ingens en condiciones semi-controladas. Tres machos reproductores silvestres de 14.8, 24.5 y 32.0 g produjeron 1 598, 1 703 y 1 658 jóvenes. La densidad utilizada fue de 12 jóvenes por acuario de 60 l. Se agruparon en 1, 12 y 20 días de nacidos por acuario. La supervivencia fue de 78.5, 38.1 y 41.0 % en 35 días. Se les alimentó con una mezcla de rotíferos B. plicatilis y nauplios de Artemia para después transferirlos a estanques de 100 000 l a una densidad de 50/1 000 l, donde se les alimentó con Artemia adulta durante 60 días más. Crecieron de un promedio de 0.7, 1.5, y 2.7 a 4.5, 5.4 6.7 cm, respectivamente, en 95 días. La temperatura del agua marina utilizada varió de 17 a 23 ºC.We studied fecundity, survival, and growth of the seahorse Hippocampus ingens under semi-controlled conditions. Three wild brood stock mature males of 14.8, 24.5, and 32.0 g released 1 598, 1 703, and 1 658 juveniles. Juvenile stocking densities of 12 were settled in 60-l aquariums in groups of 1, 12, and 20 days old organisms. The rate of survival was 21.5, 61.9, and 59.0 %, respectively, in 35 days. Juveniles were fed a mix diet of rotifers B. plicatilis and Artemia nauplii, then they were transferred to a cement tank of 100 000 l at a density of 50/1 000 l and fed with live adult Artemia for 60 days more. They grew from an average of 0.7, 1.5, and 2.7 to 4.5, 5.4, and 6.7 cm, respectively, in 95 days. The seawater temperature varied from 17 to 23 ºC. Rev. Biol. Trop. 54 (4: 1099-1102. Epub 2006 Dec. 15.

  2. Martian Atmospheric Pressure Static Charge Elimination Tool

    Science.gov (United States)

    Johansen, Michael R.

    2014-01-01

    A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

  3. Evaluation of the Survivability of Microorganisms Deposited on Filtering Respiratory Protective Devices under Varying Conditions of Humidity.

    Science.gov (United States)

    Majchrzycka, Katarzyna; Okrasa, Małgorzata; Skóra, Justyna; Gutarowska, Beata

    2016-01-04

    Bioaerosols are common biological factors in work environments, which require routine use of filtering respiratory protective devices (FRPDs). Currently, no studies link humidity changes in the filter materials of such devices, during use, with microorganism survivability. Our aim was to determine the microclimate inside FRPDs, by simulating breathing, and to evaluate microorganism survivability under varying humidity conditions. Breathing was simulated using commercial filtering facepiece respirators in a model system. Polypropylene melt-blown nonwoven fabrics with moisture contents of 40%, 80%, and 200%, were used for assessment of microorganisms survivability. A modified AATCC 100-2004 method was used to measure the survivability of ATCC and NCAIM microorganisms: Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albicans and Aspergillus niger. During simulation relative humidity under the facepiece increased after 7 min of usage to 84%-92% and temperature increased to 29-30 °C. S. aureus survived the best on filter materials with 40%-200% moisture content. A decrease in survivability was observed for E. coli and C. albicans when mass humidity decreased. We found that B. subtilis and A. niger proliferated for 48-72 h of incubation and then died regardless of the moisture content. In conclusion, our tests showed that the survivability of microorganisms on filter materials depends on the amount of accumulated moisture and microorganism type.

  4. Evaluation of the Survivability of Microorganisms Deposited on Filtering Respiratory Protective Devices under Varying Conditions of Humidity

    Directory of Open Access Journals (Sweden)

    Katarzyna Majchrzycka

    2016-01-01

    Full Text Available Bioaerosols are common biological factors in work environments, which require routine use of filtering respiratory protective devices (FRPDs. Currently, no studies link humidity changes in the filter materials of such devices, during use, with microorganism survivability. Our aim was to determine the microclimate inside FRPDs, by simulating breathing, and to evaluate microorganism survivability under varying humidity conditions. Breathing was simulated using commercial filtering facepiece respirators in a model system. Polypropylene melt-blown nonwoven fabrics with moisture contents of 40%, 80%, and 200%, were used for assessment of microorganisms survivability. A modified AATCC 100-2004 method was used to measure the survivability of ATCC and NCAIM microorganisms: Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albicans and Aspergillus niger. During simulation relative humidity under the facepiece increased after 7 min of usage to 84%–92% and temperature increased to 29–30 °C. S. aureus survived the best on filter materials with 40%–200% moisture content. A decrease in survivability was observed for E. coli and C. albicans when mass humidity decreased. We found that B. subtilis and A. niger proliferated for 48–72 h of incubation and then died regardless of the moisture content. In conclusion, our tests showed that the survivability of microorganisms on filter materials depends on the amount of accumulated moisture and microorganism type.

  5. Evaluation of the Survivability of Microorganisms Deposited on Filtering Respiratory Protective Devices under Varying Conditions of Humidity

    Science.gov (United States)

    Majchrzycka, Katarzyna; Okrasa, Małgorzata; Skóra, Justyna; Gutarowska, Beata

    2016-01-01

    Bioaerosols are common biological factors in work environments, which require routine use of filtering respiratory protective devices (FRPDs). Currently, no studies link humidity changes in the filter materials of such devices, during use, with microorganism survivability. Our aim was to determine the microclimate inside FRPDs, by simulating breathing, and to evaluate microorganism survivability under varying humidity conditions. Breathing was simulated using commercial filtering facepiece respirators in a model system. Polypropylene melt-blown nonwoven fabrics with moisture contents of 40%, 80%, and 200%, were used for assessment of microorganisms survivability. A modified AATCC 100-2004 method was used to measure the survivability of ATCC and NCAIM microorganisms: Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albicans and Aspergillus niger. During simulation relative humidity under the facepiece increased after 7 min of usage to 84%–92% and temperature increased to 29–30 °C. S. aureus survived the best on filter materials with 40%–200% moisture content. A decrease in survivability was observed for E. coli and C. albicans when mass humidity decreased. We found that B. subtilis and A. niger proliferated for 48–72 h of incubation and then died regardless of the moisture content. In conclusion, our tests showed that the survivability of microorganisms on filter materials depends on the amount of accumulated moisture and microorganism type. PMID:26742049

  6. Survival and weight change among adult individuals of Periplaneta americana (Linnaeus, 1758 (Blattaria, Blattidae subject to various stress conditions

    Directory of Open Access Journals (Sweden)

    Jucelio Peter Duarte

    2015-03-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2015v28n2p103 Periplaneta americana is a species of great importance to public health, since it can act as a vector of many pathogens and it reaches large populations in urban environments. This is probably due to its ability to resist starvation and desiccation. This study aimed to evaluate the effects of absence of water and food on survival and weight change among adult P. americana individuals and check whether the initial weight of individuals influences on their survival. Four groups having twenty P. americana couples were formed and subject to: I no water or food; II no food; III no water; and IV control group. Insects were isolated according to the groups, which were weighed at the beginning and end of the stress conditions. They remained under these conditions until all individuals in each test group were dead. Stress conditions caused reduction in survival time when compared to the control group. Adults with higher body mass survived longer when deprived only of food, while among those lacking water, weight had no influence on survival. Total weight loss was greater among individuals deprived of water than those deprived only of food.

  7. Estimates of conditional survival in gastric cancer reveal a reduction of racial disparities with long-term follow-up.

    Science.gov (United States)

    Luyimbazi, David; Nelson, Rebecca A; Choi, Audrey H; Li, Lily; Chao, Joseph; Sun, Virginia; Hamner, John B; Kim, Joseph

    2015-02-01

    In prior analyses, conditional survival (CS) estimates for gastric cancer have weighed clinical and pathologic factors to predict prognosis at time intervals after surgery. Since racial disparities in gastric cancer outcomes were not considered, our objective was to determine whether race influences CS estimates. Data from the Surveillance, Epidemiology, and End Results cancer registry were used to identify gastric adenocarcinoma patients who underwent curative surgical intervention between 1988 and 2005. Five-year relative conditional survival (RCS) was computed for patients who survived at least 1 to 5 years after surgery. RCS was calculated by assessing observed and expected survival in an age- and race-matched standard population. Results were compared across time and racial groups (white, black, and Asian) using z test statistics. Of 14,067 patients, 63.8 % were white, 15.5 % black, and 20.7 % Asian. Racial disparities among groups were observed with improved survival of Asians at time point zero and improved RCS at 1 year. At 5 years following curative surgery, each racial group had increased RCS and the greatest magnitude of relative increase was observed in white and black patients (121 and 118 %, respectively). Comparison of RCS at the 5-year time point revealed a reduction of racial disparities in survival among the three groups. Our investigation shows that racial disparities in gastric cancer outcomes are pronounced at the time of curative surgery but diminish after years of survival, thus suggesting race has less influence over outcomes the longer patients survive. The reasons for reduction of racial disparities remain unclear and warrant future study.

  8. Conditional Survival and the Choice of Conditioning Set for Patients With Colon Cancer: An Analysis of NSABP Trials C-03 Through C-07

    Science.gov (United States)

    Zamboni, Beth A.; Yothers, Greg; Choi, Mehee; Fuller, Clifton D.; Dignam, James J.; Raich, Peter C.; Thomas, Charles R.; O'Connell, Michael J.; Wolmark, Norman; Wang, Samuel J.

    2010-01-01

    Purpose Colon cancer overall survival (OS) is usually computed from the time of diagnosis. Survival gives the initial prognosis but does not reflect how prognosis changes with changing hazard rates over time. Conditional survival (probability of surviving y additional years given they have survived x years [CS or OS|OS]) is an alternative measure that accounts for elapsed time since diagnosis, providing more relevant prognostic information. We extend the concept of CS to condition on the set of patients alive, recurrence-free, and second primary cancer-free (disease-free survival [OS|DFS]). Patients and Methods Using data from National Surgical Adjuvant Breast and Bowel Project trials C-03 through C-07, 5-year OS|DFS was calculated on patients who were disease free up to 5 years after diagnosis, stratified by age, stage, nodal status, and performance status (PS). Results For stage II, OS|DFS improved from 87% to 92% at 5 years. For stage III, OS|DFS improved from 69% to 88%. Patients younger than 50 years showed OS|DFS improvement from 79% to 95%; those older than 70 years showed no sustained increase in OS|DFS. Node-negative patients with ≥ 12 nodes resected showed little change (89% to 94%); those with more than four positive nodes showed an improvement (57% to 86%). Patients with a PS of 0 or 1 demonstrated a small improvement; those with a PS of 2 did not (64% to 58%). Conclusion Prognosis improves over time for almost all groups of patients with colon cancer, especially those with positive nodes. OS|DFS is a more relevant measure of prognosis for those who have already survived disease free a period of time after diagnosis. PMID:20406942

  9. Survival of lichens and bacteria exposed to outer space conditions - Results of the Lithopanspermia experiments

    Science.gov (United States)

    de la Torre, Rosa; Sancho, Leopoldo G.; Horneck, Gerda; Ríos, Asunción de los; Wierzchos, Jacek; Olsson-Francis, Karen; Cockell, Charles S.; Rettberg, Petra; Berger, Thomas; de Vera, Jean-Pierre P.; Ott, Sieglinde; Frías, Jesus Martinez; Melendi, Pablo Gonzalez; Lucas, Maria Mercedes; Reina, Manuel; Pintado, Ana; Demets, René

    2010-08-01

    In the space experiments Lithopanspermia, experimental support was provided to the likelihood of the lithopanspermia concept that considers a viable transport of microorganisms between the terrestrial planets by means of meteorites. The rock colonising lichens Rhizocarpon geographicum and Xanthoria elegans, the vagrant lichen Aspicilia fruticulosa, and endolithic and endoevaporitic communities of cyanobacteria and bacteria with their natural rock substrate were exposed to space for 10 days onboard the Biopan facility of the European Space Agency (ESA). Biopan was closed during launch and re-entry. In addition, in the Stone facility, one sample of R. geographicum on its natural granitic substrate was attached at the outer surface of the re-entry capsule close to the stagnation point, only protected by a thin cover of glass textolite. Post-flight analysis, which included determination of the photosynthetic activity, LIVE/DEAD staining, and germination capacity of the ascospores, demonstrated that all three lichen were quite resistant to outer space conditions, which include the full spectrum of solar extraterrestrial electromagnetic radiation or selected wavelength ranges. This high resistance of the lichens to space appears to be due to their symbiotic nature and protection by their upper pigmented layer, the cortex. In contrast, the rock- or halite-inhabiting bacteria were severely damaged by the same exposure. After atmospheric re-entry, the granite of the Stone sample was transformed into a glassy, nearly homogenous material, with several friction striae. None of the lichen cells survived this re-entry process. The data suggest that lichens are suitable candidates for testing the concept of lithopanspermia, because they are extremely resistant to the harsh environment of outer space. The more critical event is the atmospheric re-entry after being captured by a planet. Experiments simulating the re-entry process of a microbe-carrying meteoroid did not show any

  10. Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates of Bacteria on Mars Landers

    Science.gov (United States)

    Schuerger, Andrew C.; Kern, Roger G.

    2004-01-01

    In order to minimize the forward contamination of Mars, spacecraft are assembled under cleanroom conditions that require several procedures to clean and sterilize components. Surface characteristics of spacecraft materials may contribute to microbial survival on the surface of Mars by protecting spores from sterilizing agents, including UV irradiation. The primary objective of this study was to evaluate the effects of surface characteristics of several spacecraft materials on the survival of Bacillus subtilis spores under simulated Martian conditions.

  11. Bacillus subtilis spore survival and expression of germination-induced bioluminescence after prolonged incubation under simulated Mars atmospheric pressure and composition: implications for planetary protection and lithopanspermia

    Science.gov (United States)

    Nicholson, Wayne L.; Schuerger, Andrew C.

    2005-01-01

    Bacterial endospores in the genus Bacillus are considered good models for studying interplanetary transfer of microbes by natural or human processes. Although spore survival during transfer itself has been the subject of considerable study, the fate of spores in extraterrestrial environments has received less attention. In this report we subjected spores of a strain of Bacillus subtilis, containing luciferase resulting from expression of an sspB-luxAB gene fusion, to simulated martian atmospheric pressure (7-18 mbar) and composition (100% CO(2)) for up to 19 days in a Mars simulation chamber. We report here that survival was similar between spores exposed to Earth conditions and spores exposed up to 19 days to simulated martian conditions. However, germination-induced bioluminescence was lower in spores exposed to simulated martian atmosphere, which suggests sublethal impairment of some endogenous spore germination processes.

  12. Electrical Activity in Martian Dust Storms

    Science.gov (United States)

    Majid, W.; Arabshahi, S.; Kocz, J.

    2016-12-01

    Dust storms on Mars are predicted to be capable of producing electrostatic fields and discharges, even larger than those in dust storms on Earth. Such electrical activity poses serious risks to any Human exploration of the planet and the lack of sufficient data to characterize any such activity has been identified by NASA's MEPAG as a key human safety knowledge gap. There are three key elements in the characterization of Martian electrostatic discharges: dependence on Martian environmental conditions, frequency of occurrence, and the strength of the generated electric fields. We will describe a recently deployed detection engine using NASA's Deep Space Network (DSN) to carry out a long term monitoring campaign to search for and characterize the entire Mars hemisphere for powerful discharges during routine tracking of spacecraft at Mars on an entirely non-interfering basis. The resulting knowledge of Mars electrical activity would allow NASA to plan risk mitigation measures to ensure human safety during Mars exploration. In addition, these measurements will also allow us to place limits on presence of oxidants such as H2O2 that may be produced by such discharges, providing another measurement point for models describing Martian atmospheric chemistry and habitability. Because of the continuous Mars telecommunication needs of NASA's Mars-based assets, the DSN is the only instrument in the world that combines long term, high cadence, observing opportunities with large sensitive telescopes, making it a unique asset worldwide in searching for and characterizing electrostatic activity at Mars from the ground.

  13. Iron snow in the Martian core?

    Science.gov (United States)

    Davies, Christopher J.; Pommier, Anne

    2018-01-01

    The decline of Mars' global magnetic field some 3.8-4.1 billion years ago is thought to reflect the demise of the dynamo that operated in its liquid core. The dynamo was probably powered by planetary cooling and so its termination is intimately tied to the thermochemical evolution and present-day physical state of the Martian core. Bottom-up growth of a solid inner core, the crystallization regime for Earth's core, has been found to produce a long-lived dynamo leading to the suggestion that the Martian core remains entirely liquid to this day. Motivated by the experimentally-determined increase in the Fe-S liquidus temperature with decreasing pressure at Martian core conditions, we investigate whether Mars' core could crystallize from the top down. We focus on the "iron snow" regime, where newly-formed solid consists of pure Fe and is therefore heavier than the liquid. We derive global energy and entropy equations that describe the long-timescale thermal and magnetic history of the core from a general theory for two-phase, two-component liquid mixtures, assuming that the snow zone is in phase equilibrium and that all solid falls out of the layer and remelts at each timestep. Formation of snow zones occurs for a wide range of interior and thermal properties and depends critically on the initial sulfur concentration, ξ0. Release of gravitational energy and latent heat during growth of the snow zone do not generate sufficient entropy to restart the dynamo unless the snow zone occupies at least 400 km of the core. Snow zones can be 1.5-2 Gyrs old, though thermal stratification of the uppermost core, not included in our model, likely delays onset. Models that match the available magnetic and geodetic constraints have ξ0 ≈ 10% and snow zones that occupy approximately the top 100 km of the present-day Martian core.

  14. Investigating the effects of simulated martian ultraviolet radiation on Halococcus dombrowskii and other extremely halophilic archaebacteria.

    Science.gov (United States)

    Fendrihan, Sergiu; Bérces, Attila; Lammer, Helmut; Musso, Maurizio; Rontó, György; Polacsek, Tatjana K; Holzinger, Anita; Kolb, Christoph; Stan-Lotter, Helga

    2009-01-01

    The isolation of viable extremely halophilic archaea from 250-million-year-old rock salt suggests the possibility of their long-term survival under desiccation. Since halite has been found on Mars and in meteorites, haloarchaeal survival of martian surface conditions is being explored. Halococcus dombrowskii H4 DSM 14522(T) was exposed to UV doses over a wavelength range of 200-400 nm to simulate martian UV flux. Cells embedded in a thin layer of laboratory-grown halite were found to accumulate preferentially within fluid inclusions. Survival was assessed by staining with the LIVE/DEAD kit dyes, determining colony-forming units, and using growth tests. Halite-embedded cells showed no loss of viability after exposure to about 21 kJ/m(2), and they resumed growth in liquid medium with lag phases of 12 days or more after exposure up to 148 kJ/m(2). The estimated D(37) (dose of 37 % survival) for Hcc. dombrowskii was > or = 400 kJ/m(2). However, exposure of cells to UV flux while in liquid culture reduced D(37) by 2 orders of magnitude (to about 1 kJ/m(2)); similar results were obtained with Halobacterium salinarum NRC-1 and Haloarcula japonica. The absorption of incoming light of shorter wavelength by color centers resulting from defects in the halite crystal structure likely contributed to these results. Under natural conditions, haloarchaeal cells become embedded in salt upon evaporation; therefore, dispersal of potential microscopic life within small crystals, perhaps in dust, on the surface of Mars could resist damage by UV radiation.

  15. Conditional survival for longer-term survivors from 2000-2004 using population-based cancer registry data in Osaka, Japan.

    Science.gov (United States)

    Ito, Yuri; Nakayama, Tomio; Miyashiro, Isao; Ioka, Akiko; Tsukuma, Hideaki

    2013-06-22

    We usually report five-year survival from population-based cancer registries in Japan; however these survival estimates may be pessimistic for cancer survivors, because many patients with unfavourable prognosis die shortly after diagnosis. Conditional survival can provide relevant information for cancer survivors, their family and oncologists. We used the period approach to estimate the latest 10-year survival of 38,439 patients with stomach, colorectal, lung, breast and prostate cancer diagnosed between 1990 and 2004 and followed-up from 2000-04 in Osaka, Japan. Conditional survival is an estimate, with the pre-condition of having already survived a certain length of time. Conditional five-year relative survival of one to five years after diagnosis was calculated by site, age and stage for survivors under the age of 70. Five-year relative survival for stomach cancer was 60%. Conditional five-year relative survival was 77% one year after diagnosis and 97% five years after diagnosis. This means that 97% of patients who survive five years after diagnosis can survive a further five years. Conditional five-year relative survival improved successively with each additional year that patients lived after diagnosis for stomach, colorectal and lung cancer. These figures for breast and prostate cancer were stable at high survival. Liver cancer did not show an increase in conditional five-year survival. Conditional five-year survival is a relevant figure for long-term cancer survivors in Japan. It is important for population-based cancer registries to provide figures which cancer patients and oncologists really need.

  16. Storage condition of mulberry branches (Morus sp. in the survival, development and production of Bombyx mori L.

    Directory of Open Access Journals (Sweden)

    Antonio José Porto

    2012-02-01

    Full Text Available The study was carried with the objective of evaluate the survival, development and cocoons production of silkworm fed with mulberry leaves (Cultivar IZ 56/4 from branches stored in warehouse(24 hours or stored in the system of covering with wet cloth and immersion of bases in water, for a period of 72 hours. It was used a completely randomized design, with two treatments and six replications. Caterpillars fed with mulberry leaves from branches stored in the system of covering and immersion for 72 hours had conditions suitable for survival, development and production of cocoon, not differing from those who received leaves from branches stored in the warehouse.

  17. Growth and survival of blowfly Lucilia sericata larvae under simulated wound conditions: implications for maggot debridement therapy.

    Science.gov (United States)

    Čičková, H; Kozánek, M; Takáč, P

    2015-12-01

    Maggot debridement therapy has become a well-established method of wound debridement. Despite its success, little information is available about the optimum duration of the treatment cycle and larval growth in wounds. This study examines the development of Lucilia sericata (Diptera: Calliphoridae) larvae under two containment conditions (bagged and free range) under simulated wound conditions and assesses the impact of transport and further storage of larvae on their survival and growth. There was no significant difference in size between bagged and free-range larvae over the 72-h experimental period. Larvae grew fastest 8-24 h after inoculation and completed their growth at 40-48 h. Mortality rates were similar (0.12-0.23% per hour) in both containment conditions and did not differ significantly (P = 0.3212). Survival of free-range larvae was on average 16% lower than survival of bagged larvae. Refrigeration of larvae upon simulated delivery for > 1 day reduced their survival to < 50% and caused a reduction in growth of up to 30% at 12 h, but not at 48 h, of incubation. Therefore, it is recommended that free-range larvae are left in the wound for a maximum of 40-48 h, and bagged larvae for 48-72 h. Larvae should be used within 24 h of delivery to avoid high mortality caused by prolonged refrigeration. © 2015 The Royal Entomological Society.

  18. Martian 'Kitchen Sponge'

    Science.gov (United States)

    2000-01-01

    This picture is illuminated by sunlight from the upper left. It shows a tiny 1 kilometer by 1 kilometer (0.62 x 0.62 mile) area of the martian north polar residual ice cap as it appears in summertime.The surface looks somewhat like that of a kitchen sponge--it is flat on top and has many closely-spaced pits of no more than 2 meters (5.5 ft) depth. The upper, flat surface in this image has a medium-gray tone, while the pit interiors are darker gray. Each pit is generally 10 to 20 meters (33-66 feet) across. The pits probably form as water ice sublimes--going directly from solid to vapor--during the martian northern summer seasons. The pits probably develop over thousands of years. This texture is very different from what is seen in the south polar cap, where considerably larger and more circular depressions are found to resemble slices of swiss cheese rather than a kitchen sponge.This picture was taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during northern summer on March 8, 1999. It was one of the very last 'calibration' images taken before the start of the Mapping Phase of the MGS mission, and its goal was to determine whether the MOC was properly focused. The crisp appearance of the edges of the pits confirmed that the instrument was focused and ready for its 1-Mars Year mapping mission. The scene is located near 86.9oN, 207.5oW, and has a resolution of about 1.4 meters (4 ft, 7 in) per pixel.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  19. The Martian geomorphology as mapped by the Mars Express High Resolution Stereo Camera (HRSC): Implications for Geological Processes and Climate Conditions.

    Science.gov (United States)

    Roatsch, T.; Jaumann, R.; Neukum, G.; Tirsch, D.; Hauber, E.; Hoffmann, H.; Gwinner, K.; Scholten, F.; Di Achille, G.; Duxbury, T. C.; Erkeling, G.; vanGasselt, S.; Gupta, S.; Head, J. W., III; Hiesinger, H.; Ip, W. H.; Keller, H. U.; Kleinhans, M. G.; Kneissl, T.; McCord, T. B.; Muller, P.; Murray, J.; Pondrelli, M.; Platz, T.; Pinet, P. C.; Reiss, D.; Rossi, A. P.; Wendt, L.; Williams, D. A.; Mangold, N.; Spohn, T.

    2014-12-01

    After 10 years of ESA's Mars Express orbiting the planet its High Resolution Stereo Camera (HRSC) covered about 90 % of the surface in stereo and color with resolutions up to 10 m/pixel. Digital elevation models of up to 50 m grid spacing [1], generated from all suitable datasets of the stereo coverage, currently cover about 40 % of the surface [2]. The geomorphological analysis of surface features, observed by the HRSC indicate major surface modifications by endogenic and exogenic processes on all scales. Endogenic landforms (e.g., tectonic rifts, small basaltic shield volcanoes) were found to be very similar to their equivalents on Earth, suggesting that no unique processes are required to explain their formation. Volcanism may have been active up to the very recent past or even to the present, putting important constraints on thermal evolution models [e.g. 3]. The analysis of diverse landforms produced by aqueous processes revealed that surface water activity was likely episodic, but ranged in age from very ancient to very recent [e.g. 3]. Particularly important is prominent glaciation and periglacial features at several latitudes, including mountain glaciers [e.g. 3]. The identification of aqueous alteration minerals and their geological context has enabled a better understanding of paleoenvironmental conditions and pedogenetic processes [e.g. 4]. Dark dunes contain volcanic material and are evidence for the significantly dynamic surface environment, characterized by widespread erosion, transport, and redeposition [e.g. 3]. Since basically all geologic interpretations of extraterrestrial features require profound knowledge of the Earth as key reference, studies of terrestrial analogues are mandatory in planetary geology. Field work in Antarctica, Svalbard and Iceland [e.g. 5] provided a basis for the analysis of periglacial and volcanic processes, respectively. References: [1] Jaumann et al., 2007, PSS 55; [2] Gwinner et al., 2010, EPSL 294; [3] Jaumann et al

  20. Microencapsulation of a probiotic and prebiotic in alginate-chitosan capsules improves survival in simulated gastro-intestinal conditions.

    Science.gov (United States)

    Chávarri, María; Marañón, Izaskun; Ares, Raquel; Ibáñez, Francisco C; Marzo, Florencio; Villarán, María del Carmen

    2010-08-15

    Chitosan was used as a coating material to improve encapsulation of a probiotic and prebiotic in calcium alginate beads. Chitosan-coated alginate microspheres were produced to encapsulate Lactobacillus gasseri (L) and Bifidobacterium bifidum (B) as probiotics and the prebiotic quercetin (Q) with the objective of enhancing survival of the probiotic bacteria and keeping intact the prebiotic during exposure to the adverse conditions of the gastro-intestinal tract. The encapsulation yield for viable cells for chitosan-coated alginate microspheres with quercetin (L+Q and B+Q) was very low. These results, together with the study about the survival of microspheres with quercetin during storage at 4 degrees C, demonstrated that probiotic bacteria microencapsulated with quercetin did not survive. Owing to this, quercetin and L. gasseri or B. bifidum were microencapsulated separately. Microencapsulated L. gasseri and microencapsulated B. bifidum were resistant to simulated gastric conditions (pH 2.0, 2h) and bile solution (3%, 2h), resulting in significantly (pmicroencapsulation of L. gasseri and B. bifidum with alginate and a chitosan coating offers an effective means of delivery of viable bacterial cells to the colon and maintaining their survival during simulated gastric and intestinal juice. Copyright 2010 Elsevier B.V. All rights reserved.

  1. Martian cratering. II - Asteroid impact history.

    Science.gov (United States)

    Hartmann, W. K.

    1971-01-01

    This paper considers the extent to which Martian craters can be explained by considering asteroidal impact. Sections I, II, and III of this paper derive the diameter distribution of hypothetical asteroidal craters on Mars from recent Palomar-Leiden asteroid statistics and show that the observed Martian craters correspond to a bombardment by roughly 100 times the present number of Mars-crossing asteroids. Section IV discusses the early bombardment history of Mars, based on the capture theory of Opik and probable orbital parameters of early planetesimals. These results show that the visible craters and surface of Mars should not be identified with the initial, accreted surface. A backward extrapolation of the impact rates based on surviving Mars-crossing asteroids can account for the majority of Mars craters over an interval of several aeons, indicating that we see back in time no further than part-way into a period of intense bombardment. An early period of erosion and deposition is thus suggested. Section V presents a comparison with results and terminology of other authors.

  2. Pressurized Martian-Like Pure CO2 Atmosphere Supports Strong Growth of Cyanobacteria, and Causes Significant Changes in their Metabolism

    Science.gov (United States)

    Murukesan, Gayathri; Leino, Hannu; Mäenpää, Pirkko; Ståhle, Kurt; Raksajit, Wuttinun; Lehto, Harry J.; Allahverdiyeva-Rinne, Yagut; Lehto, Kirsi

    2016-03-01

    Surviving of crews during future missions to Mars will depend on reliable and adequate supplies of essential life support materials, i.e. oxygen, food, clean water, and fuel. The most economical and sustainable (and in long term, the only viable) way to provide these supplies on Martian bases is via bio-regenerative systems, by using local resources to drive oxygenic photosynthesis. Selected cyanobacteria, grown in adequately protective containment could serve as pioneer species to produce life sustaining substrates for higher organisms. The very high (95.3 %) CO2 content in Martian atmosphere would provide an abundant carbon source for photo-assimilation, but nitrogen would be a strongly limiting substrate for bio-assimilation in this environment, and would need to be supplemented by nitrogen fertilizing. The very high supply of carbon, with rate-limiting supply of nitrogen strongly affects the growth and the metabolic pathways of the photosynthetic organisms. Here we show that modified, Martian-like atmospheric composition (nearly 100 % CO2) under various low pressure conditions (starting from 50 mbar to maintain liquid water, up to 200 mbars) supports strong cellular growth. Under high CO2 / low N2 ratio the filamentous cyanobacteria produce significant amount of H2 during light due to differentiation of high amount of heterocysts.

  3. Conditional survival for longer-term survivors from 2000?2004 using population-based cancer registry data in Osaka, Japan

    OpenAIRE

    Ito, Yuri; Nakayama, Tomio; Miyashiro, Isao; Ioka, Akiko; Tsukuma, Hideaki

    2013-01-01

    Background We usually report five-year survival from population-based cancer registries in Japan; however these survival estimates may be pessimistic for cancer survivors, because many patients with unfavourable prognosis die shortly after diagnosis. Conditional survival can provide relevant information for cancer survivors, their family and oncologists. Methods We used the period approach to estimate the latest 10-year survival of 38,439 patients with stomach, colorectal, lung, breast and pr...

  4. Climate change, phenology, and habitat degradation: drivers of gosling body condition and juvenile survival in lesser snow geese.

    Science.gov (United States)

    Aubry, Lise M; Rockwell, Robert F; Cooch, Evan G; Brook, Rodney W; Mulder, Christa P H; Koons, David N

    2013-01-01

    Nesting migratory geese are among the dominant herbivores in (sub) arctic environments, which have undergone unprecedented increases in temperatures and plant growing days over the last three decades. Within these regions, the Hudson Bay Lowlands are home to an overabundant breeding population of lesser snow geese that has dramatically damaged the ecosystem, with cascading effects at multiple trophic levels. In some areas the overabundance of geese has led to a drastic reduction in available forage. In addition, warming of this region has widened the gap between goose migration timing and plant green-up, and this 'mismatch' between goose and plant phenologies could in turn affect gosling development. The dual effects of climate change and habitat quality on gosling body condition and juvenile survival are not known, but are critical for predicting population growth and related degradation of (sub) arctic ecosystems. To address these issues, we used information on female goslings marked and measured between 1978 and 2005 (4125 individuals). Goslings that developed within and near the traditional center of the breeding colony experienced the effects of long-term habitat degradation: body condition and juvenile survival declined over time. In newly colonized areas, however, we observed the opposite pattern (increase in body condition and juvenile survival). In addition, warmer than average winters and summers resulted in lower gosling body condition and first-year survival. Too few plant 'growing days' in the spring relative to hatch led to similar results. Our assessment indicates that geese are recovering from habitat degradation by moving to newly colonized locales. However, a warmer climate could negatively affect snow goose populations in the long-run, but it will depend on which seasons warm the fastest. These antagonistic mechanisms will require further study to help predict snow goose population dynamics and manage the trophic cascade they induce. © 2012

  5. Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions.

    Science.gov (United States)

    Johansen, Anders; Nielsen, Henrik B; Hansen, Christian M; Andreasen, Christian; Carlsgart, Josefine; Hauggard-Nielsen, Henrik; Roepstorff, Allan

    2013-04-01

    Anaerobic digestion of residual materials from animals and crops offers an opportunity to simultaneously produce bioenergy and plant fertilizers at single farms and in farm communities where input substrate materials and resulting digested residues are shared among member farms. A surplus benefit from this practice may be the suppressing of propagules from harmful biological pests like weeds and animal pathogens (e.g. parasites). In the present work, batch experiments were performed, where survival of seeds of seven species of weeds and non-embryonated eggs of the large roundworm of pigs, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37°C) and thermophilic (55°C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55°C) was very clear as complete mortality, irrespective of weed species, was reached after less than 2 days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzinckia micrantha still maintained low levels (~1%) of germination ability after 1 week. Chenopodium album was the only weed species which survived 1 week at substantial levels (7%) although after 11 d germination ability was totally lost. Similarly, at 55°C, no Ascaris eggs survived more than 3h of incubation. Incubation at 37°C did not affect egg survival during the first 48 h and it took up to 10 days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites and weeds so that the digestates can be applied without risking spread of these pests. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Martian weathering processes: Terrestrial analog and theoretical modeling studies

    Science.gov (United States)

    McAdam, Amy Catherine

    2008-06-01

    Understanding the role of water in the Martian near-surface, and its implications for possible habitable environments, is among the highest priorities of NASA's Mars Exploration Program. Characterization of alteration signatures in surface materials provides the best opportunity to assess the role of water on Mars. This dissertation investigates Martian alteration processes through analyses of Antarctic analogs and numerical modeling of mineral-fluid interactions. Analog work involved studying an Antarctic diabase, and associated soils, as Mars analogs to understand weathering processes in cold, dry environments. The soils are dominated by primary basaltic minerals, but also contain phyllosilicates, salts, iron oxides/oxyhydroxides, and zeolites. Soil clay minerals and zeolites, formed primarily during deuteric or hydrothermal alteration of the parent rock, were subsequently transferred to the soil by physical rock weathering. Authigenic soil iron oxides/oxyhydroxides and small amounts of poorly-ordered secondary silicates indicate some contributions from low-temperature aqueous weathering. Soil sulfates, which exhibit a sulfate- aerosol-derived mass-independent oxygen isotope signature, suggest contributions from acid aerosol-rock interactions. The complex alteration history of the Antarctic materials resulted in several similarities to Martian materials. The processes that affected the analogs, including deuteric/ hydrothermal clay formation, may be important in producing Martian surface materials. Theoretical modeling focused on investigating the alteration of Martian rocks under acidic conditions and using modeling results to interpret Martian observations. Kinetic modeling of the dissolution of plagioclase-pyroxene mineral mixtures under acidic conditions suggested that surfaces with high plagioclase/pyroxene, such as several northern regions, could have experienced some preferential dissolution of pyroxenes at a pH less than approximately 3-4. Modeling of the

  7. Magnesium Based Rockets for Martian Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop Mg rockets for Martian ascent vehicle applications. The propellant can be acquired in-situ from MgO in the Martian regolith (5.1% Mg by mass)...

  8. Terrestrial Permafrost Models of Martian Habitats and Inhabitants

    Science.gov (United States)

    Gilichinsky, D.

    2011-12-01

    The terrestrial permafrost is the only rich depository of viable ancient microorganisms on Earth, and can be used as a bridge to possible Martian life forms and shallow subsurface habitats where the probability of finding life is highest. Since there is a place for water, the requisite condition for life, the analogous models are more or less realistic. If life ever existed on Mars, traces might have been preserved and could be found at depth within permafrost. The age of the terrestrial isolates corresponds to the longevity of the frozen state of the embedding strata, with the oldest known dating back to the late Pliocene in Arctic and late Miocene in Antarctica. Permafrost on Earth and Mars vary in age, from a few million years on Earth to a few billion years on Mars. Such a difference in time scale would have a significant impact on the possibility of preserving life on Mars, which is why the longevity of life forms preserved within terrestrial permafrost can only be an approximate model for Mars. 1. A number of studies indicate that the Antarctic cryosphere began to develop on the Eocene-Oligocene boundary, after the isolation of the continent. Permafrost degradation is only possible if mean annual ground temperature, -28°C now, rise above freezing, i.e., a significant warming to above 25°C is required. There is no evidence of such sharp temperature increase, which indicates that the climate and geological history was favorable to persistence of pre-Pliocene permafrost. These oldest relics (~30Myr) are possibly to be found at high hypsometric levels of ice-free areas (Dry Valleys and nearby mountains). It is desirable to test the layers for the presence of viable cells. The limiting age, if one exists, within this ancient permafrost, where the viable organisms were no longer present, could be established as the limit for life preservation below 0oC. Positive results will extend the known temporal limits of life in permafrost. 2. Even in this case, the age of

  9. Liquid Water in the Extremely Shallow Martian Subsurface

    Science.gov (United States)

    Pavlov, A.; Shivak, J. N.

    2012-01-01

    Availability of liquid water is one of the major constraints for the potential Martian biosphere. Although liquid water is unstable on the surface of Mars due to low atmospheric pressures, it has been suggested that liquid films of water could be present in the Martian soil. Here we explored a possibility of the liquid water formation in the extremely shallow (1-3 cm) subsurface layer under low atmospheric pressures (0.1-10 mbar) and low ("Martian") surface temperatures (approx.-50 C-0 C). We used a new Goddard Martian simulation chamber to demonstrate that even in the clean frozen soil with temperatures as low as -25C the amount of mobile water can reach several percents. We also showed that during brief periods of simulated daylight warming the shallow subsurface ice sublimates, the water vapor diffuses through porous surface layer of soil temporarily producing supersaturated conditions in the soil, which leads to the formation of additional liquid water. Our results suggest that despite cold temperatures and low atmospheric pressures, Martian soil just several cm below the surface can be habitable.

  10. Martian meteorite Dhofar 019: A new shergottite

    Science.gov (United States)

    Taylor, L. A.; Nazarov, M. A.; Shearer, C. K.; McSween, H. Y., Jr.; Cahill, J.; Neal, C. R.; Ivanova, M. A.; Barsukova, L. D.; Lentz, R. C.; Clayton, R. N.; Mayeda, T. K.

    2002-08-01

    Dhofar 019 is a new martian meteorite found in the desert of Oman. In texture, mineralogy, and major and trace element chemistry, this meteorite is classified as a basaltic shergottite. Olivine megacrysts are set within a groundmass composed of finer grained olivine, pyroxene (pigeonite and augite), and maskelynite. Minor phases are chromite-ulvöspinel, ilmenite, silica, K-rich feldspar, merrillite, chlorapatite, and pyrrhotite. Secondary phases of terrestrial origin include calcite, gypsum, celestite, Fe hydroxides, and smectite. Dhofar 019 is most similar to the Elephant Moraine (EETA) 79001 lithology A and Dar al Gani (DaG) 476/489 shergottites. The main features that distinguish Dhofar 019 from other shergottites are lack of orthopyroxene; lower Ni contents of olivine; the heaviest oxygen-isotopic bulk composition; and larger compositional ranges for olivine, maskelynite, and spinel, as well as a wide range for pyroxenes. The large compositional ranges of the minerals are indicative of relatively rapid crystallization. Modeling of olivine chemical zonations yield minimum cooling rates of 0.5-0.8 ?C/h. Spinel chemistry suggests that crystallization took place under one of the most reduced conditions for martian meteorites, at an oxygen fugacity of 3 log units below the quartz-fayalite-magnetite (QFM) buffer. The olivine megacrysts are heterogeneously distributed in the rock. Crystal size distribution analysis suggests that they constitute a population formed under steady-state conditions of nucleation and growth, although a few grains may be cumulates. The parent melt is thought to have been derived from partial melting of a light rare earth element- and platinum group element-depleted mantle source. Shergottites, EETA79001 lithology A, DaG 476/489, and Dhofar 019, although of different ages, comprise a particular type of martian rocks. Such rocks could have formed from chemically similar source(s) and parent melt(s), with their bulk compositions affected by

  11. Survivability of Salmonella typhimurium L1388 and Salmonella enteritidis L1225 under stressful growth conditions

    Directory of Open Access Journals (Sweden)

    Ngwai YB

    2007-11-01

    Full Text Available In an earlier study with Salmonella typhimurium L1388 (ST and Salmonella enteritidis L1225 (SE isolated from diseased chickens, we found that SE formed more biofilm than ST on abiotic surfaces in a time-dependent manner. Since the ability of salmonellae to survive extreme environment is related to their virulence, the present study examined the survival of Salmonella typhimurium L1388 and Salmonella nteritidis L1225 under the usual stresses that salmonellae encounter during their life cycle. This is with a view to understanding the strains’ stress tolerance that could be used to explain their virulence. Incubation at 37oC for various time periods was done for: i stationary phase (SP cells at pH 2.6; ii log-phase (LP cells at pH 4.0; log-phase or stationary phase cells in broth containing iii hydrogen peroxide, iv sodium chloride and v ethanol; vi stationary phase cells in Hank’s balanced salt solution (single strength containing 10% human serum; and vii prolong stationary phase cells. Stationary phase cells were also incubated at 52oC for 15 min. Surviving cells at the various incubation times were counted on trypticase soy agar (TSA after appropriate dilution in saline and overnight incubation at 37oC. Growth iron-poor medium was determined by growing a single bacterial colony in Medium A with shaking at 37oC or 40oC for 24 h. Statistics was done by one-way analysis-of-variance (ANOVA at P = 0.05. Differences in the survival of ST and SE were insignificant (p>0.05 in acid pH at both pH 4.0 (p = 0.3783 and pH 2.6 (p = 0.4711; at high salinity for log-phase (p = 0.1416 and stationary phase (p = 0.1816 cells; in ethanol (p = 0.5984, human serum (p = 0.8139, prolonged stationary phase (p = 0.3506; and under heat (p = 0.5766. SE was significantly (p<0.05; p = 0.0031 more tolerant to oxidative-killing by hydrogen peroxide. Culturable growth of the ST and SE in an iron-poor medium A revealed insignificant differences at 37oC (p = 0.8381 but

  12. Desert spring mounds: a potential analogue to Martian arid environments?

    Science.gov (United States)

    Franchi, F.; Frisia, S.

    2017-09-01

    Spring carbonates have been often considered as putative analogues of Martian arid environments. On Earth these are believed to form by the interaction of highly saline water and microbial communities, which favor the formation of authigenic micrite. Here we present new data from spring mounds in the western Makgadikgadi Pan (Botswana) and the Great Artesian Basin (South Australia). In both areas, upwelling of ground water give rise to mounds and layered deposits which are close morphological analogues of landforms documented on Mars. The authigenic carbonates and evaporites associated with the spring mounds retain evidence of microbial microfabric founded elsewhere, pointing to the potential existence of similar microbial in the extreme Martian conditions.

  13. Conditional disease-free survival after surgical resection of gastrointestinal stromal tumors: a multi-institutional analysis of 502 patients.

    Science.gov (United States)

    Bischof, Danielle A; Kim, Yuhree; Dodson, Rebecca; Jimenez, M Carolina; Behman, Ramy; Cocieru, Andrei; Fisher, Sarah B; Groeschl, Ryan T; Squires, Malcolm H; Maithel, Shishir K; Blazer, Dan G; Kooby, David A; Gamblin, T Clark; Bauer, Todd W; Quereshy, Fayez A; Karanicolas, Paul J; Law, Calvin H L; Pawlik, Timothy M

    2015-04-01

    Gastrointestinal stromal tumors (GISTs) are the most commonly diagnosed mesenchymal tumors of the gastrointestinal tract. The risk of recurrence following surgical resection of GISTs is typically reported from the date of surgery. However, disease-free survival (DFS) over time is dynamic and changes based on disease-free time already accumulated following surgery. To assess the comparative performance of established GIST recurrence risk prognostic scoring systems and to characterize conditional DFS following surgical resection of GISTs. A retrospective cohort study of 502 patients who underwent surgery for a primary, nonmetastatic GIST between January 1, 1998, and December 31, 2012, at 7 major academic cancer centers in the United States and Canada. Disease-free survival of the patients was classified according to 5 prognostic scoring systems, including the National Institutes of Health criteria, modified National Institutes of Health criteria, Memorial Sloan Kettering Cancer Center GIST nomogram, and American Joint Committee on Cancer gastric and nongastric categories. The concordance index (also known as the C statistic or the area under the receiver operating curve) of established GIST recurrence risk prognostic scoring systems. Conditional DFS estimates were calculated. Overall 1-year, 3-year, and 5-year DFS following resection of GISTs was 95%, 83%, and 74%, respectively. All the prognostic scoring systems had fair prognostic ability. For all tumor sites, the American Joint Committee on Cancer gastric category demonstrated the best discrimination (C = 0.79). Using conditional DFS, the probability of remaining disease free for an additional 3 years given that a patient was disease free at 1 year, 3 years, and 5 years was 82%, 89%, and 92%, respectively. Patients with the highest initial recurrence risk demonstrated the greatest increase in conditional survival as time elapsed. Conditional DFS improves over time following resection of GISTs. This is valuable

  14. Increased survival in the red flour beetle after oral priming with bacteria-conditioned media.

    Science.gov (United States)

    Milutinović, Barbara; Fritzlar, Svenja; Kurtz, Joachim

    2014-01-01

    Immune priming is defined as enhanced protection upon secondary exposure to a pathogen. Such enhanced resistance after prior exposure has been demonstrated for a number of insect species including the red flour beetle, Tribolium castaneum. In testing this phenomenon, the majority of studies have focused on introducing the pathogen into the insect's hemocoel via septic wounding through the cuticle. Although such septic injury can occur in nature, many pathogens enter their hosts via the oral route, i.e. by ingestion. Bacillus thuringiensis bacteria are well-known insect pathogens that infect their host orally. We found that T. castaneum larvae showed increased survival after oral exposure to B. thuringiensis, when they had been orally primed with filter-sterilized media in which spores of B. thuringiensis had been raised. Such priming was achieved only with a naturally pathogenic strain of B. thuringiensis and a strain that was made pathogenic by transfer of plasmids. Moreover, primed larvae were smaller in size 24 h after priming and had a longer developmental time, indicating that investment in such a response comes at a cost. However, the increased survival in primed larvae was not caused by larval size differences upon challenge. © 2013 S. Karger AG, Basel.

  15. SABIA (Mimosa caesalpiniaefolia Benth. SEEDLINGS GROWTH AND SURVIVAL INOCULATED WITH SYMBIOTIC MICROORGANISMS IN FIELD CONDITIONS

    Directory of Open Access Journals (Sweden)

    Marília Malta Cavalcante Mendes

    2013-06-01

    Full Text Available http://dx.doi.org/10.5902/198050989277Sabia (Mimosa caesalpiniaefolia Benth. has ecological characteristics and symbiotic associations with nitrogen fixing bacteria and arbuscular mycorrhizal fungi. These associations are used as biological tool that could be used as an able alternative to minimize chemical fertilizer use and benefit plant development at environments under nutritional deficit. The objective of this study was to evaluate the growth of Leguminosae Sabia (Mimosa caesalpiniaefolia Benth. like response to rhizobium and arbuscular mycorrhizal fungi inoculation, to establish growth curves to height and stem based diameter, to determine the N and F contents in plants aerial parts and to evaluate plants survival at field. The strain used was BR3405, The arbuscular mycorrhizal fungi used was Glomus clarum and Gigaspora margarita. The Glomus clarum + Gigaspora margarita + BR3405 and Gigaspora margarita inoculation provided better values for the studied variables (height, diameter, N and P , and this last one was the best choice to Sabia plantation. The plants showed 100% survival, regardless the treatment ued. There was not significant statistical difference for N and F content in Sabia aerial part., Nevertheless, it was noticed a faster growth in plants with symbiont.

  16. Geriatric Conditions in Acutely Hospitalized Older Patients: Prevalence and One-Year Survival and Functional Decline

    NARCIS (Netherlands)

    Buurman, B.M.; Hoogerduijn, J.G.; de Haan, R.J.; Abu-Hanna, A.; Lagaay, A.M.; Verhaar, H.J.; Schuurmans, M.J.; Levi, M.; de Rooij, S.E.

    2011-01-01

    Background: To study the prevalence of eighteen geriatric conditions in older patients at admission, their reporting rate in discharge summaries and the impact of these conditions on mortality and functional decline one year after admission. Method: A prospective multicenter cohort study conducted

  17. The impact of meteoritic impacts on the early Martian environment

    Science.gov (United States)

    Turbet, M.; Forget, F.; Svetsov, V.; Tran, H.; Karatekin, O.; Popova, O.; Gillmann, C.

    2017-09-01

    We model the environmental effect of meteoritic impacts on Early Mars ( 3.8Gy ago) by combining an hydrocode with a Global Climate Model. We explore if these impact events could trigger the warm & wet conditions, and the precipitation rates required to explain the formation of the Martian valley networks.

  18. Mars-relevant phosphate minerals and implications for Martian habitability

    Science.gov (United States)

    Adcock, Christopher T.

    This dissertation is comprised of three studies focused on martian phosphate availability, with an introductory chapter introducing and linking the three studies. Chapter two is on the subject of merrillite synthesis. Merrillite is an extraterrestrial Ca-phosphate mineral similar to the mineral whitlockite and is found as a dominant primary phosphate mineral in martian meteorites. The chapter includes methods of whitlockite and merrillite synthesis as well as a detailed characterization of the produced minerals and a mechanism by which charge balance can be maintained when merrillite is synthesized through dehydrogenation of whitlockite. Chapter three presents the results of kinetic and thermodynamic studies on the Mars-relevant minerals chlorapatite and merrillite, as well as the more terrestrially-relevant minerals whitlockite and fluorapatite. The results of these studies indicate that the dominant primary Ca-phosphate minerals on Mars possess higher solubilities that could lead to more than twice the phosphate concentration in solution. Dissolution rates for the Mars-relevant minerals derived in the study, when combined with the higher martian phosphorus abundance, could result in phosphate release rates of up to 45x faster for a given set of aqueous conditions on Mars when compared to Earth. The implications of the results for past or present martian habitability are discussed. In Chapter four, reactive transport modeling was applied to investigate the transport and mobility of phosphate under martian conditions. The kinetic and thermodynamic data derived in Chapter three were combined with Mars mission data, results from an investigation of Mars analog basalts at Craters of the Moon National Monument in Idaho, and previously published data to inform a reactive transport code and model dissolution profiles measured by Mars Exploration Rover (MER) Spirit in Wishstone class rocks. The modeling results suggest phosphate release into near-neutral waters occurred

  19. Retention of stored water enables tropical tree saplings to survive extreme drought conditions.

    Science.gov (United States)

    Wolfe, Brett T

    2017-04-01

    Trees generally maintain a small safety margin between the stem water potential (Ψstem) reached during seasonal droughts and the Ψstem associated with their mortality. This pattern may indicate that species face similar mortality risk during extreme droughts. However, if tree species vary in their ability to regulate Ψstem, then safety margins would poorly predict drought mortality. To explore variation among species in Ψstem regulation, I subjected potted saplings of six tropical tree species to extreme drought and compared their responses with well-watered plants and pretreatment reference plants. In the drought treatment, soil water potential reached Bursera simaruba (L.) Sarg., Cavanillesia platanifolia (Bonpl.) Kunth and Cedrela odorata L. had 100% survival and maintained Ψstem near -1 MPa (i.e., desiccation-avoiding species). Three other species, Cojoba rufescens (Benth.) Britton and Rose, Genipa americana L. and Hymenaea courbaril L. had 50%, 0% and 25% survival, respectively, and survivors had Ψstem <-6 MPa (i.e., desiccation-susceptible species). The desiccation-avoiding species had lower relative water content (RWC) in all organs and tissues (root, stem, bark and xylem) in the drought treatment than in the reference plants (means 72.0-90.4% vs 86.9-97.9%), but the survivors of the desiccation-susceptible C. rufescens had much lower RWC in the drought treatment (44.5-72.1%). Among the reference plants, the desiccation-avoiding species had lower tissue density, leaf-mass fraction and lateral-root surface area (LRA) than the desiccation-susceptible species. Additionally, C. platanifolia and C. odorata had reduced LRA in the drought treatment, which may slow water loss into dry soil. Together, these results suggest that the ability to regulate Ψstem during extreme drought is associated with functional traits that favor retention of stored water and that safety margins during seasonal drought poorly predict survival during extreme drought. © The Author

  20. Fecundity, growth, and survival of the angelfish Pterophyllum scalare (Perciformes: Cichlidae under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Armando A Ortega-Salas

    2009-09-01

    Full Text Available The freshwater angelfishes (Pterophyllum are South American cichlids that have become very popular among aquarists, yet scarce information on their culture and aquarium husbandry exists. We studied Pterophyllum scalare to analyze dietary effects on fecundity, growth, and survival of eggs and larvae during 135 days. Three diets were used: A decapsulated cysts of Artemia, B commercial dry fish food, and C a mix diet of the rotifer Brachionus plicatilis and the cladoceran Daphnia magna. The initial larval density was 100 organisms in each 40L aquarium. With diet A, larvae reached a maximum weight of 3.80g, a total length of 6.3 cm, and a height of 5.8cm; with diet B: 2.80g, 4.81cm, and 4.79cm, and with diet C: 3.00g, 5.15cm, and 5.10cm, respectively. Significant differences were observed between diet A, and diet B and C, but no significantly differences were observed between diets B and C. Fecundity varied from 234 to 1 082 eggs in 20 and 50g females, respectively. Egg survival ranged from 87.4% up to 100%, and larvae survival (80 larvae/40L aquarium from 50% to 66.3% using diet B and A, respectively. Live food was better for growing fish than the commercial balanced food diet. Fecundity and survival are important factors in planning a good production of angelfish. Rev. Biol. Trop. 57 (3: 741-747. Epub 2009 September 30.Se realizaron estudios de cultivo en laboratorio del pez ángel, Pterophyllum scalare, para analizar los efectos de su dieta en la fecundidad, crecimiento y sobrevivencia en huevos y larvas por un período 135 días. Tres dietas diferentes se utilizaron A quistes decapsulados de Artemia, B comida comercial seca para pez, C una mezcla de rotíferos, Brachionus plicatilis y el cladocero, Daphnia magna. La densidad inicial de larvas en acuarios de 40L fue de 100 organismos. Utilizando la dieta A, las larvas alcanzaron un peso máximo de 3.80g, una longitud total de 6.3cm y una altura de 5.8cm; utilizando la dieta B, fue de 2.80g, 4

  1. Physicochemical properties of concentrated Martian surface waters

    Science.gov (United States)

    Tosca, Nicholas J.; McLennan, Scott M.; Lamb, Michael P.; Grotzinger, John P.

    2011-05-01

    Understanding the processes controlling chemical sedimentation is an important step in deciphering paleoclimatic conditions from the rock records preserved on both Earth and Mars. Clear evidence for subaqueous sedimentation at Meridiani Planum, widespread saline mineral deposits in the Valles Marineris region, and the possible role of saline waters in forming recent geomorphologic features all underscore the need to understand the physical properties of highly concentrated solutions on Mars in addition to, and as a function of, their distinct chemistry. Using thermodynamic models predicting saline mineral solubility, we generate likely brine compositions ranging from bicarbonate-dominated to sulfate-dominated and predict their saline mineralogy. For each brine composition, we then estimate a number of thermal, transport, and colligative properties using established models that have been developed for highly concentrated multicomponent electrolyte solutions. The available experimental data and theoretical models that allow estimation of these physicochemical properties encompass, for the most part, much of the anticipated variation in chemistry for likely Martian brines. These estimates allow significant progress in building a detailed analysis of physical sedimentation at the ancient Martian surface and allow more accurate predictions of thermal behavior and the diffusive transport of matter through chemically distinct solutions under comparatively nonstandard conditions.

  2. Osteocalcin protects pancreatic beta cell function and survival under high glucose conditions.

    Science.gov (United States)

    Kover, Karen; Yan, Yun; Tong, Pei Ying; Watkins, Dara; Li, Xiaoyu; Tasch, James; Hager, Melissa; Clements, Mark; Moore, Wayne V

    2015-06-19

    Diabetes is characterized by progressive beta cell dysfunction and loss due in part to oxidative stress that occurs from gluco/lipotoxicity. Treatments that directly protect beta cell function and survival in the diabetic milieu are of particular interest. A growing body of evidence suggests that osteocalcin, an abundant non-collagenous protein of bone, supports beta cell function and proliferation. Based on previous gene expression data by microarray, we hypothesized that osteocalcin protects beta cells from glucose-induced oxidative stress. To test our hypothesis we cultured isolated rat islets and INS-1E cells in the presence of normal, high, or high glucose ± osteocalcin for up to 72 h. Oxidative stress and viability/mitochondrial function were measured by H2O2 assay and Alamar Blue assay, respectively. Caspase 3/7 activity was also measured as a marker of apoptosis. A functional test, glucose stimulated insulin release, was conducted and expression of genes/protein was measured by qRT-PCR/western blot/ELISA. Osteocalcin treatment significantly reduced high glucose-induced H2O2 levels while maintaining viability/mitochondrial function. Osteocalcin also significantly improved glucose stimulated insulin secretion and insulin content in rat islets after 48 h of high glucose exposure compared to untreated islets. As expected sustained high glucose down-regulated gene/protein expression of INS1 and BCL2 while increasing TXNIP expression. Interestingly, osteocalcin treatment reversed the effects of high glucose on gene/protein expression. We conclude that osteocalcin can protect beta cells from the negative effects of glucose-induced oxidative stress, in part, by reducing TXNIP expression, thereby preserving beta cell function and survival. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Absence of a Socioeconomic Gradient in Older Adults' Survival with Multiple Chronic Conditions

    Directory of Open Access Journals (Sweden)

    Natasha E. Lane

    2015-12-01

    Interpretation: Among older adults with universal access to health care, the deleterious effect of increasing chronic condition burden on two-year hazard of death was consistent across neighborhood income quintiles once baseline differences in condition burden were accounted for. This may be partly attributable to equal access to, and utilization of, health care. Alternate explanations for these findings, including study limitations, are also discussed.

  4. Geriatric Conditions in Acutely Hospitalized Older Patients: Prevalence and One-Year Survival and Functional Decline

    Science.gov (United States)

    Buurman, Bianca M.; Hoogerduijn, Jita G.; de Haan, Rob J.; Abu-Hanna, Ameen; Lagaay, A. Margot; Verhaar, Harald J.; Schuurmans, Marieke J.; Levi, Marcel; de Rooij, Sophia E.

    2011-01-01

    Background To study the prevalence of eighteen geriatric conditions in older patients at admission, their reporting rate in discharge summaries and the impact of these conditions on mortality and functional decline one year after admission. Method A prospective multicenter cohort study conducted between 2006 and 2008 in two tertiary university teaching hospitals and one regional teaching hospital in the Netherlands. Patients of 65 years and older, acutely admitted and hospitalized for at least 48 hours, were invited to participate. Eighteen geriatric conditions were assessed at hospital admission, and outcomes (mortality, functional decline) were assessed one year after admission. Results 639 patients were included, with a mean age of 78 years. IADL impairment (83%), polypharmacy (61%), mobility difficulty (59%), high levels of primary caregiver burden (53%), and malnutrition (52%) were most prevalent. Except for polypharmacy and cognitive impairment, the reporting rate of the geriatric conditions in discharge summaries was less than 50%. One year after admission, 35% had died and 33% suffered from functional decline. A high Charlson comorbidity index score, presence of malnutrition, high fall risk, presence of delirium and premorbid IADL impairment were associated with mortality and overall poor outcome (mortality or functional decline). Obesity lowered the risk for mortality. Conclusion Geriatric conditions were highly prevalent and associated with poor health outcomes after admission. Early recognition of these conditions in acutely hospitalized older patients and improving the handover to the general practitioner could lead to better health outcomes and reduce the burden of hospital admission for older patients. PMID:22110598

  5. Simulation and Validation of Cisco Lethal Conditions in Minnesota Lakes under Past and Future Climate Scenarios Using Constant Survival Limits

    Directory of Open Access Journals (Sweden)

    Liping Jiang

    2016-07-01

    Full Text Available Fish habitat in lakes is strongly constrained by water temperature (T and available dissolved oxygen (DO that are changed under climate warming. A one dimensional, dynamic water quality model MINLAKE2012 was used for T and DO simulation over 48 years. A fish habitat model FishHabitat2013 using simulated T and DO profiles as input was developed to determine lethal conditions of cisco Corgenous artedi in Minnesota lakes. Twenty-three lakes that had observations of cisco mortality or survival in the unusually warm summer of 2006 were used for model validation. The cisco habitat model used a lethal temperature of 22.1 °C and DO survival limit of 3 mg/L determined through model validation and sensitivity analysis. Cisco lethal conditions in 12 shallow, 16 medium-depth, and 30 deep virtual lakes were then simulated. Isopleths of total number of years with cisco kill and average cisco kill days for the years with kills under past (1961–2008 and future climate were generated to understand/extrapolate climate impacts on cisco in 620 Minnesota lakes. Shallow and medium-depth lakes are projected to not be good candidates for cisco refuge lakes, but deep lakes are possible cisco refuge lakes based on lethal condition projection under future warmer climate.

  6. Food matrices and cell conditions influence survival of Lactobacillus rhamnosus GG under heat stresses and during storage.

    Science.gov (United States)

    Endo, Akihito; Teräsjärvi, Johanna; Salminen, Seppo

    2014-03-17

    The present study evaluated impact of moisture content and cell conditions on survival of probiotic strain, Lactobacillus rhamnosus GG, under lethal heat stresses and during long-term storage using freeze-dried cells and oils as matrices. Viable cell counts of freeze-dried L. rhamnosus GG cells suspended in oils had only 1-log-reduction after 5min at 80°C and approximately 3-log-reduction after 20min, while no or very few viable cells were recorded for freeze dried cells suspended in buffer and cultured cells in oils. Surprisingly, freeze-dried cells suspended in oils still contained 4.3 to 6.7logCFU/ml after 5min at 95°C. Long-term storage study indicated that freeze-dried cells suspended in oils kept viable conditions for 4months, and a loss of the viability was only 0.3 to 0.6logCFU/ml. Viable cell counts of cultured cells suspended in oils were not present after 3days to 3months. These results clearly indicate that moisture and cell conditions have a great impact on survival of probiotics under severe heat stress in processing and during long-term storage. Combination of freeze-dried cells and oils as carrier provides beneficial options to preserve viability of probiotics in food processes and storage. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Antimicrobial effects of weak acids on the survival of Escherichia coli O157:H7 under anaerobic conditions.

    Science.gov (United States)

    Lu, Huiying J; Breidt, Frederick; Pérez-Díaz, Ilenys M; Osborne, Jason A

    2011-06-01

    Outbreaks of disease due to vegetative bacterial pathogens associated with acid foods (such as apple cider) have raised concerns about acidified vegetables and related products that have a similar pH (3.2 to 4.0). Escherichia coli O157:H7 and related strains of enterohemorrhagic E. coli (EHEC) have been identified as the most acid resistant vegetative pathogens in these products. Previous research has shown that the lack of dissolved oxygen in many hermetically sealed acid or acidified food products can enhance survival of EHEC compared with their survival under aerobic conditions. We compared the antimicrobial effects of several food acids (acetic, malic, lactic, fumaric, benzoic, and sorbic acids and sulfite) on a cocktail of EHEC strains under conditions representative of non-heat-processed acidified vegetables in hermetically sealed jars, holding the pH (3.2) and ionic strength (0.342) constant under anaerobic conditions. The overall antimicrobial effectiveness of weak acids used in this study was ranked, from most effective to least effective: sulfite > benzoic acid > sorbic acid > fumaric acid > L- and D-lactic acid > acetic acid > malic acid. These rankings were based on the estimated protonated concentrations required to achieve a 5-log reduction in EHEC after 24 h of incubation at 30°C. This study provides information that can be used to formulate safer acid and acidified food products and provides insights about the mode of action of weak acids against EHEC.

  8. Earth – Mars Similarity Criteria for Martian Vehicles

    Directory of Open Access Journals (Sweden)

    Octavian TRIFU

    2010-09-01

    Full Text Available In order to select the most efficient kind of a martian exploring vehicle, the similarity criteria are deduced from the equilibrium movement in the terrestrial and martian conditions. Different invariants have been obtained for the existing (entry capsules, parachutes and rovers and potential martian exploring vehicles (lighter-than-air vehicle, airplane, helicopter and Mars Jumper. These similarity criteria, as non dimensional numbers, allow to quickly compare if such a kind of vehicles can operate in the martian environment, the movement performances, the necessary geometrical dimensions and the power consumption. Following this way of study it was concluded what vehicle is most suitable for the near soil Mars exploration. “Mars Rover” has less power consumption on Mars, but due to the rugged terrain the performances are weak. A vacuumed rigid airship is possible to fly with high performances and endurance on Mars, versus the impossibility of such a machine on the Earth. Due to very low density and the low Reynolds numbers in the Mars atmosphere, the power consumption for the martian airplane or helicopter, is substantial higher. The most efficient vehicle for the Mars exploration it seems to be a machine using the in-situ non-chemical propellants: the 95% CO2 atmosphere and the weak solar radiation. A small compressor, electrically driven by photovoltaics, compresses the gas in a storage tank, in time. If the gas is expanded through a nozzle, sufficient lift and control forces are obtained for a VTOL flight of kilometers over the martian soil, in comparison with tens of meters of the actual Mars rovers.

  9. Identification and Characterization of Early Mission Phase Microorganisms Residing on the Mars Science Laboratory and Assessment of Their Potential to Survive Mars-like Conditions

    Science.gov (United States)

    Smith, Stephanie A.; Benardini, James N., III; Anderl, David; Ford, Matt; Wear, Emmaleen; Schrader, Michael; Schubert, Wayne; DeVeaux, Linda; Paszczynski, Andrzej; Childers, Susan E.

    2017-03-01

    Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to survive and grow on Mars. Having this knowledge is paramount to addressing whether microorganisms transported from Earth could negatively impact future space exploration. The objectives of this study were to identify cultivable microorganisms collected from the surface of the Mars Science Laboratory, to distinguish which of the cultivable microorganisms can utilize energy sources potentially available on Mars, and to determine the survival of the cultivable microorganisms upon exposure to physiological stresses present on the martian surface. Approximately 66% (237) of the 358 microorganisms identified are related to members of the Bacillus genus, although surprisingly, 22% of all isolates belong to non-spore-forming genera. A small number could grow by reduction of potential growth substrates found on Mars, such as perchlorate and sulfate, and many were resistant to desiccation and ultraviolet radiation (UVC). While most isolates either grew in media containing ≥10% NaCl or at 4°C, many grew when multiple physiological stresses were applied. The study yields details about the microorganisms that inhabit the surfaces of spacecraft after microbial reduction measures, information that will help gauge whether microorganisms from Earth pose a forward contamination risk that could impact future planetary protection policy.

  10. Whole lichen thalli survive exposure to space conditions: results of Lithopanspermia experiment with Aspicilia fruticulosa.

    Science.gov (United States)

    Raggio, J; Pintado, A; Ascaso, C; De La Torre, R; De Los Ríos, A; Wierzchos, J; Horneck, G; Sancho, L G

    2011-05-01

    The Lithopanspermia space experiment was launched in 2007 with the European Biopan facility for a 10-day spaceflight on board a Russian Foton retrievable satellite. Lithopanspermia included for the first time the vagrant lichen species Aspicilia fruticulosa from Guadalajara steppic highlands (Central Spain), as well as other lichen species. During spaceflight, the samples were exposed to selected space conditions, that is, the space vacuum, cosmic radiation, and different spectral ranges of solar radiation (λ ≥ 110, ≥200, ≥290, or ≥400 nm, respectively). After retrieval, the algal and fungal metabolic integrity of the samples were evaluated in terms of chlorophyll a fluorescence, ultrastructure, and CO(2) exchange rates. Whereas the space vacuum and cosmic radiation did not impair the metabolic activity of the lichens, solar electromagnetic radiation, especially in the wavelength range between 100 and 200 nm, caused reduced chlorophyll a yield fluorescence; however, there was a complete recovery after 72 h of reactivation. All samples showed positive rates of net photosynthesis and dark respiration in the gas exchange experiment. Although the ultrastructure of all flight samples showed some probable stress-induced changes (such as the presence of electron-dense bodies in cytoplasmic vacuoles and between the chloroplast thylakoids in photobiont cells as well as in cytoplasmic vacuoles of the mycobiont cells), we concluded that A. fruticulosa was capable of repairing all space-induced damage. Due to size limitations within the Lithopanspermia hardware, the possibility for replication on the sun-exposed samples was limited, and these first results on the resistance of the lichen symbiosis A. fruticulosa to space conditions and, in particular, on the spectral effectiveness of solar extraterrestrial radiation must be considered preliminary. Further testing in space and under space-simulated conditions will be required. Results of this study indicate

  11. Role of Listeria monocytogenes sigma(B) in survival of lethal acidic conditions and in the acquired acid tolerance response.

    Science.gov (United States)

    Ferreira, Adriana; Sue, David; O'Byrne, Conor P; Boor, Kathryn J

    2003-05-01

    The food-borne pathogen Listeria monocytogenes can acquire enhanced resistance to lethal acid conditions through multiple mechanisms. We investigated contributions of the stress-responsive alternative sigma factor, sigma(B), which is encoded by sigB, to growth phase-dependent acid resistance (AR) and to the adaptive acid tolerance response in L. monocytogenes. At various points throughout growth, we compared the relative survival of L. monocytogenes wild-type and DeltasigB strains that had been exposed to either brain heart infusion (pH 2.5) or synthetic gastric fluid (pH 2.5) with and without prior acid adaptation. Under these conditions, survival of the DeltasigB strain was consistently lower than that of the wild-type strain throughout all phases of growth, ranging from 4 orders of magnitude less in mid-log phase to 2 orders of magnitude less in stationary phase. Survival of both DeltasigB and wild-type L. monocytogenes strains increased by 6 orders of magnitude upon entry into stationary phase, demonstrating that the L. monocytogenes growth phase-dependent AR mechanism is sigma(B) independent. sigma(B)-mediated contributions to acquired acid tolerance appear to be greatest in early logarithmic growth. Loss of a functional sigma(B) reduced the survival of L. monocytogenes at pH 2.5 to a greater extent in the presence of organic acid (100 mM acetic acid) than in the presence of inorganic acid alone (HCl), suggesting that L. monocytogenes protection against organic and inorganic acid may be mediated through different mechanisms. sigma(B) does not appear to contribute to pH(i) homeostasis through regulation of net proton movement across the cell membrane or by regulation of pH(i) buffering by the GAD system under the conditions examined in this study. In summary, a functional sigma(B) protein is necessary for full resistance of L. monocytogenes to lethal acid treatments.

  12. Transient effects of tendon disconnection on the survivability of a TLP in moderate-strength hurricane conditions

    Directory of Open Access Journals (Sweden)

    Moo Hyun Kim

    2009-09-01

    Full Text Available The primary objective of this paper is to investigate the dynamic stability and survivability of a four-column classic TLP (tension-leg platform under less-than-extreme storm conditions where one or more tendons have been lost due to damage or disconnect. The transient responses of the platform and tendon tensions at the moment of disconnection are particularly underscored. The numerical simulation is based on the BE-FE hybrid hull-tendon-riser coupled dynamic analysis in time domain. Compared to the common industry practice of checking the system without a failed tendon in the beginning, the maximum tension on the neighboring tendon can be significantly increased at the moment of disconnection due to the snap-like transient effects, which can lead to unexpected failure of the total system. It is also found that the transient effects can be reduced with the presence of TTRs (top-tensioned risers with pneumatic tensioners. It is also seen that the TLP cannot survive in the 100-yr hurricane condition after losing one tendon.

  13. Trade-off mediated effects on the genetics of human survival caused by increasingly benign living conditions.

    Science.gov (United States)

    Drenos, Fotios; Westendorp, Rudi G J; Kirkwood, Thomas B L

    2006-08-01

    It is sometimes suggested that modern life, with its planned fertility and medically assisted compensation for genetic disadvantage, has greatly reduced the power of natural selection to produce significant further human evolution. However, this overlooks the very recent and dramatic changes that have occurred in the patterns of human mortality, driven by the development of increasingly benign living conditions. Where the genetics of survival are significantly influenced by life history trade-offs, as is now thought to be the case for ageing and longevity, a change in the environment can shift the optimal balance that was established through natural selection under previous conditions. We examine this possibility in the context of the dramatic recent change in the mortality pressure exerted by infectious disease using a model of a hypothetical immunogenetic trade-off that weighs survival against fecundity. Our results predict that such a change might have a significant effect on population genetics over relatively short-timescales, and they may also resolve the paradox of genes that impair fertility in present-day populations by showing how such genes might be a legacy from a powerful trade-off that has acted until very recently.

  14. Survival, food consumption and growth of Norway lobster (Nephrops norvegicus) kept in laboratory conditions.

    Science.gov (United States)

    Mente, Elena

    2010-09-01

    Successful commercial aquaculture of crustacean species is dependent on satisfying their nutritional requirements and on producing rapidly growing and healthy animals. The results of the present study provide valuable information for feeding habits and growth of Nephrops norvegicus L., 1758) under laboratory conditions. The aim of the present study was to examine food consumption, growth and physiology of the Norway lobster N. norvegicus under laboratory conditions. N. norvegicus (15 g wet weight) were distributed into 1001 tanks consisting of five numbered compartments each. They were fed the experimental diets (frozen mussels and pellets) for a period of 6 months. A group of starved Nephrops was stocked and fasted for 8 months. Although Nephrops grew well when fed the frozen mussels diet, feeding on a dry pellet feed was unsatisfactory. The starvation group, despite the fact that showed the highest mortality (50%), exhibited a remarkable tolerance to the lack of food supply. The study offers further insight by correlating the amino acid profiles of Nephrops tail muscle with the two diets. The deviations from the mussel's diet for asparagine, alanine and glutamic acid suggest a deficiency of these amino acids in this diet. The results of the present study showed that the concentrations of free amino acids are lower in relative amount than those of protein-bound amino acids, except for arginine, proline and glycine. The present study contributes to the improvement of our knowledge on nutritional requirements of the above species. © 2010 ISZS, Blackwell Publishing and IOZ/CAS.

  15. Survival, growth and condition of freshwater mussels: effects of municipal wastewater effluent.

    Directory of Open Access Journals (Sweden)

    Trey Nobles

    Full Text Available Freshwater mussels (Family Unionidae are among the most imperiled group of organisms in the world, with nearly 65% of North American species considered endangered. Anthropogenic disturbances, including altered flow regimes, habitat alteration, and pollution, are the major driver of this group's decline. We investigated the effects of tertiary treated municipal wastewater effluent on survivorship, growth, and condition of freshwater mussels in experimental cages in a small Central Texas stream. We tested the effluent effects by measuring basic physical parameters of native three ridge mussels (Amblema plicata and of non-native Asian clams (Corbicula fluminea, before and after 72-day exposure at four sites above and below a municipal wastewater treatment plant outfall. Survivorship and growth of the non-native Asian clams and growth and condition indices of the native three ridge mussels were significantly higher at the reference site above the outfall than in downstream sites. We attribute this reduction in fitness below the outfall to elevated nutrient and heavy metal concentrations, and the potential presence of other untested-for compounds commonly found in municipal effluent. These results, along with an absence of native mussels below the discharge, indicate a significant negative impact of wastewater effluent on both native and non-native mussels in the stream.

  16. Shellfish Fishery Severely Reduces Condition and Survival of Oystercatchers Despite Creation of Large Marine Protected Areas

    Directory of Open Access Journals (Sweden)

    Simon Verhulst

    2004-06-01

    Full Text Available Fisheries and other human activities pose a global threat to the marine environment. Marine protected areas (MPAs are an emerging tool to cope with such threats. In the Dutch Wadden Sea, large MPAs (covering 31% of all intertidal flats have been created to protect shellfish-eating birds and allow recovery of important habitats. Even though shellfish fishing is prohibited in these areas, populations of shellfish-eating birds in the Wadden Sea have declined sharply. The role of shellfish fisheries in these declines is hotly debated, therefore, we investigated the effectiveness of MPAs for protecting oystercatcher (Haematopus ostralegus populations. Shellfish stocks (cockles, Cerastoderma edule were substantially higher in the MPAs, but surprisingly this has not resulted in a redistribution of wintering oystercatchers. Oystercatchers in unprotected areas had less shellfish in their diet and lower condition (a combined measure of mass and haematological parameters, and their estimated mortality was 43% higher. It is likely, therefore, that shellfish fishing explains at least part of the 40% decline in oystercatcher numbers in recent years. Condition and mortality effects were strongest in males, and the population sex ratio was female biased, in agreement with the fact that males rely more on shellfish. The unprotected areas apparently function as an "ecological trap," because oystercatchers did not respond as anticipated to the artificial spatial heterogeneity in food supply. Consequently, the MPAs are effective on a local scale, but not on a global scale. Similar problems are likely to exist in terrestrial ecosystems, and distribution strategies of target species need to be considered when designing terrestrial and marine protected areas if they are to be effective.

  17. Overwinter survival of juvenile lake herring in relation to body size, physiological condition, energy stores, and food ration

    Science.gov (United States)

    Pangle, Kevin L.; Sutton, Trent M.; Kinnunen, Ronald E.; Hoff, Michael H.

    2004-01-01

    Populations of lake herring Coregonus artedi in Lake Superior have exhibited high recruitment variability over the past three decades. To improve our understanding of the mechanisms which influence year-class strength, we conducted a 225-d laboratory experiment to evaluate the effects of body size, physiological condition, energy stores, and food ration on the winter survival of age-0 lake herring. Small (total length (TL) range = 60–85 mm) and large (TL range = 86–110 mm) fish were maintained under thermal and photoperiod regimes that mimicked those in Lake Superior from October through May. Fish in each size-class were maintained at two feeding treatments: brine shrimp Artemiaspp. ad libitum and no food. The mortality of large lake herring (fed, 3.8%; starved, 20.1%) was significantly less than that of small fish (fed, 11.7%; starved, 32.0%). Body condition and crude lipid content declined for all fish over the experiment; however, these variables were significantly greater for large fed (0.68% and 9.8%) and small fed (0.65% and 7.3%) fish than large starved (0.49% and 5.7%) and small starved (0.45% and 4.8%) individuals. Final crude protein and gross energy contents were also significantly greater in large fed lake herring (17.6% and 1,966 cal/g), followed by small fed (17.1% and 1,497 cal/g), large starved (15.4% and 1,125 cal/g), and small starved (13.2% and 799 cal/g) fish. Lake herring that died during the experiment had significantly lower body condition and energy stores relative to those of the surviving fish. These results suggest that the depletion of energy stores contributes to greater winter mortality of small lake herring with limited energy uptake and may partially explain the variability in recruitment observed in Lake Superior.

  18. Utility of the "Surprise" Question in Predicting Survival among Older Patients with Acute Surgical Conditions.

    Science.gov (United States)

    Lilley, Elizabeth J; Gemunden, Sean A; Kristo, Gentian; Changoor, Navin; Scott, John W; Rickerson, Elizabeth; Shimizu, Naomi; Salim, Ali; Cooper, Zara

    2017-04-01

    The surprise question is a validated tool for identifying patients with increased risk of death within one year who could, therefore, benefit from palliative care. However, its utility in surgery is unknown. We sought to determine whether the surprise question predicted 12-month mortality in older emergency general surgery patients. This was a prospective cohort study. Emergency general surgery attendings and surgical residents in or beyond their third year of training at a single tertiary care academic hospital from January to July 2014. Surgeons responded to the surprise question within 72 hours of evaluating patients, ≥65 years, hospitalized with an acute surgical condition. Patient data, including demographic and clinical characteristics, were extracted from the medical record. Mortality within 12 months of initial evaluation was determined by using Social Security death data. Ten attending surgeons and 18 surgical residents provided 163 responses to the surprise question for 119 patients: 60% of responses were "No, I would not be surprised" and 40% were "Yes, I would be surprised." A "No" response was associated with increased odds of death within 12 months in binary logistic regression (OR 4.8 [95% CI 2.1-11.1]). The surprise question is a valuable tool for identifying older patients with higher risk of death, and it may be a useful screening criterion for older emergency general surgery patients who would benefit from palliative care evaluation.

  19. Survival of Ucides cordatus (Decapoda: Ocypodidae megalopae during transport under different conditions of density and duration

    Directory of Open Access Journals (Sweden)

    Robson Ventura

    2010-01-01

    Full Text Available Target areas for Ucides cordatus (Linnaeus, 1763 restocking programs are often located far from the laboratory where larval rearing is developed. During translocation, the larvae are submitted to highly stressful conditions due to handling, packing, and transport activities. The aim of the present study was to assess the mortality rates of U. cordatus megalopae caused by different transportation procedures. Megalopae at loading densities of 50, 150, and 300 ind.L-1 were packed in double polyethylene 12 x 25 cm plastic bags with 200 ml of marine water at salinity 30. The bags were filled with oxygen at a proportion of 1:2 parts of water and sealed tightly. The trepidations during transport were simulated by the use of a shaker device (800 vibrations/minute over periods of three and six hours inside a dark container. The survivorship rates of larvae after simulation were compared to those obtained in control groups, which consisted of plastic vials with megalopae at a loading density of 50 ind.L-1 maintained at rest. Immediately after the two transport simulations, there was no significant difference in survivorship between the treatments and the control. However, 24 hours after simulation some of the tested densities resulted in significantly lower survivorships. The results demonstrated that U. cordatus megalopae can tolerate six hours of shaking during transportation, at high densities with minimal mortality.

  20. Conditional Survival: An Assessment of the Prognosis of Patients at Time Points After Initial Diagnosis and Treatment of Locoregional Melanoma Metastasis.

    Science.gov (United States)

    Haydu, Lauren E; Scolyer, Richard A; Lo, Serigne; Quinn, Michael J; Saw, Robyn P M; Shannon, Kerwin F; Spillane, Andrew J; Stretch, Jonathan R; McCarthy, William H; Thompson, John F

    2017-05-20

    Purpose Standard cancer staging and prognostic estimates are determined at the time of the patient's initial disease presentation. Conditional survival is an alternative, dynamic assessment from follow-up time points after the initial disease diagnosis and is based on the condition of survivorship. Estimates of conditional survival can provide critical prognostic information for patients and clinicians, guide subsequent cancer follow-up schedules, and influence decisions regarding treatments. The current study presents conditional survival estimates developed from a cohort of 4,540 patients diagnosed with stage III melanoma treated at a single institution. Methods Patients with stage III disease at first melanoma diagnosis (initial; n = 2,042), or who developed locoregional metastasis as a first recurrence some time after primary diagnosis (recurrent; n = 2,498), were assessed. Conditional melanoma-specific survival (MSS) estimates up to 5 years after diagnosis were adjusted for age, sex, and 8th edition American Joint Committee on Cancer (AJCC) stage. Results Older age at diagnosis of stage III disease conveyed a worse prognosis at each conditional survival time point. Males had significantly worse MSS outcomes for up to 2 years of conditional survival, after which males and females had similar MSS. For patients with AJCC stage IIIB and stage IIIC disease, MSS outcomes were similar to those of patients with stage IIIA disease after 3 and 5 years of survivorship, respectively. Conclusion Adjuvant systemic treatments may have the greatest benefit when administered within the first 2 years of stage III melanoma diagnosis, during which period prognosis is significantly worse for male patients of increasing age and AJCC substage. Conditional survival estimates illustrate improved survival prospects for patients with cancer returning for follow-up and may define a finite period of increased risk after diagnosis.

  1. Complex layered dental restorations: Are they recognizable and do they survive extreme conditions?

    Science.gov (United States)

    Soon, Alistair S; Bush, Mary A; Bush, Peter J

    2015-09-01

    Recent research has shown that restorative dental materials can be recognized by microscopy and elemental analysis (scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray fluorescence; SEM/EDS and XRF) and that this is possible even in extreme conditions, such as cremation. These analytical methods and databases of dental materials properties have proven useful in DVI (disaster victim identification) of a commercial plane crash in 2009, and in a number of other victim identification cases. Dental materials appear on the market with ever expanding frequency. With their advent, newer methods of restoration have been proposed and adopted in the dental office. Methods might include placing multiple layers of dental materials, where they have different properties including adhesion, viscosity, or working time. These different dental materials include filled adhesives, flowable resins, glass ionomer cements, composite resins, liners and sealants. With possible combinations of different materials in these restorations, the forensic odontologist is now confronted with a new difficulty; how to recognize each individual material. The question might be posed if it is even possible to perform this task. Furthermore, an odontologist might be called upon to identify a victim under difficult circumstances, such as when presented with fragmented or incinerated remains. In these circumstances the ability to identify specific dental materials could assist in the identification of the deceased. Key to use of this information is whether these new materials and methods are detailed in the dental chart. Visual or radiographic inspection may not reveal the presence of a restoration, let alone the possible complex nature of that restoration. This study demonstrates another scientific method in forensic dental identification. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. Mapping the Iron Oxidation State in Martian Meteorites

    Science.gov (United States)

    Martin, A. M.; Treimann, A. H.; Righter, K.

    2017-01-01

    Several types of Martian igneous meteorites have been identified: clinopyroxenites (nakhlites), basaltic shergottites, peridotitic shergottites, dunites (chassignites) and orthopyroxenites [1,2]. In order to constrain the heterogeneity of the Martian mantle and crust, and their evolution through time, numerous studies have been performed on the iron oxidation state of these meteorites [3,4,5,6,7,8,9]. The calculated fO2 values all lie within the FMQ-5 to FMQ+0.5 range (FMQ representing the Fayalite = Magnetite + Quartz buffer); however, discrepancies appear between the various studies, which are either attributed to the choice of the minerals/melts used, or to the precision of the analytical/calculation method. The redox record in volcanic samples is primarily related to the oxidation state in the mantle source(s). However, it is also influenced by several deep processes: melting, crystallization, magma mixing [10], assimilation and degassing [11]. In addition, the oxidation state in Martian meteorites is potentially affected by several surface processes: assimilation of sediment/ crust during lava flowing at Mars' surface, low temperature micro-crystallization [10], weathering at the surface of Mars and low temperature reequilibration, impact processes (i.e. high pressure phase transitions, mechanical mixing, shock degassing and melting), space weathering, and weathering on Earth (at atmospheric conditions different from Mars). Decoding the redox record of Martian meteorites, therefore, requires large-scale quantitative analysis methods, as well as a perfect understanding of oxidation processes.

  3. A streptococcal NRAMP homologue is crucial for the survival of Streptococcus agalactiae under low pH conditions.

    Science.gov (United States)

    Shabayek, Sarah; Bauer, Richard; Mauerer, Stefanie; Mizaikoff, Boris; Spellerberg, Barbara

    2016-05-01

    Streptococcus agalactiae or Group B Streptococcus (GBS) is a commensal bacterium of the human gastrointestinal and urogenital tracts as well as a leading cause of neonatal sepsis, pneumonia and meningitis. Maternal vaginal carriage is the main source for GBS transmission and thus the most important risk factor for neonatal disease. Several studies in eukaryotes identified a group of proteins natural resistance-associated macrophage protein (NRAMP) that function as divalent cation transporters for Fe(2+) and Mn(2+) and confer on macrophages the ability to control replication of bacterial pathogens. Genome sequencing predicted potential NRAMP homologues in several prokaryotes. Here we describe for the first time, a pH-regulated NRAMP Mn(2+) /Fe(2+) transporter in GBS, designated MntH, which confers resistance to reactive oxygen species (ROS) and is crucial for bacterial growth and survival under low pH conditions. Our investigation implicates MntH as an important colonization determinant for GBS in the maternal vagina as it helps bacteria to adapt to the harsh acidic environment, facilitates bacterial adherence, contributes to the coexistence with the vaginal microbiota and plays a role in GBS intracellular survival inside macrophages. © 2016 John Wiley & Sons Ltd.

  4. A comparison of the conditional inference survival forest model to random survival forests based on a simulation study as well as on two applications with time-to-event data.

    Science.gov (United States)

    Nasejje, Justine B; Mwambi, Henry; Dheda, Keertan; Lesosky, Maia

    2017-07-28

    Random survival forest (RSF) models have been identified as alternative methods to the Cox proportional hazards model in analysing time-to-event data. These methods, however, have been criticised for the bias that results from favouring covariates with many split-points and hence conditional inference forests for time-to-event data have been suggested. Conditional inference forests (CIF) are known to correct the bias in RSF models by separating the procedure for the best covariate to split on from that of the best split point search for the selected covariate. In this study, we compare the random survival forest model to the conditional inference model (CIF) using twenty-two simulated time-to-event datasets. We also analysed two real time-to-event datasets. The first dataset is based on the survival of children under-five years of age in Uganda and it consists of categorical covariates with most of them having more than two levels (many split-points). The second dataset is based on the survival of patients with extremely drug resistant tuberculosis (XDR TB) which consists of mainly categorical covariates with two levels (few split-points). The study findings indicate that the conditional inference forest model is superior to random survival forest models in analysing time-to-event data that consists of covariates with many split-points based on the values of the bootstrap cross-validated estimates for integrated Brier scores. However, conditional inference forests perform comparably similar to random survival forests models in analysing time-to-event data consisting of covariates with fewer split-points. Although survival forests are promising methods in analysing time-to-event data, it is important to identify the best forest model for analysis based on the nature of covariates of the dataset in question.

  5. Occurrence of Shewanella algae in Danish coastal water and effects of water temperature and culture conditions on its survival

    DEFF Research Database (Denmark)

    Gram, Lone; Bundvad, Anemone; Melchiorsen, Jette

    1999-01-01

    C. The bacterium is a typical mesophilic organism, and model experiments were conducted to elucidate the fate of the organism under cold and nutrient-limited conditions. The culturable count of S. algae decreased rapidly from 10(7) CFU/ml to 10(1) CFU/ml in approximately 1 month when cells grown...... at 20 to 37 degrees C were exposed to cold (2 degrees C) seawater. In contrast, the culturable count of cells exposed to warmer seawater (10 to 25 degrees C) remained constant. Allowing the bacterium a transition period in seawater at 20 degrees C before exposure-to the 2 degrees C seawater resulted...... in 100% survival over a period of 1 to 2 months. The cold protection offered by this transition (starvation) probably explains the ability of the organism to persist in Danish seawater despite very low (0 to 1 degrees C) winter water temperatures. The culturable counts of samples kept at 2 degrees C...

  6. Testing the water hypothesis: Quantitative morphological analysis of terrestrial and martian mid-latitude gullies

    Science.gov (United States)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.

    2017-10-01

    Although Martian gullies resemble terrestrial counterparts, two conflicting hypotheses exist for their formation still invoke fluvial processes on the one hand or lubricated CO2 flows on the other. In this work we compared the quantitative morphology of terrestrial gullies, known to have formed by liquid water, and mid-latitude Martian gullies in the Martian southern hemisphere. We also compared these results with measurements of Martian dry ravines adjacent to the gullies. Our results show a similarity between Martian and terrestrial gully formation, supporting the hypothesis that liquid water was involved in their erosion. Our results show dry ravines differ morphologically from gullies, further suggesting fluidised flows as a likely origin of the latter. Variations in the relationships across various terrestrial and Martian gullies indicate the significance of local environmental and geological conditions. Our work supports the idea that Martian gullies may not have been formed by just one single process but may have evolved through a more complex interaction of processes and environment.

  7. Physical and chemical properties of the Martian soil: Review of resources

    Science.gov (United States)

    Stoker, C. R.; Gooding, James L.; Banin, A.; Clark, Benton C.; Roush, Ted

    1991-01-01

    The chemical and physical properties of Martian surface materials are reviewed from the perspective of using these resources to support human settlement. The resource potential of Martian sediments and soils can only be inferred from limited analyses performed by the Viking Landers (VL), from information derived from remote sensing, and from analysis of the SNC meteorites thought to be from Mars. Bulk elemental compositions by the VL inorganic chemical (x ray fluorescence) analysis experiments have been interpreted as evidence for clay minerals (possibly smectites) or mineraloids (palagonite) admixed with sulfate and chloride salts. The materials contained minerals bearing Fe, Ti, Al, Mg and Si. Martian surface materials may be used in many ways. Martian soil, with appropriate preconditioning, can probably be used as a plant growth medium, supplying mechanical support, nutrient elements, and water at optimal conditions to the plants. Loose Martian soils could be used to cover structures and provide radiation shielding for surface habitats. Martian soil could be wetted and formed into abode bricks used for construction. Duricrete bricks, with strength comparable to concrete, can probably be formed using compressed muds made from martian soil.

  8. Importance of mitochondria in survival of Cryptococcus neoformans under low oxygen conditions and tolerance to cobalt chloride.

    Directory of Open Access Journals (Sweden)

    Susham S Ingavale

    2008-09-01

    Full Text Available Cryptococcus neoformans is an environmental fungal pathogen that requires atmospheric levels of oxygen for optimal growth. For the fungus to be able to establish an infection, it must adapt to the low oxygen concentrations in the host environment compared to its natural habitat. In order to investigate the oxygen sensing mechanism in C. neoformans, we screened T-DNA insertional mutants for hypoxia-mimetic cobalt chloride (CoCl(2-sensitive mutants. All the CoCl(2-sensitive mutants had a growth defect under low oxygen conditions at 37 degrees C. The majority of mutants are compromised in their mitochondrial function, which is reflected by their reduced rate of respiration. Some of the mutants are also defective in mitochondrial membrane permeability, suggesting the importance of an intact respiratory system for survival under both high concentrations of CoCl(2 as well as low oxygen conditions. In addition, the mutants tend to accumulate intracellular reactive oxygen species (ROS, and all mutants show sensitivity to various ROS generating chemicals. Gene expression analysis revealed the involvement of several pathways in response to cobalt chloride. Our findings indicate cobalt chloride sensitivity and/or sensitivity to low oxygen conditions are linked to mitochondrial function, sterol and iron homeostasis, ubiquitination, and the ability of cells to respond to ROS. These findings imply that multiple pathways are involved in oxygen sensing in C. neoformans.

  9. Resistance of Terrestrial Microbial Communities to Impack of Physical Conditinos of Subsurface Layers of Martian Regolith

    Science.gov (United States)

    Cheptsov, V. S.; Vorobyova, E. A.

    2017-05-01

    Currently, astrobiology is focused on Mars as one of the most perspective objects in the Solar System to search for microbial life. It was assumed that the putative biosphere of Mars could be cryopreserved and had been stored for billions of years in anabiotic state like microbial communities of Arctic and Antarctic permafrost deposits have been preserved till now for millions of years. In this case microbial cells should be not able to repair the damages or these processes have to be significantly depressed, and the main factor causing cell's death should be ionizing radiation. In a series of experiments we simulated the effects of combination of physical factors known as characteristics of the Martian regolith (and close to the space environment) on the natural microbial communities inhabiting xerophytic harsh habitats with extreme temperature conditions: polar permafrost and desert soils. The aim of the study was to examine the cumulative effect of factors (gamma radiation, low temperature, low pressure) to assess the possibility of metabolic reactions, and to find limits of the viability of natural microbial communities after exposure to the given conditions. It was found that microbial biomarkers could be reliably detected in soil samples after radiation dose accumulation up to 1 MGy (not further investigated) in combination with exposure to low temperature and low pressure. Resistance to extremely high doses of radiation in simulated conditions proves that if there was an Earth-like biosphere on the early Mars microorganisms could survive in the surface or subsurface layers of the Martian regolith for more than tens of millions of years after climate change. The study gives also some new grounds for the approval of transfer of viable microorganisms in space.

  10. Evolution of the martian mantle as recorded by igneous rocks

    Science.gov (United States)

    Balta, J. B.; McSween, H. Y.

    2013-12-01

    explain the decreasing silica contents measured in the young volcanoes and thus fits the measurements from the surface, and producing the high-silica shergottites through a thick crust is difficult without the presence of water. Our model requires that, after differentiation, the martian mantle retained significant water. Much of that water was released early in Mars's history as widespread volcanism allowed for initial dehydration of much of the mantle. The more recent volcanism involved in building the large surface volcanoes was then produced largely from the melting of previously-dehydrated mantle, with possible contributions from crustal rocks and fluids rich in volatiles such as Cl or CO2. Rocks such as the Gusev basalts and the nakhlite and chassignite meteorites also fit into this model and do not require unique circumstances such as a highly-oxidized early martian atmosphere or mantle. Finally, the magmas that eventually became the shergottites were produced when surviving hydrous mantle, similar to that which produced ALH 84001, was entrained in a mantle upwelling such as Tharsis. 1 Nyquist, L. E. et al.. GCA 73, 4288-4309 (2009). 2 Lapen, T. J. et al.. Science 328, 347-351, (2010).

  11. Mapping and analysis of Martian landslides

    Science.gov (United States)

    Crosta, Giovanni B.; Frattini, Paolo; Valbuzzi, Elena; Russo, Valeria

    2013-04-01

    This work is part of a larger effort aimed to a more quantitative description of landslide phenomena on Mars and the understanding of rock mass properties and landslide mobility with respect to their Earth equivalents. Recently, large satellite imagery datasets have become available and they have been mosaicked in different suitable tools making mapping an easier job than before. Furthermore, the availability of other georeferenced database makes possible and easily feasible some spatially distributed analyses. We prepared a new landslide inventory to acquire information about: landslide size distribution and areal density, controls of geometrical condition along Martian slopes, landslide typology and mechanism, relationship with impact craters distribution, runout, volume estimates, characteristic features. We adopted Google Earth, Google, Inc. as a mapping tool using both visible and CTX images. Landslides have been mapped according to standard geomorphological criteria, by two landslide experts delineating both the landslide scar and accumulation limits, associating each scarp to a deposit. Multiple accumulations have been differentiated where possible to obtain a more sound dataset. We prevalently mapped landslides located along the Martian valleys and Chasma flanks with only minor attention to classical block and slump instabilities typical of crater rim failures. This because we were mainly interested in long runout landslides or complex failures which could allow to define some rock mass characteristics along these slopes, and to study landslide mobility with respect to Earth equivalent phenomena. So long runout landslides have been mapped also when recognized within crater rims. Topographic characteristics have been extracted by means of the available MOLA dataset. The inventory presently consists of 1232 landslides covering a total area of about 180,000 km2. Landslide size ranges from 0.15 km2 to a maximum of 12,000 km2. We examined area

  12. Identification and Characterization of Early Mission Phase Microorganisms Residing on the Mars Science Laboratory and Assessment of Their Potential to Survive Mars-like Conditions.

    Science.gov (United States)

    Smith, Stephanie A; Benardini, James N; Anderl, David; Ford, Matt; Wear, Emmaleen; Schrader, Michael; Schubert, Wayne; DeVeaux, Linda; Paszczynski, Andrzej; Childers, Susan E

    2017-03-01

    Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to survive and grow on Mars. Having this knowledge is paramount to addressing whether microorganisms transported from Earth could negatively impact future space exploration. The objectives of this study were to identify cultivable microorganisms collected from the surface of the Mars Science Laboratory, to distinguish which of the cultivable microorganisms can utilize energy sources potentially available on Mars, and to determine the survival of the cultivable microorganisms upon exposure to physiological stresses present on the martian surface. Approximately 66% (237) of the 358 microorganisms identified are related to members of the Bacillus genus, although surprisingly, 22% of all isolates belong to non-spore-forming genera. A small number could grow by reduction of potential growth substrates found on Mars, such as perchlorate and sulfate, and many were resistant to desiccation and ultraviolet radiation (UVC). While most isolates either grew in media containing ≥10% NaCl or at 4°C, many grew when multiple physiological stresses were applied. The study yields details about the microorganisms that inhabit the surfaces of spacecraft after microbial reduction measures, information that will help gauge whether microorganisms from Earth pose a forward contamination risk that could impact future planetary protection policy. Key Words: Planetary protection-Spore-Bioburden-MSL-Curiosity-Contamination-Mars. Astrobiology 17, 253-265.

  13. Effects of acidifying ocean conditions on growth and survival of two life stages of the blue crab, Callinectes sapidus.

    Science.gov (United States)

    Giltz, S.; Taylor, C.

    2016-02-01

    Blue crabs, Callinectes sapidus, begin their larval phase offshore and circulate for approximately 30 days before settling near shore. As crabs transition to the juvenile stage, they move into coastal or estuarine environments characterized by lower salinity. Presently the average pH of the ocean is 8.1, 30% down from the beginning of the industrial revolution and is forecasted to drop to 7.8 by 2100. Decreasing pH causes dissolution of calcium carbonate shells, but the overall effects on crustaceans, such as blue crabs, are unknown. This study investigated the effect of a lower pH environment on the growth, survival, carapace hardness and molt frequency of larval and juvenile blue crabs in the Northern Gulf of Mexico. Larval crabs showed delayed growth under low pH (7.8) conditions compared to crabs in a control (present day) pH (8.1) environment. Population crashes (complete mortality) were experienced in 55% of the low pH aquaria but not in any of the control aquaria, suggesting that acidification poses a mortality risk. Under low pH conditions the intermolt duration decreased in juveniles, but the body length and weight did not differ from crabs raised in the control pH. Larvae (in tanks that did not crash) and juveniles did not experience increased mortality from a lower pH, but there do appear to be sublethal effects on growth and molting that differ between life history stages.

  14. Conditional inactivation of MRG15 gene function limits survival during larval and adult stages of Drosophila melanogaster.

    Science.gov (United States)

    Zhang, Hongjun; Li, Yishi; Yang, Junsheng; Tominaga, Kaoru; Pereira-Smith, Olivia M; Tower, John

    2010-11-01

    The mammalian MRG15 gene encodes a chromodomain protein predicted to bind to chromatin via methylated histone tails. Human MORF4 encodes a related but truncated protein that is capable of promoting cellular senescence in a subset of human tumor cell lines. Drosophila contains a single homolog of human MRG15, called DmMRG15. Null mutation of MRG15 is embryonic-lethal in mice and Drosophila, making the study of MRG15 requirements in adults difficult. In these studies the DmMRG15 gene was over-expressed in Drosophila, during developmental stages and in adults, using a doxycycline-regulated system (Tet-on). In addition an inverted-repeated construct was designed to inactivate DmMRG15 via the RNAi pathway, and RNAi constructs were expressed using both the Tet-on system and Geneswitch system. The DmMRG15 protein was readily expressed in adult flies in a doxycycline-dependent manner. A truncated form of DmMRG15 (called DmMT1) was designed to mimic the structure of human MORF4, and expression of this mutant protein or the inverted-repeat constructs inhibited fertility in females. Conditional expression of the DmMRG15 inverted-repeat constructs during larval development or in adults caused reductions in survival. These experiments indicate that Drosophila DmMRG15 gene function is required for female fertility, larval survival and adult life span, and provide reagents that should be useful for further dissecting the role of DmMRG15 in cell proliferation and aging. Copyright © 2010 Elsevier Inc. All rights reserved.

  15. Effect of Microencapsulation on Survival and Stability of Bifidobacterium bifidum BB01 Exposed to Simulated Gastrointestinal Conditions and in Different Food Matrices

    OpenAIRE

    Chen He; Ma Donglin; Li Yichao; Liu Yu; Wang Ye

    2017-01-01

    Bifidobacterium bifidum BB01 was microencapsulated by extrusion method with sodium alginate. This paper aimed to study the survival rate of microencapsulating Bifidobacterium bifidum BB01 in simulated gastrointestinal conditions, resistance to artificial bile salt and stability during storage. Results showed non-microencapsulated Bifidobacterium bifidum BB01 were more susceptible than microencapsulated under simulated gastrointestinal conditions, and microencapsulated Bifidobacterium bifidum ...

  16. Comparison of survival patterns of northern and southern genotypes of the North American tick Ixodes scapularis (Acari: Ixodidae) under northern and southern conditions.

    Science.gov (United States)

    Ginsberg, Howard S; Rulison, Eric L; Azevedo, Alexandra; Pang, Genevieve C; Kuczaj, Isis M; Tsao, Jean I; LeBrun, Roger A

    2014-08-26

    Several investigators have reported genetic differences between northern and southern populations of Ixodes scapularis in North America, as well as differences in patterns of disease transmission. Ecological and behavioral correlates of these genetic differences, which might have implications for disease transmission, have not been reported. We compared survival of northern with that of southern genotypes under both northern and southern environmental conditions in laboratory trials. Subadult I. scapularis from laboratory colonies that originated from adults collected from deer from several sites in the northeastern, north central, and southern U.S. were exposed to controlled conditions in environmental chambers. Northern and southern genotypes were exposed to light:dark and temperature conditions of northern and southern sites with controlled relative humidities, and mortality through time was recorded. Ticks from different geographical locations differed in survival patterns, with larvae from Wisconsin surviving longer than larvae from Massachusetts, South Carolina or Georgia, when held under the same conditions. In another experiment, larvae from Florida survived longer than larvae from Michigan. Therefore, survival patterns of regional genotypes did not follow a simple north-south gradient. The most consistent result was that larvae from all locations generally survived longer under northern conditions than under southern conditions. Our results suggest that conditions in southern North America are less hospitable than in the north to populations of I. scapularis. Southern conditions might have resulted in ecological or behavioral adaptations that contribute to the relative rarity of I. scapularis borne diseases, such as Lyme borreliosis, in the southern compared to the northern United States.

  17. Comparison of survival patterns of northern and southern genotypes of the North American tick Ixodes scapularis (Acari: Ixodidae) under northern and southern conditions

    Science.gov (United States)

    Ginsberg, Howard S.; Rulison, Eric L.; Azevedo, Alexandra; Pang, Genevieve C.; Kuczaj, Isis M.; Tsao, Jean I.; LeBrun, Roger A.

    2014-01-01

    BackgroundSeveral investigators have reported genetic differences between northern and southern populations of Ixodes scapularis in North America, as well as differences in patterns of disease transmission. Ecological and behavioral correlates of these genetic differences, which might have implications for disease transmission, have not been reported. We compared survival of northern with that of southern genotypes under both northern and southern environmental conditions in laboratory trials.MethodsSubadult I. scapularis from laboratory colonies that originated from adults collected from deer from several sites in the northeastern, north central, and southern U.S. were exposed to controlled conditions in environmental chambers. Northern and southern genotypes were exposed to light:dark and temperature conditions of northern and southern sites with controlled relative humidities, and mortality through time was recorded.ResultsTicks from different geographical locations differed in survival patterns, with larvae from Wisconsin surviving longer than larvae from Massachusetts, South Carolina or Georgia, when held under the same conditions. In another experiment, larvae from Florida survived longer than larvae from Michigan. Therefore, survival patterns of regional genotypes did not follow a simple north–south gradient. The most consistent result was that larvae from all locations generally survived longer under northern conditions than under southern conditions.ConclusionsOur results suggest that conditions in southern North America are less hospitable than in the north to populations of I. scapularis. Southern conditions might have resulted in ecological or behavioral adaptations that contribute to the relative rarity of I. scapularis borne diseases, such as Lyme borreliosis, in the southern compared to the northern United States.

  18. JMSS-1: a new Martian soil simulant

    Science.gov (United States)

    Zeng, Xiaojia; Li, Xiongyao; Wang, Shijie; Li, Shijie; Spring, Nicole; Tang, Hong; Li, Yang; Feng, Junming

    2015-05-01

    It is important to develop Martian soil simulants that can be used in Mars exploration programs and Mars research. A new Martian soil simulant, called Jining Martian Soil Simulant (JMSS-1), was developed at the Lunar and Planetary Science Research Center at the Institute of Geochemistry, Chinese Academy of Sciences. The raw materials of JMSS-1 are Jining basalt and Fe oxides (magnetite and hematite). JMSS-1 was produced by mechanically crushing Jining basalt with the addition of small amounts of magnetite and hematite. The properties of this simulant, including chemical composition, mineralogy, particle size, mechanical properties, reflectance spectra, dielectric properties, volatile content, and hygroscopicity, have been analyzed. On the basis of these test results, it was demonstrated that JMSS-1 is an ideal Martian soil simulant in terms of chemical composition, mineralogy, and physical properties. JMSS-1 would be an appropriate choice as a Martian soil simulant in scientific and engineering experiments in China's Mars exploration in the future.

  19. Diversity of Survival Patterns among Escherichia coli O157:H7 Genotypes Subjected to Food-Related Stress Conditions.

    Science.gov (United States)

    Elhadidy, Mohamed; Álvarez-Ordóñez, Avelino

    2016-01-01

    The purpose of this study was to evaluate the resistance patterns to food-related stresses of Shiga toxin producing Escherichia coli O157:H7 strains belonging to specific genotypes. A total of 33 E. coli O157:H7 strains were exposed to seven different stress conditions acting as potential selective pressures affecting the transmission of E. coli O157:H7 to humans through the food chain. These stress conditions included cold, oxidative, osmotic, acid, heat, freeze-thaw, and starvation stresses. The genotypes used for comparison included lineage-specific polymorphism, Shiga-toxin-encoding bacteriophage insertion sites, clade type, tir (A255T) polymorphism, Shiga toxin 2 subtype, and antiterminator Q gene allele. Bacterial resistance to different stressors was calculated by determining D-values (times required for inactivation of 90% of the bacterial population), which were then subjected to univariate and multivariate analyses. In addition, a relative stress resistance value, integrating resistance values to all tested stressors, was calculated for each bacterial strain and allowed for a ranking-type classification of E. coli O157:H7 strains according to their environmental robustness. Lineage I/II strains were found to be significantly more resistant to acid, cold, and starvation stress than lineage II strains. Similarly, tir (255T) and clade 8 encoding strains were significantly more resistant to acid, heat, cold, and starvation stress than tir (255A) and non-clade 8 strains. Principal component analysis, which allows grouping of strains with similar stress survival characteristics, separated strains of lineage I and I/II from strains of lineage II, which in general showed reduced survival abilities. Results obtained suggest that lineage I/II, tir (255T), and clade 8 strains, which have been previously reported to be more frequently associated with human disease cases, have greater multiple stress resistance than strains of other genotypes. The results from this

  20. The Northwest Africa 8159 martian meteorite: Expanding the martian sample suite to the early Amazonian

    Science.gov (United States)

    Herd, Christopher D. K.; Walton, Erin L.; Agee, Carl B.; Muttik, Nele; Ziegler, Karen; Shearer, Charles K.; Bell, Aaron S.; Santos, Alison R.; Burger, Paul V.; Simon, Justin I.; Tappa, Michael J.; McCubbin, Francis M.; Gattacceca, Jérôme; Lagroix, France; Sanborn, Matthew E.; Yin, Qing-Zhu; Cassata, William S.; Borg, Lars E.; Lindvall, Rachel E.; Kruijer, Thomas S.; Brennecka, Gregory A.; Kleine, Thorsten; Nishiizumi, Kunihiko; Caffee, Marc W.

    2017-12-01

    Northwest Africa (NWA) 8159 is an augite-rich shergottite, with a mineralogy dominated by Ca-, Fe-rich pyroxene, plagioclase, olivine, and magnetite. NWA 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling, likely in a surface lava flow or shallow sill. Redox conditions experienced by the melt shifted from relatively oxidizing (with respect to known Martian lithologies, ∼QFM) on the liquidus to higher oxygen fugacity (∼QFM + 2) during crystallization of the groundmass, and under subsolidus conditions. This shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims. NWA 8159 contains both crystalline and shock-amorphized plagioclase (An50-62), often observed within a single grain; based on known calibrations we bracket the peak shock pressure experienced by NWA 8159 to between 15 and 23 GPa. The bulk composition of NWA 8159 is depleted in LREE, as observed for Tissint and other depleted shergottites; however, NWA 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity. We obtain a Sm-Nd formation age of 2.37 ± 0.25 Ga for NWA 8159, which represents an interval in Mars geologic time which, until recently, was not represented in the other martian meteorite types. The bulk rock 147Sm/144Nd value of 0.37 ± 0.02 is consistent with it being derived directly from its source and the high initial ε143Nd value indicates this source was geochemically highly depleted. Cr, Nd, and W isotopic compositions further support a unique mantle source. While the rock shares similarities with the 2.4-Ga NWA 7635 meteorite, there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization. Nevertheless, the two samples may be launch-paired. NWA 8159 expands the known basalt types, ages and mantle sources within the Mars sample suite to include a second igneous unit from

  1. Effect of Brood Pheromone on Survival and Nutrient Intake of African Honey Bees (Apis mellifera scutellata) under Controlled Conditions.

    Science.gov (United States)

    Démares, Fabien J; Yusuf, Abdullahi A; Nicolson, Susan W; Pirk, Christian W W

    2017-05-01

    The influence of pheromones on insect physiology and behavior has been thoroughly reported for numerous aspects, such as attraction, gland development, aggregation, mate and kin recognition. Brood pheromone (BP) is released by honey bee larvae to indicate their protein requirements to the colony. Although BP is known to modulate pollen and protein consumption, which in turn can affect physiological and morphological parameters, such as hypopharyngeal gland (HPG) development and ovarian activation, few studies have focused on the effect of BP on nutritional balance. In this study, we exposed newly emerged worker bees for 14 d and found that BP exposure increased protein intake during the first few days, with a peak in consumption at day four following exposure. BP exposure decreased survival of caged honey bees, but did not affect either the size of the HPG acini or ovarian activation stage. The uncoupling of the BP releaser effect, facilitated by working under controlled conditions, and the presence of larvae as stimulating cues are discussed.

  2. Survival of the fittest clone: Pro-apoptotic protein Noxa controls selection of lymphocytes under competitive conditions

    NARCIS (Netherlands)

    Wensveen, F.M.

    2010-01-01

    Darwinistic selection, or ‘survival of the fittest’, is based on intrinsic capacity, relative to that of its competitors in a given niche. This process drives the generation of species by allowing survival of organisms in with favorable, specialized characteristics for a certain niche. However, mere

  3. Effects of dairy manure storage conditions on the survival of E. coli O157:H7 and listeria

    Science.gov (United States)

    Dairy manure is regularly applied to crop fields as a solid or liquid to improve the soil nutrient status. However, pathogens may survive during manure storage and enter the environment during application. In this study, three storage practices were evaluated to understand the survival patterns of E...

  4. A model of Martian surface chemistry

    Science.gov (United States)

    Oyama, V. I.; Berdahl, B. J.

    1979-01-01

    Alkaline earth and alkali metal superoxides and peroxides, gamma-Fe2O3 and carbon suboxide polymer, are proposed to be constituents of the Martian surface material. These reactive substances explain the water modified reactions and thermal behaviors of the Martian samples demonstrated by all of the Viking Biology Experiments. It is also proposed that the syntheses of these substances result mainly from electrical discharges between wind-mobilized particles at Martian pressures; plasmas are initiated and maintained by these discharges. Active species in the plasma either combine to form or react with inorganic surfaces to create the reactive constituents.

  5. On the Effect of Planetary Stable Isotope Compositions on Growth and Survival of Terrestrial Organisms.

    Directory of Open Access Journals (Sweden)

    Xueshu Xie

    Full Text Available Isotopic compositions of reactants affect the rates of chemical and biochemical reactions. Usually it is assumed that heavy stable isotope enrichment leads to progressively slower reactions. Yet the effect of stable isotopes may be nonlinear, as exemplified by the "isotopic resonance" phenomenon. Since the isotopic compositions of other planets of Solar system, including Mars and Venus, are markedly different from terrestrial (e.g., deuterium content is ≈5 and ≈100 times higher, respectively, it is far from certain that terrestrial life will thrive in these isotopic conditions. Here we found that Martian deuterium content negatively affected survival of shrimp in semi-closed biosphere on a year-long time scale. Moreover, the bacterium Escherichia coli grows slower at Martian isotopic compositions and even slower at Venus's compositions. Thus, the biological impact of varying stable isotope compositions needs to be taken into account when planning interplanetary missions.

  6. On the Effect of Planetary Stable Isotope Compositions on Growth and Survival of Terrestrial Organisms.

    Science.gov (United States)

    Xie, Xueshu; Zubarev, Roman A

    2017-01-01

    Isotopic compositions of reactants affect the rates of chemical and biochemical reactions. Usually it is assumed that heavy stable isotope enrichment leads to progressively slower reactions. Yet the effect of stable isotopes may be nonlinear, as exemplified by the "isotopic resonance" phenomenon. Since the isotopic compositions of other planets of Solar system, including Mars and Venus, are markedly different from terrestrial (e.g., deuterium content is ≈5 and ≈100 times higher, respectively), it is far from certain that terrestrial life will thrive in these isotopic conditions. Here we found that Martian deuterium content negatively affected survival of shrimp in semi-closed biosphere on a year-long time scale. Moreover, the bacterium Escherichia coli grows slower at Martian isotopic compositions and even slower at Venus's compositions. Thus, the biological impact of varying stable isotope compositions needs to be taken into account when planning interplanetary missions.

  7. Potential Antifreeze Compounds in Present-Day Martian Seepage Groundwater

    Directory of Open Access Journals (Sweden)

    Jiin-Shuh Jean

    2008-01-01

    Full Text Available Is the recently found seepage groundwater on Mars pure H2O, or mixed with salts and other antifreeze compounds? Given the surface conditions of Mars, it is unlikely that pure water could either exist in its liquid state or have shaped Mars¡¦ fluid erosional landforms (gullies, channels, and valley networks. More likely is that Mars¡¦ seepage groundwater contains antifreeze and salt compounds that resist freezing and suppress evaporation. This model better accounts for Mars¡¦ enigmatic surface erosion. This paper suggests 17 antifreeze compounds potentially present in Martian seepage groundwater. Given their liquid state and physical properties, triethylene glycol, diethylene glycol, ethylene glycol, and 1,3-propylene glycol are advanced as the most likely candidate compounds. This paper also explores how a mixing of glycol or glycerol with salts in the Martian seepage groundwater may have lowered water¡¦s freezing point and raised its boiling point, with consequences that created fluid gully and channel erosion. Ethylene glycol and related hydrocarbon compounds have been identified in Martian and other interstellar meteorites. We suggest that these compounds and their proportions to water be included for detection in future explorations.

  8. Meteorite constraints on Martian atmospheric loss and paleoclimate

    Science.gov (United States)

    Cassata, William S.

    2017-12-01

    The evolution of Mars' atmosphere to its currently thin state incapable of supporting liquid water remains poorly understood and has important implications for Martian climate history. Martian meteorites contain trapped atmospheric gases that can be used to constrain both the timing and effectiveness of atmospheric escape processes. In this paper, measurements of xenon isotopes in two ancient Martian meteorites, ALH 84001 and NWA 7034, are reported. The data indicate an early episode of atmospheric escape that mass fractionated xenon isotopes culminated within a few hundred million years of planetary formation, and little change to the atmospheric xenon isotopic composition has occurred since this time. In contrast, on Earth atmospheric xenon fractionation continued for at least two billion years (Pujol et al., 2011). Such differences in atmospheric Xe fractionation between the two planets suggest that climate conditions on Mars may have differed significantly from those on Archean Earth. For example, the hydrogen escape flux may not have exceeded the threshold required for xenon escape on Mars after 4.2-4.3 Ga, which indicates that Mars may have been significantly drier than Earth after this time.

  9. Changes in the Martian atmosphere induced by auroral electron precipitation

    Science.gov (United States)

    Shematovich, V. I.; Bisikalo, D. V.; Gérard, J.-C.; Hubert, B.

    2017-09-01

    Typical auroral events in the Martian atmosphere, such as discrete and diffuse auroral emissions detected by UV spectrometers onboard ESA Mars Express and NASA MAVEN, are investigated. Auroral electron kinetic energy distribution functions and energy spectra of the upward and downward electron fluxes are obtained by electron transport calculations using the kinetic Monte Carlo model. These characteristics of auroral electron fluxes make it possible to calculate both the precipitation-induced changes in the atmosphere and the observed manifestations of auroral events on Mars. In particular, intensities of discrete and diffuse auroral emissions in the UV and visible wavelength ranges (Soret et al., 2016; Bisikalo et al., 2017; Gérard et al., 2017). For these conditions of auroral events, the analysis is carried out, and the contribution of the fluxes of precipitating electrons to the heating and ionization of the Martian atmosphere is estimated. Numerical calculations show that in the case of discrete auroral events the effect of the residual crustal magnetic field leads to a significant increase in the upward fluxes of electrons, which causes a decrease in the rates of heating and ionization of the atmospheric gas in comparison with the calculations without taking into account the residual magnetic field. It is shown that all the above-mentioned impact factors of auroral electron precipitation processes should be taken into account both in the photochemical models of the Martian atmosphere and in the interpretation of observations of the chemical composition and its variations using the ACS instrument onboard ExoMars.

  10. Martian Length of Day Measurements from Rovers

    Science.gov (United States)

    Eubanks, T. M.; Bills, B.

    2012-06-01

    Changes in the Martian Length of Day (LOD) can be determined at a scientifically use level by a combination of regular (but not necessarily frequent) range and Doppler measurements from Earth and dead reckoning in a Kalman filter.

  11. Magnesium Based Rockets for Martian Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In the proposed Phase II program, we will continue the development of Mg bipropellant rockets for Martian PAV applications. In Phase I, we proved the feasibility of...

  12. Osteoinduction and survival of osteoblasts and bone-marrow stromal cells in 3D biphasic calcium phosphate scaffolds under static and dynamic culture conditions

    OpenAIRE

    Rath, Subha N; Strobel, Leonie A; Arkudas, Andreas; Beier, Justus P; Maier, Anne-Kathrin; Greil, Peter; Horch, Raymund E; Kneser, Ulrich

    2012-01-01

    In many tissue engineering approaches, the basic difference between in vitro and in vivo conditions for cells within three-dimensional (3D) constructs is the nutrition flow dynamics. To achieve comparable results in vitro, bioreactors are advised for improved cell survival, as they are able to provide a controlled flow through the scaffold. We hypothesize that a bioreactor would enhance long-term differentiation conditions of osteogenic cells in 3D scaffolds. To achieve this either primary ra...

  13. Optically stimulated luminescence dating properties of Martian sediment analogue materials exposed to a simulated Martian solar spectral environment

    Energy Technology Data Exchange (ETDEWEB)

    Detschel, M.J. [Department of Physics, North Dakota State University, 218 South Engineering, Fargo, ND 58102 (United States); Department of Geosciences, North Dakota State University, 218 Stevens Hall, Fargo, ND 58102 (United States)], E-mail: Marissa.Detschel@ndsu.edu; Lepper, K. [Department of Geosciences, North Dakota State University, 218 Stevens Hall, Fargo, ND 58102 (United States)], E-mail: ken.lepper@ndsu.edu

    2009-04-15

    Deciphering the geomorphic, climatic, and hydrologic history of Mars will require an extensive geochronology on numerous time scales from both returned samples and in-situ measurements. Optically stimulated luminescence dating (OSL), or optical dating, is an established terrestrial geochronological method that is being developed as a member of a suite of dating tools for Mars. As part of this development process, we have built an optical system simulating the calculated Martian solar spectral irradiance taking into account seasonal variations due to attenuation of dust and the planet's orbital position and used it to catalogue the UV dosimetric response and optical dating behavior of a group of sediment analogues exposed to a simulated Martian spectral environment (SMSE) for the surface of the planet. Our results suggest that optical dating should not be compromised by the interaction of the enhanced UV radiation in the Martian spectrum with K-feldspar, Ca-feldspar, anhydrite, or hydrous Ca and Mg sulfates on Mars. However, Na-feldspar appears to be capable of acquiring and retaining an OSL signal under SMSE conditions, which could present a challenge for optical dating on Mars in sedimentary deposits containing more than a trace quantity of sodic feldspars.

  14. Physical condition and stress levels during early development reflect feeding rates and predict pre- and post-fledging survival in a nearshore seabird

    Science.gov (United States)

    Lamb, Juliet S.; O'Reilly, Kathleen M.; Jodice, Patrick G.R.

    2016-01-01

    The effects of acute environmental stressors on reproduction in wildlife are often difficult to measure because of the labour and disturbance involved in collecting accurate reproductive data. Stress hormones represent a promising option for assessing the effects of environmental perturbations on altricial young; however, it is necessary first to establish how stress levels are affected by environmental conditions during development and whether elevated stress results in reduced survival and recruitment rates. In birds, the stress hormone corticosterone is deposited in feathers during the entire period of feather growth, making it an integrated measure of background stress levels during development. We tested the utility of feather corticosterone levels in 3- to 4-week-old nestling brown pelicans (Pelecanus occidentalis) for predicting survival rates at both the individual and colony levels. We also assessed the relationship of feather corticosterone to nestling body condition and rates of energy delivery to nestlings. Chicks with higher body condition and lower corticosterone levels were more likely to fledge and to be resighted after fledging, whereas those with lower body condition and higher corticosterone levels were less likely to fledge or be resighted after fledging. Feather corticosterone was also associated with intracolony differences in survival between ground and elevated nest sites. Colony-wide, mean feather corticosterone predicted nest productivity, chick survival and post-fledging dispersal more effectively than did body condition, although these relationships were strongest before fledglings dispersed away from the colony. Both reproductive success and nestling corticosterone were strongly related to nutritional conditions, particularly meal delivery rates. We conclude that feather corticosterone is a powerful predictor of reproductive success and could provide a useful metric for rapidly assessing the effects of changes in environmental

  15. Martian Bow Shock and Magnetic Pile-Up Barrier Formation Due to the Exosphere Ion Mass-Loading

    Directory of Open Access Journals (Sweden)

    Eojin Kim

    2011-03-01

    Full Text Available Bow shock, formed by the interaction between the solar wind and a planet, is generated in different patterns depending on the conditions of the planet. In the case of the earth, its own strong magnetic field plays a critical role in determining the position of the bow shock. However, in the case of Mars of which has very a small intrinsic magnetic field, the bow shock is formed by the direct interaction between the solar wind and the Martian ionosphere. It is known that the position of the Martian bow shock is affected by the mass loading-effect by which the supersonic solar wind velocity becomes subsonic as the heavy ions originating from the planet are loaded on the solar wind. We simulated the Martian magnetosphere depending on the changes of the density and velocity of the solar wind by using the three-dimensional magnetohydrodynamic model built by modifying the comet code that includes the mass loading effect. The Martian exosphere model of was employed as the Martian atmosphere model, and only the photoionization by the solar radiation was considered in the ionization process of the neutral atmosphere. In the simulation result under the normal solar wind conditions, the Martian bow shock position in the subsolar point direction was consistent with the result of the previous studies. The three-dimensional simulation results produced by varying the solar wind density and velocity were all included in the range of the Martian bow shock position observed by Mariner 4, Mars 2, 3, 5, and Phobos 2. Additionally, the simulation result also showed that the change of the solar wind density had a greater effect on the Martian bow shock position than the change of the solar wind velocity. Our result may be useful in analyzing the future observation data by Martian probes.

  16. Petrogenesis of the NWA 7320 enriched martian gabbroic shergottite: Insight into the martian crust

    Science.gov (United States)

    Udry, Arya; Howarth, Geoffrey H.; Lapen, Thomas J.; Righter, Minako

    2017-05-01

    Northwest Africa (NWA) 7320 is classified as a gabbroic shergottite, the second to be recognized in the martian meteorite record. This interpretation is based on: (1) the calculated bulk-rock rare earth element (REE) concentrations, which show the highest Eu positive anomaly (Eu/Eu∗ = 2.2) of all the shergottites, reflecting accumulation of plagioclase; and (2) the highest modal abundance of maskelynitized plagioclase (50 mod.%) compared to the other shergottites. The three-phase symplectite (fayalite + hedenbergite + silica) is present in NWA 7320 and formed as a result of the breakdown of metastable pyroxene/pyroxenoid margins on coarse-grained pyroxenes. The latter is indicative of metastable overgrowths on pyroxene cores during the final stages of crystallization, followed by relatively slow cooling at subsolidus conditions. The NWA 7320 parental melt originated from an incompatible trace element enriched and oxidized (∼FMQ) source as indicated by Sm-Nd, Lu-Hf isotope systematics, ilmenite-titanomagnetite pairs, the partition coefficient of Cr in pyroxene, and merrillite REE compositions. The Ti/Al ratio of pyroxene in NWA 7320 indicates an initial crystallization depth of 30-70 km (P = 4-9 kbar). However, the largest impact craters on Mars are <8 km in depth, indicating that NWA 7320 could not have been ejected from this depth and must have had a polybaric formation history. We suggest that the pyroxene phenocrysts began to crystallize at depth, but were entrained as antecrysts in a basaltic magma ascending to shallower levels in the martian crust. In addition, plagioclase likely crystallized during magma ascent, followed by subsequent accumulation in a shallow magma intrusion or sill, resulting in the gabbroic texture. Furthermore, the similarity in the radiogenic isotope composition of NWA 7320 to that of Los Angeles and NWA 856 suggest that these meteorites were linked to common volcanic system on Mars.

  17. Survival of Salmonella on a polypropylene surface under dry conditions in relation to biofilm-formation capability.

    Science.gov (United States)

    Iibuchi, Ruriko; Hara-Kudo, Yukiko; Hasegawa, Akio; Kumagai, Susumu

    2010-08-01

    This study was conducted to gain insights into the survival of Salmonella on a polypropylene surface in relation to the ability of these bacteria to form a biofilm. We selected Salmonella strains known for the relative ease or difficulty with which they formed biofilms based on microtiter plate assays and studied the survival of these strains on polypropylene discs in a desiccation chamber by sequentially counting CFUs. The biofilm-forming strains survived longer on the plastic disc surface than did biofilm-deficient strains. The biofilm-forming strains remained at over 10(4) CFU per plate until day 175, whereas the biofilm-deficient strains decreased to below 10(2) CFU per plate on day 20 or below 10(4) CFU per plate on day 108. Extracellular materials on the polypropylene surface were observed by scanning electron microscopy and crystal violet staining for the biofilm-forming strains but not for the biofilm-deficient strains. The extracellular polymeric materials on the polypropylene surface may have protected the bacterial cells from dryness, although the possibility of some inherent resistance to environmental stresses linked to biofilm formation could not be excluded. These results indicate that Salmonella strains with high biofilm productivity may be a greater risk to human health via food contamination by surviving for longer periods compared with strains with low biofilm productivity.

  18. Soil moisture and temperature conditions affect survival and sporulation capacity of Rhododendron leaf disks infested with Phytophthora ramorum

    Science.gov (United States)

    Ebba K. Peterson; Niklaus J. Grünwald; Jennifer L. ParkeSoil

    2017-01-01

    Soilborne inoculum (infested leaf debris which has become incorporated into the soil) may be an important contributor to the persistence of the sudden oak death pathogen Phytophthora ramorum in recurrently positive nurseries. To initiate new epidemics, soilborne inoculum must not only be able to survive over time, but also be capable of...

  19. Effect of Low Temperature and Wheat Winter-Hardiness on Survival of Puccinia striiformis f. sp. tritici under Controlled Conditions.

    Directory of Open Access Journals (Sweden)

    Lijie Ma

    Full Text Available Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst, is one of the most important diseases of wheat worldwide. Understanding the survival of Pst during the overwintering period is critical for predicting Pst epidemics in the spring. Real-time quantitative PCR (qPCR methods quantifying Pst DNA and RNA (cDNA were developed and compared for the ability to quantify viable Pst in leaf tissues. Both qPCR of DNA and RNA can provide reliable measurement of viable Pst in plant tissues prior to the late sporulation stage for which qPCR of DNA gave a much higher estimate of fungal biomass than qPCR of RNA. The percentage of Pst biomass that was viable in detached and attached leaves under low temperatures decreased over time. Pst survived longer on attached leaves than on detached leaves. The survival of Pst in cultivars with strong winter-hardiness at 0°C and -5°C was greater than those with weak winter-hardiness. However, such differences in Pst survival among cultivars were negligible at -10, -15 and -20°C. Results indicated that Pst mycelia inside green leaves can also be killed by low temperatures rather than through death of green leaves under low temperatures. The relationship of Pst survival in attached leaves with temperature and winter-hardiness was well described by logistic models. Further field evaluation is necessary to assess whether inclusion of other factors such as moisture and snow cover could improve the model performance in predicting Pst overwintering potential, and hence the epidemic in spring.

  20. Conditional survival in pediatric malignancies: analysis of data from the Childhood Cancer Survivor Study and the Surveillance, Epidemiology, and End Results Program.

    Science.gov (United States)

    Mertens, Ann C; Yong, Jian; Dietz, Andrew C; Kreiter, Erin; Yasui, Yutaka; Bleyer, Archie; Armstrong, Gregory T; Robison, Leslie L; Wasilewski-Masker, Karen

    2015-04-01

    Long-term survivors of pediatric cancer are at risk of life-threatening late effects of their cancer. Previous studies have shown excesses in long-term mortality within high-risk groups defined by demographic and treatment characteristics. To investigate conditional survival in a pediatric cancer population, the authors performed an analysis of conditional survival in the original Childhood Cancer Survivor Study (CCSS) cohort and the Surveillance, Epidemiology, and End Results (SEER) database registry. The overall probability of death for patients at 5 years and 10 years after they survived 5, 10, 15, and 20 years since cancer diagnosis and cause-specific death in 10 years for 5-year survivors were estimated using the cumulative incidence method. Among patients in the CCSS and SEER cohorts who were alive 5 years after their cancer diagnosis, within each diagnosis group at least 92% were alive in the subsequent 5 years, except for patients with leukemia, of whom only 88% of 5-year survivors remained alive in the subsequent 5 years. The probability of all-cause mortality in the next 10 years among patients who survived at least 5 years after diagnosis was 8.8% in CCSS and 10.6% in SEER, approximately 75% of which was due to neoplasms as the cause of death. The risk of death among survivors of pediatric cancer in 10 years can vary between diagnosis groups by at most 12%, even up to 20 years after diagnosis. This information is clinically significant when counseling patients regarding their conditional survival, particularly when survivors are seen in long-term follow-up. © 2014 American Cancer Society.

  1. Microencapsulation of Lactobacillus rhamnosus GG by Transglutaminase Cross-Linked Soy Protein Isolate to Improve Survival in Simulated Gastrointestinal Conditions and Yoghurt.

    Science.gov (United States)

    Li, Chun; Wang, Chun-Ling; Sun, Yu; Li, Ai-Li; Liu, Fei; Meng, Xiang-Chen

    2016-07-01

    Microencapsulation is an effective way to improve the survival of probiotics in simulated gastrointestinal (GI) conditions and yoghurt. In this study, microencapsulation of Lactobacillus rhamnosus GG (LGG) was prepared by first cross-linking of soy protein isolate (SPI) using transglutaminase (TGase), followed by embedding the bacteria in cross-linked SPI, and then freeze-drying. The survival of microencapsulated LGG was evaluated in simulated GI conditions and yoghurt. The results showed that a high microencapsulation yield of 67.4% was obtained. The diameter of the microencapsulated LGG was in the range of 52.83 to 275.16 μm. Water activity did not differ between free and microencapsulated LGG after freeze-drying. The survival of microencapsulated LGG under simulated gastric juice (pH 2.5 and 3.6), intestinal juice (0.3% and 2% bile salt) and storage at 4 °C were significantly higher than that of free cells. The survival of LGG in TGase cross-linked SPI microcapsules was also improved to 14.5 ± 0.5% during storage in yoghurt. The microencapsulation of probiotics by TGase-treated SPI can be a suitable alternative to polysaccharide gelation technologies. © 2016 Institute of Food Technologists®

  2. Noachian Martian Volcanics a Water Source

    Science.gov (United States)

    Zent, A. P.; Glaze, L. S.; Baloga, S. M.; Fonda, Mark (Technical Monitor)

    2002-01-01

    H2O was supplied to the Noachian atmosphere by eruptions, or in association with large impacts. Most water outgassed into an extremely cold atmosphere, and condensate deposits were inevitable. High heat flow could lead to subglacial melting only if ice thicknesses were greater than 500-1000m, which is extremely unlikely. Subareal melting and flow is contingent upon temperatures periodically exceeding 273 K, and retarding evaporative loss of the flow. In still air, evaporation into a dry atmosphere is in the free convection regime, and a stream with 2 cu m/s discharge, flowing 1 m/s could persist for hundreds of days and cover distances greater than any valley reach. The zero-wind-shear condition is considered implausible however. We investigate the possibility that evaporation rates were suppressed because the atmosphere was regionally charged with H2O as it moved over snow/ice fields. Our initial concern is precipitation from volcanic plumes. A Kilauea-style eruption on the martian surface would cover a 10km circular deposit with 10cm of H2O, if all H2O could be precipitated near the vent. The characteristics of the eruption at the vent, (vent size, temperature, H2O content, etc.) are independent of the environmental conditions. The subsequent behavior of the plume, including precipitation of ash and H2O condensate depends strongly on the environment. Hence, the proximal fate of volcanic H2O is amenable to treatment in a model. A simple bulk thermodynamic model of the rise of an H2O plume through a stably stratified CO2 atmosphere, with only adiabatic cooling, produces runaway plume rise. A more complex treatment includes the effects of latent heat release, wind shear along the plume, divergence of ash and H2O, and will yield more realistic estimates of H2O transport in eruptive plumes. Results of these simulations will be presented.

  3. Short communication: Latin-style fresh cheese enhances lactic acid bacteria survival but not Listeria monocytogenes resistance under in vitro simulated gastrointestinal conditions.

    Science.gov (United States)

    Silva, C C G; Domingos-Lopes, M F P; Magalhães, V A F; Freitas, D A S R; Coelho, M C; Rosa, H J D; Dapkevicius, M L N E

    2015-07-01

    Different studies in humans have provided evidence about the health benefits of probiotics. However, most probiotic strains do not maintain good viability in the harsh conditions of the gastrointestinal tract (GIT). In the present study, Latin-style fresh cheese produced with potential probiotic bacteria was tested to evaluate this cheese type as a food carrier for the delivery of viable microorganisms after exposure to simulated GIT conditions. The resistance of 28 lactic acid bacteria (LAB) strains and Listeria monocytogenes upon exposure to acidic conditions (pH 2.5) and bile and pancreatic enzymes (0.3% of bile salts and 0.1% of pancreatin) was evaluated in vitro. When compared with fresh cultures, fresh cheese greatly improved LAB survival to simulated GIT conditions, as no loss of viability was observed in either acidic conditions (pH 2.5) or bile salts and pancreatin environment over a 3-h period. In opposition, L. monocytogenes did not survive after 1h under acidic conditions. These data demonstrated that Latin-style fresh cheese could play an important role in probiotic protection against gastrointestinal juices, enhancing delivery within the gut and thereby maximizing potential health benefits of LAB. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  4. Influence of age and rearing conditions of a fish on the chance to survive in the wild

    OpenAIRE

    Lyach, Roman

    2011-01-01

    The task of this thesis is to summarize all the most important biotic and abiotic factors that can influence chances of reared fish to survive in the wild. It contains some of the most frequently reared and popular fishes, such as Sander lucioperca (pike perch), Samo trutta (trout), Micropterus salmoides (largemouth bass), Esox lucius (northern pike), Esox masquinongy (muskellunge) and the hybrid of northern pike and muskellunge, the tiger muskellunge. Mainly the factors such as success, surv...

  5. Valence State Partitioning of Vanadium Between Olivine-Melt in Olivine-Phyric Martian Basalts. Defining the fO2 of the Martian Mantle.

    Science.gov (United States)

    Shearer, C.; McKay, G.; Papike, J.; Karner, J.; Sutton, S.

    2005-12-01

    Several recent studies have demonstrated that the fO2 in martian basalts varies by 2 to 3 log units and is correlated with geochemical parameters such as LREE/HREE, initial 87Sr/86Sr, and initial d. These correlations have been interpreted to indicate the presence of reduced, incompatible element-depleted and oxidized, incompatible element-enriched reservoirs that were produced during early stages of martian differentiation. Olivine-phyric basalts represent the closest approximation of primary martian basalts in the meteorite collection. Therefore, gaining a better understanding of the fO2 and incompatible element characteristics of the earliest phase (olivine) in these basalts may provide a clearer view into the martian mantle. Using the bulk composition of Yamato 980459 (an olivine-phyric basaltic melt composition), we conducted a series of near-liquidus experiments to determine the partitioning of V between olivine-melt at fO2 conditions between QFM and IW-1. XANES analyses of the glass indicate that the V4+/V3+ varies systematically with redox conditions of the experiments. SIMS analyses of V in glass and olivine indicated a systematic increase in DVol/melt from approximately 0.055 at QFM to approximately 0.5 at IW-1. This is consistent with the observed variation in V4+/V3+ measured in the glass by XANES and the crystal chemical preference of the olivine octahedral site for V3+ rather than V4+. Applying this oxybarometer calibration to well-defined lunar (IW-1) and terrestrial basaltic systems (QFM+0.2, Makaopuhi lava lake, Hawaii) indicate that it is vary robust over a wide range of planetary fO2 conditions. The determination of DVol/melt and incompatible element abundance using SIMS from martian olivine-phyric basalts indicate that they crystallized over a rather broad range in fO2 (IW+0.2 to IW+2) and from basaltic magmas with a range of incompatible element enrichments. These data indicate that correlations among these geochemical parameters are

  6. Paternal care decreases foraging activity and body condition, but does not impose survival costs to caring males in a Neotropical arachnid.

    Directory of Open Access Journals (Sweden)

    Gustavo S Requena

    Full Text Available Exclusive paternal care is the rarest form of parental investment in nature and theory predicts that the maintenance of this behavior depends on the balance between costs and benefits to males. Our goal was to assess costs of paternal care in the harvestman Iporangaia pustulosa, for which the benefits of this behavior in terms of egg survival have already been demonstrated. We evaluated energetic costs and mortality risks associated to paternal egg-guarding in the field. We quantified foraging activity of males and estimated how their body condition is influenced by the duration of the caring period. Additionally, we conducted a one-year capture-mark-recapture study and estimated apparent survival probabilities of caring and non-caring males to assess potential survival costs of paternal care. Our results indicate that caring males forage less frequently than non-caring individuals (males and females and that their body condition deteriorates over the course of the caring period. Thus, males willing to guard eggs may provide to females a fitness-enhancing gift of cost-free care of their offspring. Caring males, however, did not show lower survival probabilities when compared to both non-caring males and females. Reduction in mortality risks as a result of remaining stationary, combined with the benefits of improving egg survival, may have played an important and previously unsuspected role favoring the evolution of paternal care. Moreover, males exhibiting paternal care could also provide an honest signal of their quality as offspring defenders, and thus female preference for caring males could be responsible for maintaining the trait.

  7. Life on Mars: Evidence from Martian Meteorites

    Science.gov (United States)

    McKay, David S.; Thomas-Keptra, Katie L.; Clemett, Simon J.; Gibson, Everett K., Jr.; Spencer, Lauren; Wentworth, Susan J.

    2009-01-01

    New data on martian meteorite 84001 as well as new experimental studies show that thermal or shock decomposition of carbonate, the leading alternative non-biologic explanation for the unusual nanophase magnetite found in this meteorite, cannot explain the chemistry of the actual martian magnetites. This leaves the biogenic explanation as the only remaining viable hypothesis for the origin of these unique magnetites. Additional data from two other martian meteorites show a suite of biomorphs which are nearly identical between meteorites recovered from two widely different terrestrial environments (Egyptian Nile bottomlands and Antarctic ice sheets). This similarity argues against terrestrial processes as the cause of these biomorphs and supports an origin on Mars for these features.

  8. Could Giant Basin-Forming Impacts Have Killed Martian Dynamo?

    Science.gov (United States)

    Kuang, W.; Jiang, W.; Roberts, J.; Frey, H. V.

    2014-01-01

    The observed strong remanent crustal magnetization at the surface of Mars suggests an active dynamo in the past and ceased to exist around early to middle Noachian era, estimated by examining remagnetization strengths in extant and buried impact basins. We investigate whether the Martian dynamo could have been killed by these large basin-forming impacts, via numerical simulation of subcritical dynamos with impact-induced thermal heterogeneity across the core-mantle boundary. We find that subcritical dynamos are prone to the impacts centered on locations within 30 deg of the equator but can easily survive those at higher latitudes. Our results further suggest that magnetic timing places a strong constraint on postimpact polar reorientation, e.g., a minimum 16 deg polar reorientation is needed if Utopia is the dynamo killer.

  9. A search for nitrates in Martian meteorites

    Science.gov (United States)

    Grady, Monica M.; Wright, I. P.; Pillinger, C. T.

    1995-03-01

    Martian atmospheric nitrogen is highly enriched in N-15; nitrates formed by interaction of the atmosphere with the Martian regolith should therefore also be characterized by an elevated delta N-15 value. A search has been made for nitrates in two Martian meteorites, in order to determine the extent of possible regolith-atmosphere interaction. Shock-produced glass from the Elephant Moraine (EET) A79001 shergottite (E1,149) and a water-soluble extract from Nakhla were analyzed by Fourier transform infrared (FTIR) spectroscopy and stepped combustion-stable isotope mass spectrometry. FTIR of both meteorites had features at 1375/cm and 1630/cm, consistent with nitrates. On account of their low thermal stability, nitrates break down at temperatures below 600 C; in this temperature range, E1,149 yeilded approximately 1250 ppb nitrogen with delta N-15 -8 +/- 5%. If this nitrogen is from a nitrate, then it cannot be distinquished from terrestial salts by its isotopic composition. The water-soluble extract from Nakhla also released nitrogen at low temperatures, approximately 17 ppb with delta N-15 approximately -11 +/- 4%. Since Nakhla is an observed 'fall', this is unlikely to be a terrestial weathering product. Nitrates apparently occur in E1,149 and Nakhla, but in very low abundance, and their origin is unclear. The isotopic composition of the salts, which is within the range of that proposed for Martian magmatic volatiles, is far removed from that of nitrogen in the present-day Martian atmosphere. If the nitrates are Martian in origin, they did not form in recent times from reactions involving atmospheric gases. Rather, the nitrates could be the result of an earlier episode of atmospheric interaction with the regolith, or with implantation of magmatic volatiles introduced during degassing.

  10. Influence of initial seed moisture and temperature conditions during germination and emergence on seedling survival and yields of soybean (Glycine max L. Merrill

    Directory of Open Access Journals (Sweden)

    Adam Markowski

    2013-12-01

    Full Text Available Injury to soybean seedlings caused by low temperature (5°C at the beginning of germination was greatly reduced when instead of chilling (10°C a higher temperature (20°C was applied at the end of germination and during emergence. A new interpretation of the physiological mechanism involved in this reversibility of chilling injury was proposed. Hydration in water vapour of soybean seeds with initial moisture content of from 5 to 10% to a level of 30%, dry weight basis, increased seedling survival under controlled conditions of germination and emergence at respectively 5°C and l0°C as well as under natural soil conditions in field experiments both after early and late planting dates. A modified method of seed hydration in water vapour (i.e. conditioning or hardening of seeds against cold was developed for practical application. In field experiments conditioning of seeds increased seedling survival and thus also yields per unit area of plot but had no significant effect on yield per plant. Seed conditioning may have practical significance in soybean growing and for breeding purposes when equalizing the number of plants per plot is important for comparing new varieties and breeding forms.

  11. Martian Soil Inside Phoenix's Robotic Arm Scoop

    Science.gov (United States)

    2008-01-01

    This image from NASA's Phoenix Mars Lander's Robotic Arm Camera (RAC) shows material from the Martian surface captured by the Robotic Arm (RA) scoop during its first test dig and dump on the seventh Martian day of the mission, or Sol 7 (June 1, 2008). The test sample shown was taken from the digging area informally known as 'Knave of Hearts.' The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  12. Geopolymers from lunar and Martian soil simulants

    Science.gov (United States)

    Alexiadis, Alessio; Alberini, Federico; Meyer, Marit E.

    2017-01-01

    This work discusses the geopolymerization of lunar dust simulant JSC LUNAR-1A and Martian dust simulant JSC MARS-1A. The geopolymerization of JSC LUNAR-1A occurs easily and produces a hard, rock-like, material. The geopolymerization of JSC MARS-1A requires milling to reduce the particle size. Tests were carried out to measure, for both JSC LUNAR-1A and JSC MARS-1A geopolymers, the maximum compressive and flexural strengths. In the case of the lunar simulant, these are higher than those of conventional cements. In the case of the Martian simulant, they are close to those of common building bricks.

  13. A Hypothesis for the Abiotic and Non-Martian Origins of Putative Signs of Ancient Martian Life in ALH84001

    Science.gov (United States)

    Treiman, Allan H.

    2001-01-01

    Putative evidence of martian life in ALH84001 can be explained by abiotic and non-martian processes consistent with the meteorite's geological history. Additional information is contained in the original extended abstract.

  14. Experimental Investigation of CO_2 Solubility in Primitive Martian Basalts Similar to Yamato 980459 and Implications for Martian Atmospheric Evolution

    Science.gov (United States)

    Schaub, D. R.; Stanley, B. D.; Hirschmann, M. M.

    2012-03-01

    Experimental studies on a synthetic material similar to martian meteorite Yamato 980459 showed lower than expected CO_2 solubility, implying that models of an early martian greenhouse that are dependent on CO_2 may need reexamination.

  15. Perchlorate radiolysis on Mars and the origin of martian soil reactivity.

    Science.gov (United States)

    Quinn, Richard C; Martucci, Hana F H; Miller, Stephanie R; Bryson, Charles E; Grunthaner, Frank J; Grunthaner, Paula J

    2013-06-01

    Results from the Viking biology experiments indicate the presence of reactive oxidants in martian soils that have previously been attributed to peroxide and superoxide. Instruments on the Mars Phoenix Lander and the Mars Science Laboratory detected perchlorate in martian soil, which is nonreactive under the conditions of the Viking biology experiments. We show that calcium perchlorate exposed to gamma rays decomposes in a CO2 atmosphere to form hypochlorite (ClO(-)), trapped oxygen (O2), and chlorine dioxide (ClO2). Our results show that the release of trapped O2 (g) from radiation-damaged perchlorate salts and the reaction of ClO(-) with amino acids that were added to the martian soils can explain the results of the Viking biology experiments. We conclude that neither hydrogen peroxide nor superoxide is required to explain the results of the Viking biology experiments.

  16. Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

    DEFF Research Database (Denmark)

    Bak, Ebbe N.; Zafirov, Kaloyan; Merrison, Jonathan P.

    2017-01-01

    , but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise...... lead to a production of H(2)O(2)facilitated by atmospheric O-2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can...... high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O-2 release observed in the Labeled Release and the Gas Exchange experiments...

  17. Formation of Martian Gullies by the Flow of Simultaneously Freezing and Boiling Liquid Water

    Science.gov (United States)

    Heldmann, Jennifer L.; Mellon, Michael T.; Toon, Owen B.; Pollard, Wayne H.; Mellon, Michael T.; Pitlick, John; McKay, Christopher P.; Andersen, Dale T.

    2004-01-01

    Geomorphic evidence suggests that recent gullies on Mars were formed by fluvial activity. The Martian gully features are significant because their existence implies the presence of liquid water near the surface on Mars in geologically recent times. Irrespective of the ultimate source of the fluid carving the gullies, we seek to understand the behavior of this fluid after it reaches the Martian surface. We find that, contrary to popular belief, the fluvially-carved Martian gullies require formation conditions such as now occur on Mars, outside of the temperature-pressure stability regime of liquid water. Mars Global Surveyor observations of gully length and our modeling of water stability are consistent with gully formation from the action of pure liquid water that is simultaneously boiling and freezing.

  18. Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium

    Science.gov (United States)

    Musselwhite, S.; Jones, J. H.; Shearer, C.

    2004-01-01

    This study is part of an ongoing effort to calibrate the pyroxene/melt Eu oxybarometer for conditions relevant to the martian meteorites. There is fairly good agreement between a determinations using equilibria between Fe-Ti oxides and the estimates from Eu anomalies in shergottite augites in tenns of which meteorites are more or less oxidized. The Eu calibration was for angrite composition pyroxenes which are rather extreme. However, application of a calibration for martian composition augites 113 does not significantly reduce the discrepancy between the two methods. One possible reason for this discrepancy is that augites are non-liquidus. The use of pigeonite rather than augite as the oxy-barometer phase is considered. We have conducted experiments on martian composition pigeonite/melt REE partitioning as a function of fO2.

  19. Roles for RpoS in survival of Escherichia coli during protozoan predation and in reduced moisture conditions highlight its importance in soil environments.

    Science.gov (United States)

    Somorin, Yinka; Bouchard, Guillaume; Gallagher, Joseph; Abram, Florence; Brennan, Fiona; O'Byrne, Conor

    2017-10-16

    The soil is a complex ecosystem where interactions between biotic and abiotic factors determine the survival and fate of microbial inhabitants of the system. Having previously shown that Escherichia coli requires the general stress response regulator, RpoS, to survive long term in soil, it was important to determine what specific conditions in this environment necessitate a functional RpoS. This study investigated the susceptibility of soil-persistent E. coli to predation by the single-celled eukaryotes Acanthamoeba polyphaga and Tetrahymena pyriformis, and the role RpoS plays in resisting this predation. Strain-specific differences were observed in the predation of E. coli strains, with soil-persistent strain COB583 being the most resistant to predation by both protozoans. RpoS and curli, proteinaceous fibres used for attachment to biotic and abiotic surfaces, increased the ability of E. coli to resist predation by A. polyphaga and T. pyriformis. Furthermore, soil moisture content impacted the survival of E. coli BW25113 but wild-type COB583 had similar survival irrespective of soil moisture content. Overall, this study confirmed that RpoS contributes to the resistance of E. coli to protozoan predation and that RpoS is crucial for the increased fitness of soil-persistent E. coli against predation and reduced moisture in soil. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Risk of recurrence and conditional survival in complete responders treated with TKIs plus or less locoregional therapies for metastatic renal cell carcinoma

    Science.gov (United States)

    Santini, Daniele; Santoni, Matteo; Conti, Alessandro; Procopio, Giuseppe; Verzoni, Elena; Galli, Luca; di Lorenzo, Giuseppe; De Giorgi, Ugo; De Lisi, Delia; Nicodemo, Maurizio; Maruzzo, Marco; Massari, Francesco; Buti, Sebastiano; Altobelli, Emanuela; Biasco, Elisa; Ricotta, Riccardo; Porta, Camillo; Vincenzi, Bruno; Papalia, Rocco; Marchetti, Paolo; Burattini, Luciano; Berardi, Rossana; Muto, Giovanni; Montironi, Rodolfo; Cascinu, Stefano; Tonini, Giuseppe

    2016-01-01

    PURPOSE We retrospectively analyzed the risk of recurrence and conditional Disease-Free Survival (cDFS) in 63 patients with complete remission during treatment with tirosin kinase inhibitor (TKI), alone or with local treatment in metastatic renal cell carcinoma. RESULTS 37% patients achieve CR with TKI alone, while 63% with additional loco-regional treatments. 49% patients recurred after CR, with a median Disease free survival of 28.2 months. Patients treated with multimodal approaches present lower rate of recurrence (40% vs 61%) and longer Disease free survival compared to patient treated with TKI alone (16.5 vs 41.9 months, p=0.039).Furthermore the rate of recurrence was higher in patients with brain (88%), pancreatic (71%) and bone metastasis (50%). Patients who continued TKI therapy after complete response had a longer disease free survival than patients who stopped therapy, although the difference was not significant (42.1 vs 25.1 months, p=0.254). 2y-cDFS was better in patients treated with multimodal treatment and who continued TKIs than the other patient arms. CONCLUSIONS The prognostic value of CR depends on the site where was obtained and how was obtained (with or without locoregional treatment). Cessation of TKI should be carefully considered in complete responder patients. PMID:27027342

  1. Risk of recurrence and conditional survival in complete responders treated with TKIs plus or less locoregional therapies for metastatic renal cell carcinoma.

    Science.gov (United States)

    Santini, Daniele; Santoni, Matteo; Conti, Alessandro; Procopio, Giuseppe; Verzoni, Elena; Galli, Luca; di Lorenzo, Giuseppe; De Giorgi, Ugo; De Lisi, Delia; Nicodemo, Maurizio; Maruzzo, Marco; Massari, Francesco; Buti, Sebastiano; Altobelli, Emanuela; Biasco, Elisa; Ricotta, Riccardo; Porta, Camillo; Vincenzi, Bruno; Papalia, Rocco; Marchetti, Paolo; Burattini, Luciano; Berardi, Rossana; Muto, Giovanni; Montironi, Rodolfo; Cascinu, Stefano; Tonini, Giuseppe

    2016-05-31

    We retrospectively analyzed the risk of recurrence and conditional Disease-Free Survival (cDFS) in 63 patients with complete remission during treatment with tirosin kinase inhibitor (TKI), alone or with local treatment in metastatic renal cell carcinoma. 37% patients achieve CR with TKI alone, while 63% with additional loco-regional treatments. 49% patients recurred after CR, with a median Disease free survival of 28.2 months. Patients treated with multimodal approaches present lower rate of recurrence (40% vs 61%) and longer Disease free survival compared to patient treated with TKI alone (16.5 vs 41.9 months, p=0.039).Furthermore the rate of recurrence was higher in patients with brain (88%), pancreatic (71%) and bone metastasis (50%). Patients who continued TKI therapy after complete response had a longer disease free survival than patients who stopped therapy, although the difference was not significant (42.1 vs 25.1 months, p=0.254). 2y-cDFS was better in patients treated with multimodal treatment and who continued TKIs than the other patient arms. The prognostic value of CR depends on the site where was obtained and how was obtained (with or without locoregional treatment). Cessation of TKI should be carefully considered in complete responder patients.

  2. Survival of Clostridium perfringens During Simulated Transport and Stability of Some Plasmid-borne Toxin Genes under Aerobic Conditions

    Directory of Open Access Journals (Sweden)

    Johansson A

    2006-12-01

    Full Text Available Clostridium perfringens is a pathogen of great concern in veterinary medicine, because it causes enteric diseases and different types of toxaemias in domesticated animals. It is important that bacteria in tissue samples, which have been collected in the field, survive and for the classification of C. perfringens into the correct toxin group, it is crucial that plasmid-borne genes are not lost during transportation or in the diagnostic laboratory. The objectives of this study were to investigate the survival of C. perfringens in a simulated transport of field samples and to determine the stability of the plasmid-borne toxin genes cpb1 and etx after storage at room temperature and at 4°C. Stability of the plasmid-borne genes cpb1 and etx of C. perfringens CCUG 2035, and cpb2 from C. perfringens CIP 106526, JF 2255 and 6 field isolates in aerobic atmosphere was also studied. Survival of C. perfringens was similar in all experiments. The cpb1 and etx genes were detected in all isolates from samples stored either at room temperature or at 4°C for 24–44 h. Repeated aerobic treatment of C. perfringens CCUG 2035 and CIP 106526 did not result in the loss of the plasmid-borne genes cpb1, cpb2 or etx. Plasmid-borne genes in C. perfringens were found to be more stable than generally reported. Therefore, C. perfringens toxinotyping by PCR can be performed reliably, as the risk of plasmid loss seems to be a minor problem.

  3. Survival of Clostridium perfringens During Simulated Transport and Stability of Some Plasmid-borne Toxin Genes under Aerobic Conditions

    Directory of Open Access Journals (Sweden)

    Johansson K-E

    2005-12-01

    Full Text Available Clostridium perfringens is a pathogen of great concern in veterinary medicine, because it causes enteric diseases and different types of toxaemias in domesticated animals. It is important that bacteria in tissue samples, which have been collected in the field, survive and for the classification of C. perfringens into the correct toxin group, it is crucial that plasmid-borne genes are not lost during transportation or in the diagnostic laboratory. The objectives of this study were to investigate the survival of C. perfringens in a simulated transport of field samples and to determine the stability of the plasmid-borne toxin genes cpb1 and etx after storage at room temperature and at 4°C. Stability of the plasmid-borne genes cpb1 and etx of C. perfringens CCUG 2035, and cpb2 from C. perfringens CIP 106526, JF 2255 and 6 field isolates in aerobic atmosphere was also studied. Survival of C. perfringens was similar in all experiments. The cpb1 and etx genes were detected in all isolates from samples stored either at room temperature or at 4°C for 24–44 h. Repeated aerobic treatment of C. perfringens CCUG 2035 and CIP 106526 did not result in the loss of the plasmid-borne genes cpb1, cpb2 or etx. Plasmid-borne genes in C. perfringens were found to be more stable than generally reported. Therefore, C. perfringens toxinotyping by PCR can be performed reliably, as the risk of plasmid loss seems to be a minor problem.

  4. Impact of moisture on survival of Aedes aegypti eggs and ovicidal activity of Metarhizium anisopliae under laboratory conditions

    Directory of Open Access Journals (Sweden)

    C Luz

    2008-03-01

    Full Text Available The effect of relative humidity (43%, 75%, 86% and > 98% on Aedes aegypti eggs treated with Metarhizium anisopliae or water only was tested for up to a six months exposure at 25ºC. Survival of larvae inside eggs was clearly affected by the lowest humidity (43% tested, and eclosion diminished at all humidities after increasing periods of exposure. M. anisopliae showed to have a strong ovicidal activity only at humidity close to saturation. No difference of activity was found between conidia and hyphal bodies tested. This fungus affected larvae inside eggs and has potential as a control agent of this important vector in breeding sites with high moisture.

  5. Fluidised-bed spray-drying formulations of Candida sake CPA-1 by adding biodegradable coatings to enhance their survival under stress conditions.

    Science.gov (United States)

    Carbó, Anna; Torres, Rosario; Usall, Josep; Solsona, Cristina; Teixidó, Neus

    2017-11-01

    The biocontrol agent Candida sake CPA-1 has demonstrated to be effective against several diseases on fruit. However, for application of CPA-1 under field conditions, it was necessary to mix it with a food coating to improve survival under stress conditions, as well as adherence and distribution on fruit surfaces. The objective of this study was to obtain a more competitive formulation under field conditions to be applied independently of any product. To achieve this purpose, the drying process of CPA-1 by a fluidised-bed spray-drying system together with biodegradable coatings was optimised. This approach is novel for the drying system used and the formulation obtained which was able to form a film or coating on fruit surfaces. Several substances were tested as carriers and binders, and drying temperature was optimised. The addition of protective compounds was also tested to improve survival of CPA-1 during the dehydration process. Product shelf life, biocontrol efficacy on grapes against Botrytis cinerea, and the improvement of C. sake behaviour under stress conditions were tested. The optimal temperature of drying was 55 °C and two formulations that were able to develop a coating on fruit surfaces were obtained. One of the formulations was created by using a combination of native and pregelatinised potato starch; the other formulation was obtained using maltodextrin and by adding skimmed milk and sucrose as protectant compounds. The formulated products reduced the incidence and severity of B. cinerea, and CPA-1 survival rate was increased under stress conditions of temperature and humidity.

  6. Building a prototype of a Martian base in Poland, an architectural design overview and progress report

    Science.gov (United States)

    Kozicki, Janek

    , agricultural simulations, growing plants in Martian conditions and other kinds of tests. The presented prototype focuses on the ergonomic and psychological aspects of longer stay in a Martian environment. It provides the Martian crew with a comfortable habitable space larger than DRM modules. The practical proposal is to send this base to Mars in a DRM transpor-tation module after prototype testing is completed. The author hopes that this or other similar Martian base designs will help in establishing a permanent presence of humans on Mars.

  7. Mars Gardens in the University - Red Thumbs: Growing Vegetables in Martian regolith simulant.

    Science.gov (United States)

    Guinan, Edward Francis

    2018-01-01

    Over the next few decades NASA and private enterprise missions plan to send manned missions to Mars with the ultimate aim to establish a permanent human presence on this planet. For a self-sustaining colony on Mars it will be necessary to provide food by growing plants in sheltered greenhouses on the Martian surface. As part of an undergraduate student project in Astrobiology at Villanova University, experiments are being carried out, testing how various plants grow in Martian regolith. A wide sample of plants are being grown and tested in Mars regolith simulant commercially available from The Martian Garden (TheMartian Garden.com). This Mars regolith simulant is based on Mojave Mars Simulant (MMS) developed by NASA and JPL for the Mars Phoenix mission. The MMS is based on the Mojave Saddleback basalt similar that used by JPL/NASA. Additional reagents were added to this iron rich basalt to bring the chemical content close to actual Mars regolith. The MMS used is an approximately 90% similar to regolith found on the surface of Mars - excluding poisonous perchlorates commonly found on actual Mars surface.The students have selected various vegetables and herbs to grow and test. These include carrots, spinach, dandelions, kale, soy beans, peas, onions, garlic and of course potatoes and sweet potatoes. Plants were tested in various growing conditions, using different fertilizers, and varying light conditions and compared with identical “control plants” grown in Earth soil / humus. The results of the project will be discussed from an education view point as well as from usefulness for fundamental research.We thank The Martian Garden for providing Martian regolith simulant at education discounted prices.

  8. Microencapsulation in genipin cross-linked gelatine-maltodextrin improves survival of Bifidobacterium adolescentis during exposure to in vitro gastrointestinal conditions.

    Science.gov (United States)

    Borza, Antonela D; Annan, Nana T; Moreau, Debra L; Allan-Wojtas, Paula M; Ghanem, Amyl; Rousseau, Dérick; Paulson, Allan T; Hansen, Lisbeth Truelstrup

    2010-01-01

    To improve survival during exposure to adverse conditions, probiotic Bifidobacterium adolescentis 15703T cells were encapsulated in novel mono-core and multi-core phase-separated gelatine-maltodextrin (GMD) microspheres where the gelatine (G) phase was cross-linked with genipin (GP). Microscopy showed that encapsulated cells were exclusively associated with maltodextrin (MD) core(s). Small (average diameter 37 microm) and large (70 microm) GMD and G microspheres were produced by modulating factors (e.g. mixing speed, surfactant, GP and G concentrations) affecting the size, structural stability and phase-separation. In vitro sequential gastro-intestinal (GI) juice challenge experiments revealed increased survival of cells encapsulated in GMD ( approximately 10(6-7) cfu mL(-1)) and G (approximately 10(5) cfu mL(-1)) microspheres as compared to free cells (approximately 10(4) cfu mL(-1)). In GMD microspheres, the bacteria derive energy from MD to survive during exposure to acid and bile salts. In conclusion, the novel food grade GMD microencapsulation formulation was shown to protect probiotic bifidobacteria from adverse conditions.

  9. Degradation of Adenine on the Martian Surface in the Presence of Perchlorates and Ionizing Radiation: A Reflectron Time-of-flight Mass Spectrometric Study

    Energy Technology Data Exchange (ETDEWEB)

    Góbi, Sándor; Bergantini, Alexandre; Kaiser, Ralf I., E-mail: ralfk@hawaii.edu [Department of Chemistry, University of Hawaii at Mānoa, Honolulu, HI 96822 (United States)

    2017-04-01

    The aim of the present work is to unravel the radiolytic decomposition of adenine (C{sub 5}H{sub 5}N{sub 5}) under conditions relevant to the Martian surface. Being the fundamental building block of (deoxy)ribonucleic acids, the possibility of survival of this biomolecule on the Martian surface is of primary importance to the astrobiology community. Here, neat adenine and adenine–magnesium perchlorate mixtures were prepared and irradiated with energetic electrons that simulate the secondary electrons originating from the interaction of the galactic cosmic rays with the Martian surface. Perchlorates were added to the samples since they are abundant—and therefore relevant oxidizers on the surface of Mars—and they have been previously shown to facilitate the radiolysis of organics such as glycine. The degradation of the samples were monitored in situ via Fourier transformation infrared spectroscopy and the electron ionization quadruple mass spectrometric method; temperature-programmed desorption profiles were then collected by means of the state-of-the-art single photon photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS), allowing for the detection of the species subliming from the sample. The results showed that perchlorates do increase the destruction rate of adenine by opening alternative reaction channels, including the concurrent radiolysis/oxidation of the sample. This new pathway provides a plethora of different radiolysis products that were identified for the first time. These are carbon dioxide (CO{sub 2}), isocyanic acid (HNCO), isocyanate (OCN{sup −}), carbon monoxide (CO), and nitrogen monoxide (NO); an oxidation product containing carbonyl groups (R{sub 1}R{sub 2}–C=O) with a constrained five-membered cyclic structure could also be observed. Cyanamide (H{sub 2}N–C≡N) was detected in both irradiated samples as well.

  10. Rearing conditions determine offspring survival independent of egg quality : A cross-foster experiment with Oystercatchers Haematopus ostralegus

    NARCIS (Netherlands)

    van de Pol, Martijn; Bakker, T; Saaltink, DJ; Verhulst, S; Saaltink, Dirk-Jan

    Variation in rearing conditions, due either to parental or to environmental quality, can result in offspring of different quality (e.g. body condition, immune function). However, evidence is accumulating that egg size and composition can also affect offspring quality. In Oystercatchers Haematopus

  11. Attendance at cultural events, reading books or periodicals, and making music or singing in a choir as determinants for survival: Swedish interview survey of living conditions.

    Science.gov (United States)

    Bygren, L. O.; Konlaan, B. B.; Johansson, S. E.

    1996-01-01

    OBJECTIVES: To investigate the possible influence of attendance at cultural events, reading books or periodicals, making music or singing in a choir as determinants for survival. DESIGN: A simple random sample was drawn of 15,198 individuals aged 16-74 years. Of these, 85% (12,982) were interviewed by trained non-medical interviewers between 1982 and 1983 about cultural activities. They were followed up with respect to survival until 31 December 1991. SETTING: Swedish interview survey of living conditions comprising a random sample of the adult Swedish population. SUBJECTS: 12,675 people interviewed between 1982 and 1983. MAIN OUTCOME MEASURES: Survival of subjects after controlling for eight confounding variables: age, sex, education level, income, long term disease, social network, smoking, and physical exercise. RESULTS: 6,301 men and 6,374 women were followed up; 533 men and 314 women died during this period. The control variables influenced survival in the expected directions except for social network for men; a significant negative effective was found when the analysis was made separately for men and women. We found an influence on mortality when the eight control variables were controlled for in people who rarely attended events compared with those attending most often, the relative risk being 1.57 (95% confidence interval 1.18 to 2.09). CONCLUSION: Attendance at cultural events may have a positive influence on survival. Long term follow up of large samples with confounders that are well controlled for and with the cultural stimulation more highly specified should be used to try to falsify the hypothesis before experiments start. PMID:8990990

  12. Two Bioactive Molecular Weight Fractions of a Conditioned Medium Enhance RPE Cell Survival on Age-Related Macular Degeneration and Aged Bruch's Membrane

    Science.gov (United States)

    Sugino, Ilene K.; Sun, Qian; Springer, Carola; Cheewatrakoolpong, Noounanong; Liu, Tong; Li, Hong; Zarbin, Marco A.

    2016-01-01

    Purpose To characterize molecular weight fractions of bovine corneal endothelial cell conditioned medium (CM) supporting retinal pigment epithelium (RPE) cell survival on aged and age-related macular degeneration (AMD) Bruch's membrane. Methods CM was subject to size separation using centrifugal filters. Retentate and filtrate fractions were tested for bioactivity by analyzing RPE survival on submacular Bruch's membrane of aged and AMD donor eyes and behavior on collagen I-coated tissue culture wells. Protein and peptide composition of active fractions was determined by mass spectrometry. Results Two bioactive fractions, 3-kDa filtrate and a 10-50–kDa fraction, were necessary for RPE survival on aged and AMD Bruch's membrane. The 3-kDa filtrate, but not the 10-50–kDa fraction, supported RPE growth on collagen 1‐coated tissue culture plates. Mass spectrometry of the 10-50–kDa fraction identified 175 extracellular proteins, including growth factors and extracellular matrix molecules. Transforming growth factor (TGF)β-2 was identified as unique to active CM. Peptides representing 29 unique proteins were identified in the 3-KDa filtrate. Conclusions These results indicate there is a minimum of two bioactive molecules in CM, one found in the 3-kDa filtrate and one in the 10-50–kDa fraction, and that bioactive molecules in both fractions must be present to ensure RPE survival on Bruch's membrane. Mass spectrometry analysis suggested proteins to test in future studies to identify proteins that may contribute to CM bioactivity. Translational Relevance Results of this study are the first steps in development of an adjunct to cell-based therapy to ensure cell transplant survival and functionality in AMD patients. PMID:26933521

  13. Martian Electron Foreshock: New Results from MAVEN

    Science.gov (United States)

    Mazelle, C. X.; Meziane, K.; Mitchell, D. L.; Romanelli, N. J.; McFadden, J. P.; Espley, J. R.; Connerney, J. E. P.; Halekas, J. S.; Jakosky, B. M.; Hamza, A. M.

    2016-12-01

    Observations upstream from the Martian bow shock obtained by the MAVEN Solar Wind Electron Analyzer (SWEA) experiment are presented. Significant flux enhancements associated with electrons in the energies 50-400 eV range are always observed when MAVEN spacecraft is magnetically connected to the shock. The electron flux reaches a maximum near the shock surface. In addition, electron spikes with energies up to 1.5 keV are also observed near the Martian foreshock boundary. A detailed examination of the pitch angle distribution shows that the enhanced fluxes correspond to electrons moving sunward away from Mars. Also, the full 3-D angular distributions show that the phase space density values are peaked at a non-zero pitch angle and that the electrons appear in a ring centered along the IMF direction. The gyrotropic feature is observed over a large range of the shock geometry from quasi-parallel to quasi-perpendicular. These signatures in the electron distribution function strongly suggest that the reflection off the shock is the main mechanism for the production of Martian foreshock electrons. Although striking differences exist between the Earth and Mars shock structures, these observations show strong similarities in both the Terrestrial and Martian electronic foreshocks.

  14. Gravitomagnetic Separation of Bipolar Charged Martian Dust

    Science.gov (United States)

    Arias, FJ

    2017-09-01

    In this work it is shown that magnetic anomalies on Mars can actually boost gravitational spatial separation of bipolar charged Martian dust. If so, these places are prone for high electrical activity and then formation of chemical process requiring electrical sparks.

  15. Effects of copper on development and survival rate of Paphia malabarica Chemnitz larvae under low saline condition

    Digital Repository Service at National Institute of Oceanography (India)

    Gireesh, R.; Gopinathan, C.P.

    populations. Fur- ther ecotoxicological studies on larvae and juve- niles under various environmental conditions are necessary to get a comprehensive picture of eco- logical requirements. This will help to improve the status and conservation of this species...

  16. Similar Survival for Patients Undergoing Reduced-Intensity Total Body Irradiation (TBI) Versus Myeloablative TBI as Conditioning for Allogeneic Transplant in Acute Leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Mikell, John L., E-mail: jmikell@emory.edu [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Waller, Edmund K. [Department of Hematology and Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Switchenko, Jeffrey M. [Department of Biostatistics and Bioinformatics, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Rangaraju, Sravanti; Ali, Zahir; Graiser, Michael [Department of Hematology and Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Hall, William A. [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Langston, Amelia A. [Department of Hematology and Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Esiashvili, Natia [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Khoury, H. Jean [Department of Hematology and Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Khan, Mohammad K. [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States)

    2014-06-01

    Purpose: Hematopoietic stem cell transplantation (HSCT) is the mainstay of treatment for adults with acute leukemia. Total body irradiation (TBI) remains an important part of the conditioning regimen for HCST. For those patients unable to tolerate myeloablative TBI (mTBI), reduced intensity TBI (riTBI) is commonly used. In this study we compared outcomes of patients undergoing mTBI with those of patients undergoing riTBI in our institution. Methods and Materials: We performed a retrospective review of all patients with acute leukemia who underwent TBI-based conditioning, using a prospectively acquired database of HSCT patients treated at our institution. Patient data including details of the transplantation procedure, disease status, Karnofsky performance status (KPS), response rates, toxicity, survival time, and time to progression were extracted. Patient outcomes for various radiation therapy regimens were examined. Descriptive statistical analysis was performed. Results: Between June 1985 and July 2012, 226 patients with acute leukemia underwent TBI as conditioning for HSCT. Of those patients, 180 had full radiation therapy data available; 83 had acute lymphoblastic leukemia and 94 had acute myelogenous leukemia; 45 patients received riTBI, and 135 received mTBI. Median overall survival (OS) was 13.7 months. Median relapse-free survival (RFS) for all patients was 10.2 months. Controlling for age, sex, KPS, disease status, and diagnosis, there were no significant differences in OS or RFS between patients who underwent riTBI and those who underwent mTBI (P=.402, P=.499, respectively). Median length of hospital stay was shorter for patients who received riTBI than for those who received mTBI (16 days vs 23 days, respectively; P<.001), and intensive care unit admissions were less frequent following riTBI than mTBI (2.22% vs 12.69%, respectively, P=.043). Nonrelapse survival rates were also similar (P=.186). Conclusions: No differences in OS or RFS were seen between

  17. Dependence of the Martian radiation environment on atmospheric depth: Modeling and measurement

    Science.gov (United States)

    Guo, Jingnan; Slaba, Tony C.; Zeitlin, Cary; Wimmer-Schweingruber, Robert F.; Badavi, Francis F.; Böhm, Eckart; Böttcher, Stephan; Brinza, David E.; Ehresmann, Bent; Hassler, Donald M.; Matthiä, Daniel; Rafkin, Scot

    2017-02-01

    The energetic particle environment on the Martian surface is influenced by solar and heliospheric modulation and changes in the local atmospheric pressure (or column depth). The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory rover Curiosity on the surface of Mars has been measuring this effect for over four Earth years (about two Martian years). The anticorrelation between the recorded surface Galactic Cosmic Ray-induced dose rates and pressure changes has been investigated by Rafkin et al. (2014) and the long-term solar modulation has also been empirically analyzed and modeled by Guo et al. (2015). This paper employs the newly updated HZETRN2015 code to model the Martian atmospheric shielding effect on the accumulated dose rates and the change of this effect under different solar modulation and atmospheric conditions. The modeled results are compared with the most up-to-date (from 14 August 2012 to 29 June 2016) observations of the RAD instrument on the surface of Mars. Both model and measurements agree reasonably well and show the atmospheric shielding effect under weak solar modulation conditions and the decline of this effect as solar modulation becomes stronger. This result is important for better risk estimations of future human explorations to Mars under different heliospheric and Martian atmospheric conditions.

  18. Dependence of Martian radiation environment on atmospheric depth: modeling and measurement

    Science.gov (United States)

    Guo, Jingnan; Slaba, Tony; Zeitlin, Cary; Wimmer-Schweingruber, Robert; Boehm, Eckart; Brinza, David; Ehresmann, Bent; Hassler, Donald; Matthiae, Daniel; Rafkin, Scot; Badavi, Francis

    2017-04-01

    The energetic particle environment on the Martian surface is influenced by solar and heliospheric modulation and changes in the local atmospheric pressure (or column depth). The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory (MSL) rover Curiosity on the surface of Mars has been measuring this effect for over four Earth years (about two Martian years). The anti-correlation between the recorded surface Galactic Cosmic Ray (GCR) induced dose rates and pressure changes has been investigated by Rafkin et al. (2014) and the long-term solar modulation have also been empirically analyzed and modeled by Guo et al. (2015). This paper employs the newly updated HZETRN2015 code to model the Martian atmospheric shielding effect on the accumulated dose rates and the change of this effect under different solar modulation and atmospheric conditions. The modeled results are compared with the most up-to-date (from 14 August 2012 until 29 June 2016) observations of the RAD instrument on the surface of Mars. Both model and measurements agree reasonably well and show the atmospheric shielding effect under weak solar modulation conditions and the decline of this effect as solar modulation becomes stronger. This result is important for better risk estimations of future human explorations to Mars under different heliospheric and Martian atmospheric conditions.

  19. Possible applications of aquatic bioregenerative life support modules for food production in a Martian base

    Science.gov (United States)

    Bluem, V.; Paris, F.

    Water is the essential precondition of life in general and also for the establishment of a martian base suitable for long duration stays of humans. It is not yet proven if there is indeed a ``frozen ocean'' under the surface of mars but if this could be verified it would open innovative aspects for the construction of bioregenerative life support systems (BLSS). In a general concept higher plants will play the predominant role in a martian BLSS. It is not clear, however, how these will grow and bring seed in reduced gravity and there may be differences in the productivity in comparison to Earth conditions. Therefore, organisms which are already adapted to low gravity conditions, namely non-gravitropic aquatic plants and also aquatic animals may be used to enhance the functionality of the martian BLSS as a whole. It has been shown already with the so-called C.E.B.A.S. MINIMODULE in the STS-89 and STS-90 spaceshuttle missions that the water plant Ceratophyllum demersum has an undisturbed and high biomass production under space conditions. Moreover, the teleost fish species Xiphophorus helleri adapted easily to the micro-g environment and maintained its normal reproductive functions. Based on this findings a possible scenario is presented in which aquatic plant production modules and combined animal-plant production systems may be used for human food production and water and air regeneration in a martian base.

  20. Nature of Reduced Carbon in Martian Meteorites

    Science.gov (United States)

    Gibson, Everett K., Jr.; McKay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; White, L. M.

    2012-01-01

    Martian meteorites provide important information on the nature of reduced carbon components present on Mars throughout its history. The first in situ analyses for carbon on the surface of Mars by the Viking landers yielded disappointing results. With the recognition of Martian meteorites on Earth, investigations have shown carbon-bearing phases exist on Mars. Studies have yielded presence of reduced carbon, carbonates and inferred graphitic carbon phases. Samples ranging in age from the first approximately 4 Ga of Mars history [e.g. ALH84001] to nakhlites with a crystallization age of 1.3 Ga [e.g. Nakhla] with aqueous alteration processes occurring 0.5-0.7 Ga after crystallizaton. Shergottites demonstrate formation ages around 165-500 Ma with younger aqueous alterations events. Only a limited number of the Martian meteorites do not show evidence of significance terrestrial alterations. Selected areas within ALH84001, Nakhla, Yamato 000593 and possibly Tissint are suitable for study of their indigenous reduced carbon bearing phases. Nakhla possesses discrete, well-defined carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of Nakhla's organic phases the presence of pre-terrestrial organics is now recognized. The reduced carbon-bearing phases appear to have been deposited during preterrestrial aqueous alteration events that produced clays. In addition, the microcrystalline layers of Nakhla's iddingsite have discrete units of salt crystals suggestive of evaporation processes. While we can only speculate on the origin of these unique carbonaceous structures, we note that the significance of such observations is that it may allow us to understand the role of Martian carbon as seen in the Martian meteorites with obvious implications for astrobiology and the pre-biotic evolution of Mars. In any case, our observations strongly suggest that reduced organic carbon exists as micrometer- size, discrete structures

  1. Initiation and growth of martian ice lenses

    Science.gov (United States)

    Sizemore, Hanna G.; Zent, Aaron P.; Rempel, Alan W.

    2015-05-01

    Water ice in the upper meters of the martian regolith is a major volatile reservoir. Although the geographic extent, burial depth, and thermal stability of this shallow ice are well understood, its origin, history, and stratigraphy are not. Over the past decade, a growing body of observational evidence has indicated that shallow ground ice exceeds the pore volume of its host soil over large regions of both martian hemispheres. This is confounding, given that (1) the physical theory that accurately predicts the location of ground ice also assumes that ice should be pore-filling in the upper meter of regolith, and (2) the Phoenix spacecraft uncovered far more pore-filling ice than excess ice at its landing site in the northern hemisphere. The development of ice lenses by low-temperature in situ segregation - analogous to the processes that generate frost heave on Earth - has been hypothesized to explain shallow excess ice on Mars. We have developed a numerical model of ice lens initiation and growth in the martian environment, and used it to test this hypothesis for the first time. We carried out a large suite of numerical simulations in order to place quantitative constraints on the timing and location of ice lens initiation, and on the magnitude of ice lens growth in a variety of host soils. We find that ice lens initiation is a ubiquitous process in the martian high latitudes, but the ultimate magnitude of lens growth, or frost heave, is sensitive to the properties of the host soil. Depending on the specific properties of martian soils, in situ segregation may be a very slow process sufficient to explain the excess ice observed in the Dodo-Goldilocks trench at the Phoenix landing site, but without regionally significant effects. Alternatively, if clay-sized particles or perchlorate salts are present, in situ segregation may be a vigorous process that has significantly affected the stratigraphy of ground ice in the upper meter of regolith throughout the high

  2. Insights into the Martian Regolith from Martian Meteorite Northwest Africa 7034

    Science.gov (United States)

    McCubbin, Francis M.; Boyce, Jeremy W.; Szabo, Timea; Santos, Alison R.; Domokos, Gabor; Vazquez, Jorge; Moser, Desmond E.; Jerolmack, Douglas J.; Keller, Lindsay P.; Tartese, Romain

    2015-01-01

    Everything we know about sedimentary processes on Mars is gleaned from remote sensing observations. Here we report insights from meteorite Northwest Africa (NWA) 7034, which is a water-rich martian regolith breccia that hosts both igneous and sedimentary clasts. The sedimentary clasts in NWA 7034 are poorly-sorted clastic siltstones that we refer to as protobreccia clasts. These protobreccia clasts record aqueous alteration process that occurred prior to breccia formation. The aqueous alteration appears to have occurred at relatively low Eh, high pH conditions based on the co-precipitation of pyrite and magnetite, and the concomitant loss of SiO2 from the system. To determine the origin of the NWA 7034 breccia, we examined the textures and grain-shape characteristics of NWA 7034 clasts. The shapes of the clasts are consistent with rock fragmentation in the absence of transport. Coupled with the clast size distribution, we interpret the protolith of NWA 7034 to have been deposited by atmospheric rainout resulting from pyroclastic eruptions and/or asteroid impacts. Cross-cutting and inclusion relationships and U-Pb data from zircon, baddelleyite, and apatite indicate NWA 7034 lithification occurred at 1.4-1.5 Ga, during a short-lived hydrothermal event at 600-700 C that was texturally imprinted upon the submicron groundmass. The hydrothermal event caused Pb-loss from apatite and U-rich metamict zircons, and it caused partial transformation of pyrite to submicron mixtures of magnetite and maghemite, indicating the fluid had higher Eh than the fluid that caused pyrite-magnetite precipitation in the protobreccia clasts. NWA 7034 also hosts ancient 4.4 Ga crustal materials in the form of baddelleyites and zircons, providing up to a 2.9 Ga record of martian geologic history. This work demonstrates the incredible value of sedimentary basins as scientific targets for Mars sample return missions, but it also highlights the importance of targeting samples that have not been

  3. Mercury critical concentrations to Enchytraeus crypticus (Annelida: Oligochaeta) under normal and extreme conditions of moisture in tropical soils - Reproduction and survival.

    Science.gov (United States)

    Buch, Andressa Cristhy; Schmelz, Rüdiger M; Niva, Cintia Carla; Correia, Maria Elizabeth Fernandes; Silva-Filho, Emmanoel Vieira

    2017-05-01

    Soil provides many ecosystem services that are essential to maintain its quality and healthy development of the flora, fauna and human well-being. Environmental mercury levels may harm the survival and diversity of the soil fauna. In this respect, efforts have been made to establish limit values of mercury (Hg) in soils to terrestrial fauna. Soil organisms such as earthworms and enchytraeids have intimate contact with trace metals in soil by their oral and dermal routes, reflecting the potentially adverse effects of this contaminant. The main goal of this study was to obtain Hg critical concentrations under normal and extreme conditions of moisture in tropical soils to Enchytraeus crypticus to order to assess if climate change may potentiate their acute and chronic toxicity effects. Tropical soils were sampled from of two Forest Conservation Units of the Rio de Janeiro State - Brazil, which has been contaminated by Hg atmospheric depositions. Worms were exposed to three moisture conditions, at 20%, 50% and 80% of water holding capacity, respectively, and in combination with different Hg (HgCl2) concentrations spiked in three types of tropical soil (two natural soils and one artificial soil). The tested concentrations ranged from 0 to 512mg Hg kg-1 dry weight. Results indicate that the Hg toxicity is higher under increased conditions of moisture, significantly affecting survival and reproduction rate. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Field Emission Gun Scanning Electron (FEGSEM) and Transmission Electron (TEM) Microscopy of Phyllosilicates in Martian Meteorites ALH84001, Nakhla, and Shergotty

    Science.gov (United States)

    Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Gibson, Everett K.

    2000-01-01

    Here we document the occurrence of phyllosilicates and alteration phases in three martian meteorites, suggest formation conditions required for phyllosilicate formation and speculate on the extent of fluid:rock interactions during the past history of Mars.

  5. Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian Shergottites

    Science.gov (United States)

    Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.

    2009-01-01

    The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.

  6. The genome of the Antarctic polyextremophile Nesterenkonia sp. AN1 reveals adaptive strategies for survival under multiple stress conditions.

    Science.gov (United States)

    Aliyu, Habibu; De Maayer, Pieter; Cowan, Don

    2016-04-01

    Nesterenkonia sp. AN1 is a polyextremophile isolated from Antarctic desert soil. Genomic analyses and genome comparisons with three mesophilic Nesterenkonia strains indicated that the unique genome fraction of Nesterenkonia sp. AN1 contains adaptive features implicated in the response to cold stress including modulation of membrane fluidity as well as response to cold-associated osmotic and oxidative stress. The core genome also encodes a number of putative cold stress response proteins. RNA-Seq-based transcriptome analyses of Nesterenkonia sp. AN1 grown at 5ºC and 21°C showed that there was significant induction of transcripts that code for antioxidants at 5ºC, demonstrated by the upregulation of sodA, bcp and bpoA2. There was also overexpression of universal stress protein genes related to uspA, along with genes encoding other characterized cold stress features. Genes encoding the two key enzymes of the glyoxylate cycle, isocitrate lyase (ICL) and malate synthase (AceB) were induced at 5ºC, suggesting possible adaptation strategies for energy metabolism in cold habitats. These genomic features may contribute to the survival of Nesterenkonia sp. AN1 in arid Antarctic soils. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. The impact of modified nano-carbon black on the earthworm Eisenia fetida under turfgrass growing conditions: Assessment of survival, biomass, and antioxidant enzymatic activities.

    Science.gov (United States)

    Zhao, Shulan; He, Lu; Lu, Yunfeng; Duo, Lian

    2017-09-15

    Modified nano-carbon adsorbents have been employed in the immobilization of heavy metals in soil due to their good adsorption capabilities regarding metal ions. However, an assessment of their risks has not been extensively performed with soil organisms. To assess the toxic effects of three types of modified nano-carbon black (CB) on soil organisms, a laboratory test was conducted to expose the earthworm Eisenia fetida to artificial soil supplemented with 5% H2SO4-, HNO3- and KMnO4-modified nano-CB (SCB, NCB and KCB, respectively) under turfgrass growing conditions. The tested earthworms were systematically investigated for survival, biomass and the activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). SCB and NCB were found to be more toxic and ecologically dangerous to E. fetida because significant decreases in biomass and survival were observed after 35- and 60-d exposures and the survival rate showed a tendency to decrease with exposure duration. The activities of SOD, CAT and POD were inhibited in all treatments with modified nano-CBs at 35- and 60-d, which indicated that oxidative stress was induced by modified nano-CBs. The results suggest that there is potential harm to earthworms in soil with 5% modified nano-CB and that it deserves special attention. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Encapsulation of the therapeutic microbe Akkermansia muciniphila in a double emulsion enhances survival in simulated gastric conditions

    NARCIS (Netherlands)

    Ark, van der Kees C.H.; Nugroho, Avis Dwi Wahyu; Berton-Carabin, Claire; Wang, Che; Belzer, Clara; Vos, de Willem M.; Schroen, Karin

    2017-01-01

    There is considerable attention for developing Akkermansia muciniphila as a new therapeutic microbe since it has shown to prevent diet-induced obesity and type 2 diabetes in mice. However, A. muciniphila is sensitive to gastric conditions such as low pH and oxygen. Therefore, we explored the

  9. Association between use of air-conditioning or fan and survival of elderly febrile patients: a prospective study.

    Science.gov (United States)

    Theocharis, G; Tansarli, G S; Mavros, M N; Spiropoulos, T; Barbas, S G; Falagas, M E

    2013-09-01

    Elderly individuals are more susceptible to excess summer heat. We sought to examine whether the use of cooling systems (air-conditioning or fan) affected the clinical outcomes of elderly febrile patients. We prospectively followed elderly (≥ 75 years old) febrile patients requesting the medical services of the SOS Doctors (a network of physicians performing house-call visits) from July 10 to August 20, 2011. Patients who used cooling systems ("users") were compared with those who did not ("non-users") regarding mortality, clinical outcome of primary illness (improvement or deterioration), and emergency hospitalization. Prospectively collected data were available for 339 individual elderly febrile patients. "Users" had lower mortality (10 % vs. 19 %, p air-conditioning and fan regarding mortality or clinical improvement, but fan use was associated with more hospitalizations (37 % vs. 19 %, p conditions), the sole variable significantly associated with mortality was the non-use of cooling systems [odds ratio (OR): 2.18, 95 % confidence interval (CI): 1.06-4.50]. The use of air-conditioning or fan during hot summer periods appeared to be beneficial for elderly febrile patients living in a large city. Large prospective studies are warranted in order to provide further insight into potential individual and public health initiatives aiming to alleviate the impact of excess summer heat on the health of elderly patients.

  10. Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions

    DEFF Research Database (Denmark)

    Johansen, Anders; Bangsø Nielsen, Henrik; Hansen, Christian M.

    2013-01-01

    ) was very clear as complete mortality, irrespective of weed species, was reached after less than 2 days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzinckia micrantha still...

  11. High Resolution Observations of Escaping Ions in the Martian Magnetotail

    Science.gov (United States)

    Halekas, J. S.; Raman, C.; Brain, D.; DiBraccio, G. A.; Harada, Y.; McFadden, J. P.; Mitchell, D. L.; Connerney, J. E. P.; Jakosky, B. M.

    2016-12-01

    Ions escape from the Martian upper atmosphere via a number of channels, including the central plasmasheet of the magnetotail. Mars Express observations show that the heavy ions O+ and O2+ escaping through the central tail often have approximately the same energy, suggesting acceleration in a quasi-static electric field, which has been interpreted as a Hall electric field. The Solar Wind Ion Analyzer (SWIA) on MAVEN was designed to measure the upstream solar wind. However, during orbit segments with appropriate spacecraft attitude, SWIA can also make high resolution measurements of escaping ions in the tail. During the prime mission, these observations were only returned sporadically, during periods of intense escaping fluxes that fortuitously triggered a mode switch. Now, in the extended mission, we return high resolution observations from SWIA routinely. Some of these high resolution measurements reveal slight differences in both the direction and energy of escaping O+ and O2+ ions, which may help determine the acceleration process(es). We investigate the location and solar wind conditions for which the escaping ions separate in energy and angle and the systematics of their energies and flow vectors, and discuss the implications for ion acceleration and the overall picture of Martian atmospheric escape.

  12. Martian Atmospheric Dust Mitigation for ISRU Intakes via Electrostatic Precipitation

    Science.gov (United States)

    Phillips, James R., III; Pollard, Jacob R. S.; Johansen, Michael R.; Mackey, Paul J.; Clements, J. Sid; Calle, Carlos I.

    2016-01-01

    The Mars 2020 and Mars Sample Return missions expected to fly to Mars within the next ten years will each include an In Situ Resource Utilization (ISRU) system. They convert carbon dioxide in the Martian atmosphere into consumable oxygen at 1% and 20% of the rate required by a full scale human exploration Mars mission, respectively. The ISRU systems will need to draw in the surrounding atmosphere at a rate of 110L/min and 550L/min, respectively, in order to meet their oxygen production goals. Over the duration of each respective mission, a total atmospheric dust mass of 4.86g and 243g will be drawn into each system, respectively. Ingestion of large quantities of dust may interfere with ISRU operations, so a dust mitigation device will be required. The atmospheric volume and dust mass flow rates above will be utilized to simulate Martian environmental conditions in a laboratory electrostatic precipitator being developed to provide active dust mitigation support for atmospheric ISRU systems such as these.

  13. Determination of the Toxicity to Aquatic Organisms of HMX and Related Wastewater Constituents. Part 1. The Effects of Food Concentration, Animal Interactions and Water Volume on Survival Growth and Reproduction of Daphnia magna under Flow-through Conditions.

    Science.gov (United States)

    1983-01-01

    Effects of polychlorinated biphenyl’s (PCB’s) on survival and reproduction of Daphnia, Gammarus , and Tanytarsus. Trans. Amer. Fish. Soc. 103(4) : 722-728...WASTEWATER CONSTITUENTS Ruff 1: * THE EFFECTS OF FOOD CONCENTRATION, ANIMAL INTERACTIONS AND WATER VOLUME ON SURVIVAL, GROWTH AND REPRODUCTION OF Daphnia...OF FOOD CONCENTRATION, ANIMAL INTERACTIONS AND WATER VOLUME ON SURVIVAL, GROWTH AND REPRODUCTION OF Daphnia magna UNDER FLOW-THROUGH CONDITIONS

  14. Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

    Science.gov (United States)

    Bak, Ebbe N.; Zafirov, Kaloyan; Merrison, Jonathan P.; Jensen, Svend J. Knak; Nørnberg, Per; Gunnlaugsson, Haraldur P.; Finster, Kai

    2017-09-01

    The results of the Labeled Release and the Gas Exchange experiments conducted on Mars by the Viking Landers show that compounds in the Martian soil can cause oxidation of organics and a release of oxygen in the presence of water. Several sources have been proposed for the oxidizing compounds, but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise to oxidants in the form of hydrogen peroxide (H2O2) and hydroxyl radicals (ṡOH). We found that silicate samples abraded in simulated Martian atmospheres gave rise to a significant production of H2O2 and ṡOH upon contact with water. Our experiments demonstrated that abraded silicates could lead to a production of H2O2 facilitated by atmospheric O2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can cause dissociation of CO2 and through subsequent reactions lead to a production of H2O2. These results indicate that the reactions linked to electrical discharges are the dominant source of H2O2 during saltation of silicates in a simulated Martian atmosphere, given the low pressure and the relatively high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O2 release observed in the Labeled Release and the Gas Exchange experiments. Furthermore, the release of H2O2 and ṡOH from abraded silicates could have a negative effect on the persistence of organic compounds in the Martian soil and the habitability of the Martian surface.

  15. Investigating the photostability of carboxylic acids exposed to Mars surface ultraviolet radiation conditions.

    Science.gov (United States)

    Stalport, F; Coll, P; Szopa, C; Cottin, H; Raulin, F

    2009-01-01

    The detection and identification of organic molecules on Mars are of primary importance to establish the existence of a possible ancient prebiotic chemistry or even biological activity. The harsh environmental conditions at the surface of Mars could explain why the Viking probes-the only efforts, to date, to search for organics on Mars-detected no organic matter. To investigate the nature, abundance, and stability of organic molecules that could survive such environmental conditions, we developed a series of experiments that simulate martian surface environmental conditions. Here, we present results with regard to the impact of solar UV radiation on various carboxylic acids, such as mellitic acid, which are of astrobiological interest to the study of Mars. Our results show that at least one carboxylic acid, mellitic acid, could produce a resistant compound-benzenehexacarboxylic acid-trianhydride (C(12)O(9))-when exposed to martian surface radiation conditions. The formation of such products could contribute to the presence of organic matter in the martian regolith, which should be considered a primary target for in situ molecular analyses during future surface missions.

  16. The influence of different salinity conditions on egg buoyancy and development and yolk sac larval survival and morphometric traits of Baltic Sea sprat (Sprattus sprattus balticus Schneider

    Directory of Open Access Journals (Sweden)

    Christoph Petereit

    2009-10-01

    Full Text Available The small pelagic sprat (Sprattus sprattus is a key ecologic player in the Baltic Sea. However, there is long-term variability in recruitment which is thought to be influenced by fluctuations in abiotic and biotic conditions experienced during the early life stages. This study concentrates on the influence of different ambient salinities on sprat egg development, egg buoyancy and survival as well as early yolk sac larval morphometric traits. Egg buoyancy significantly decreased with increasing salinity experienced during fertilization and/or incubation experiments. Field egg buoyancy measurements in 2007 and 2008 exhibited annual and seasonal differences in specific gravity, potentially associated with changes in adult sprat vertical distribution. Neither egg development time nor the duration of the yolk sac phase differed among salinity treatments. At eye pigmentation, larval standard length exhibited high variance among individuals but did not differ among treatments. The largest ecological impact of salinity experienced during spawning was the modification the buoyancy of eggs and yolk sac larvae, which determines their vertical habitat in the Baltic Sea. There are strong thermo- and oxyclines in the Baltic Sea, and thus salinity can indirectly impact the survival of these early life stages by modifying the ambient temperatures and oxygen conditions experienced.

  17. Cell culture condition-dependent impact of AGE-rich food extracts on kinase activation and cell survival on human fibroblasts.

    Science.gov (United States)

    Nass, Norbert; Weissenberg, Kristian; Somoza, Veronika; Ruhs, Stefanie; Silber, Rolf-Edgar; Simm, Andreas

    2014-03-01

    Advanced glycation end products (AGEs) are stable end products of the Maillard reaction. Effects of food extracts are often initially analysed in cellular test systems and it is not clear how different cell culture conditions might influence the results. Therefore, we compared the effects of two models for AGE-rich food, bread crust and coffee extract (CE) on WI-38 human lung fibroblasts under different cell culture conditions (sub-confluent versus confluent cells, with and without serum). WI-38 cells responded to coffee and bread crust extract (BCE) with a rapid phosphorylation of PKB (AKT), p42/44 MAPK (ERK 1/2) and p38 MAPK, strongly depending on culture conditions. BCE resulted in increased cell numbers, whereas CE appeared to be cytotoxic. When cell numbers under all culture conditions and treatments were correlated with kinase phosphorylation, the relation between phospho-p38 MAPK and phospho-AKT represented a good, cell culture condition-independent predictor of cell survival.

  18. Microencapsulation of Lactobacillus plantarum (mtcc 5422) by spray-freeze-drying method and evaluation of survival in simulated gastrointestinal conditions.

    Science.gov (United States)

    Dolly, Priyanka; Anishaparvin, A; Joseph, G S; Anandharamakrishnan, C

    2011-01-01

    Spray-drying (SD) and freeze-drying (FD) are widely used methods for microencapsulation of heat-sensitive materials like probiotics for long-term preservation and transport. Spray-freeze-drying (SFD) is relatively a new technique that involves spraying a solution into a cold medium and removal of solvent (water) by conventional vacuum FD method. In this study, the SFD microencapsulated Lactobacillus plantarum powder (1:1 and 1:1.5 core-to-wall ratios of whey protein) is compared with the microencapsulated powders produced by FD and SD methods. The SFD and FD processed microencapsulated powder show 20% higher cell viability than the SD samples. In simulated gastrointestinal conditions, the SFD and FD cells show up to 4 h better tolerance than SD samples and unencapsulated cells in acidic and pepsin condition. The morphology of SFD samples shows particles almost in spherical shape with numerous fine pores, which in turn results in good rehydration behaviour of the powdered product.

  19. On to Mars! chronicles of Martian simulations

    CERN Document Server

    PLETSER, Vladimir

    2018-01-01

    This book introduces the Martian simulations, one installed on Devon Island, an uninhabited island in the Canadian Arctic, well within the polar circle, and two in the desert of Utah, several hundreds of kilometers South of Salt Lake City. The book is based on the diaries during the simulations, held by Vladimir Pletser, a physicist-engineer, who was selected to attend these simulations. It relates the details of everyday life in these Martian habitats and of the scientific and exploratory work conducted in these extreme environments in preparation for future manned missions to Mars. Through the real experiences described in the book, readers will find space explorations and living on Mars more tangible. .

  20. Influence of aerobic and anaerobic conditions on survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in Luria-Bertani broth, farm-yard manure and slurry.

    Science.gov (United States)

    Semenov, Alexander V; van Overbeek, Leo; Termorshuizen, Aad J; van Bruggen, Ariena H C

    2011-03-01

    The influence of aerobic and anaerobic conditions on the survival of the enteropathogens Escherichia coli O157:H7 and Salmonella serovar Typhimurium was investigated in microcosms with broth, cattle manure or slurry. These substrates were inoculated with a green fluorescent protein transformed strain of the enteropathogens at 10(7) cells g(-1) dry weight. Survival data was fitted to the Weibull model. The survival curves in aerobic conditions generally showed a concave curvature, while the curvature was convex in anaerobic conditions. The estimated survival times showed that E. coli O157:H7 survived significantly longer under anaerobic than under aerobic conditions. Survival ranged from approximately. 2 weeks for aerobic manure and slurry to more than six months for anaerobic manure at 16 °C. On average, in 56.3% of the samplings, the number of recovered E. coli O157:H7 cells by anaerobic incubation of Petri plates was significantly (p manure as well as between aerobic and anaerobic incubation of Petri dishes. The importance of changes in microbial community and chemical composition of manure and slurry was distinguished for the survival of E. coli O157:H7 in different oxygen conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Iron Redox Systematics of Martian Magmas

    Science.gov (United States)

    Righter, K.; Danielson, L.; Martin, A.; Pando, K.; Sutton, S.; Newville, M.

    2011-01-01

    Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite [1]. Morris et al. [1] propose that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks [2,3]. Magnetite stability in terrestrial magmas is well understood, as are the stability of FeO and Fe2O3 in terrestrial magmas [4,5]. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas we have undertaken an experimental study with two emphases. First we document the stability of magnetite with temperature and fO2 in a shergottite bulk composition. Second, we determine the FeO and Fe2O3 contents of the same shergottite bulk composition at 1 bar and variable fO2 at 1250 C, and at variable pressure. These two goals will help define not only magnetite stability, but pyroxene-melt equilibria that are also dependent upon fO2.

  2. Opportunity's Second Martian Birthday at Cape Verde

    Science.gov (United States)

    2007-01-01

    A promontory nicknamed 'Cape Verde' can be seen jutting out from the walls of Victoria Crater in this approximate true-color picture taken by the panoramic camera on NASA's Mars Exploration Rover Opportunity. The rover took this picture on martian day, or sol, 1329 (Oct. 20, 2007), more than a month after it began descending down the crater walls -- and just 9 sols shy of its second Martian birthday on sol 1338 (Oct. 29, 2007). Opportunity landed on the Red Planet on Jan. 25, 2004. That's nearly four years ago on Earth, but only two on Mars because Mars takes longer to travel around the sun than Earth. One Martian year equals 687 Earth days. The overall soft quality of the image, and the 'haze' seen in the lower right portion, are the result of scattered light from dust on the front sapphire window of the rover's camera. This view was taken using three panoramic-camera filters, admitting light with wavelengths centered at 750 nanometers (near infrared), 530 nanometers (green) and 430 nanometers (violet).

  3. Unusual Iron Redox Systematics of Martian Magmas

    Science.gov (United States)

    Danielson, L.; Righter, K.; Pando, K.; Morris, R. V.; Graff, T.; Agresti, D.; Martin, A.; Sutton, S.; Newville, M.; Lanzirotti, A.

    2012-01-01

    Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite. Morris et al. proposed that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks. Magnetite stability in terrestrial magmas is well understood, as are the stabilities of FeO and Fe2O3 in terrestrial magmas. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas, we have undertaken an experimental study with two emphases. First, we determine the FeO and Fe2O3 contents of super- and sub-liquidus glasses from a shergottite bulk composition at 1 bar to 4 GPa, and variable fO2. Second, we document the stability of magnetite with temperature and fO2 in a shergottite bulk composition.

  4. Effects of ocean acidification on shell condition and survival of Puget Sound pteropods from laboratory experiment studies from 2012-05-10 to 2012-07-12 (NODC Accession 0125008)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains laboratory experiment data that were collected to examine the effects of ocean acidification on shell condition and survival of Puget...

  5. Over-expression of the Arabidopsis proton-pyrophosphatase AVP1 enhances transplant survival, root mass, and fruit development under limiting phosphorus conditions.

    Science.gov (United States)

    Yang, Haibing; Zhang, Xiao; Gaxiola, Roberto A; Xu, Guohua; Peer, Wendy Ann; Murphy, Angus S

    2014-07-01

    Phosphorus (P), an element required for plant growth, fruit set, fruit development, and fruit ripening, can be deficient or unavailable in agricultural soils. Previously, it was shown that over-expression of a proton-pyrophosphatase gene AVP1/AVP1D (AVP1DOX) in Arabidopsis, rice, and tomato resulted in the enhancement of root branching and overall mass with the result of increased mineral P acquisition. However, although AVP1 over-expression also increased shoot biomass in Arabidopsis, this effect was not observed in tomato under phosphate-sufficient conditions. AVP1DOX tomato plants exhibited increased rootward auxin transport and root acidification compared with control plants. AVP1DOX tomato plants were analysed in detail under limiting P conditions in greenhouse and field trials. AVP1DOX plants produced 25% (P=0.001) more marketable ripened fruit per plant under P-deficient conditions compared with the controls. Further, under low phosphate conditions, AVP1DOX plants displayed increased phosphate transport from leaf (source) to fruit (sink) compared to controls. AVP1DOX plants also showed an 11% increase in transplant survival (P<0.01) in both greenhouse and field trials compared with the control plants. These results suggest that selection of tomato cultivars for increased proton pyrophosphatase gene expression could be useful when selecting for cultivars to be grown on marginal soils. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  6. Martian meteorites and Martian magnetic anomalies: a new perspective from NWA 7034 (Invited)

    Science.gov (United States)

    Gattacceca, J.; Rochette, P.; Scozelli, R. B.; Munayco, P.; Agee, C. B.; Quesnel, Y.; Cournede, C.; Geissman, J. W.

    2013-12-01

    The magnetic anomalies observed above the Martian Noachian crust [1] require strong crustal remanent magnetization in the 15-60 A/m range over a thickness of 20-50 km [2,3]. The Martian rocks available for study in the form of meteorites do contain magnetic minerals (magnetite and/or pyrrhotite) but in too small amount to account for such strong remanent magnetizations [4]. Even though this contradiction was easily explained by the fact that Martian meteorites (mostly nakhlites and shergottites) are not representative of the Noachian Martian crust, we were left with no satisfactory candidate lithology to account for the Martian magnetic anomalies. The discovery in the Sahara of a new type of Martian meteorite (NWA 7034 [5] and subsequent paired stones which are hydrothermalized volcanic breccia) shed a new light on this question as it contains a much larger amount of ferromagnetic minerals than any other Martian meteorite. We present here a study of the magnetic properties of NWA 7034, together with a review of the magnetic properties of thirty other Martian meteorites. Magnetic measurements (including high and low temperature behavior and Mössbauer spectroscopy) show that NWA 7034 contains about 15 wt.% of magnetite with various degrees of substitution and maghemitization up to pure maghemite, in the pseudo-single domain size range. Pyrrhotite, a common mineral in other Martian meteorites is not detected. Although it is superparamagnetic and cannot carry remanent magnetization, nanophase goethite is present in significant amounts confirming that NWA 7034 is the most oxidized Martian meteorite studied so far, as already indicated by the presence of maghemite (this study) and pyrite [5]. These magnetic properties show that a kilometric layer of a lithology similar to NWA 7034 magnetized in a dynamo field would be enough to account for the strongest Martian magnetic anomalies. Although the petrogenesis of NWA 7034 is still debated, as the brecciation could be either

  7. AN AUTOMATIZED IN-PLACE ANALYSIS OF A HEAVY LIFT JACK-UP VESSEL UNDER SURVIVAL CONDITIONS

    Directory of Open Access Journals (Sweden)

    Gil Rama

    2014-08-01

    Full Text Available Heavy lift jack-up vessels (HLJV are used for the installation of components of large offshore wind farms. A systematic FE-analysis is presented for the HLJV THOR (owned by Hochtief Infrastructure GmbH under extreme weather conditions. A parametric finite element (FE model and analysis are developed by using ANSYS-APDL programming environment. The analysis contains static and dynamic nonlinear FE-calculations, which are carried out according to the relevant standards (ISO 19905 for in-place analyses of jack-up vessels. Besides strategies of model abstraction, a guide for the determination of the relevant loads is given. In order to calculate the dynamic loads, single degree of freedom (SDOF analogy and dynamic nonlinear FE-calculations are used. As a result of detailed determination of dynamic loads and consideration of soil properties by spring elements, the used capacities are able to be reduced by 28 %. This provides for significant improvement of the environmental restrictions of the HLJV THOR for the considered load scenario.

  8. Martian Magmatic-Driven Hydrothermal Sites: Potential Sources of Energy, Water, and Life

    Science.gov (United States)

    Anderson, R. C.; Dohm, J. M.; Baker, V. R.; Ferris, J. C.; Hare, T. M.; Tanaka, K. L.; Klemaszewski, J. E.; Skinner, J. A.; Scott, D. H.

    2000-01-01

    Magmatic-driven processes and impact events dominate the geologic record of Mars. Such recorded geologic activity coupled with significant evidence of past and present-day water/ice, above and below the martian surface, indicate that hydrothermal environments certainly existed in the past and may exist today. The identification of such environments, especially long-lived magmatic-driven hydrothermal environments, provides NASA with significant target sites for future sample return missions, since they (1) could favor the development and sustenance of life, (2) may comprise a large variety of exotic mineral assemblages, and (3) could potentially contain water/ice reservoirs for future Mars-related human activities. If life developed on Mars, the fossil record would presumably be at its greatest concentration and diversity in environments where long-term energy sources and water coexisted such as at sites where long-lived, magmatic-driven hydrothermal activity occurred. These assertions are supported by terrestrial analogs. Small, single-celled creatures (prokaryotes) are vitally important in the evolution of the Earth; these prokaryotes are environmentally tough and tolerant of environmental extremes of pH, temperature, salinity, and anoxic conditions found around hydrothermal vents. In addition, there is a great ability for bacteria to survive long periods of geologic time in extreme conditions, including high temperature hydrogen sulfide and sulfur erupted from Mount St. Helens volcano. Our team of investigators is conducting a geological investigation using multiple mission-derived datasets (e.g., existing geologic map data, MOC imagery, MOLA, TES image data, geophysical data, etc.) to identify prime target sites of hydrothermal activity for future hydrological, mineralogical, and biological investigations. The identification of these sites will enhance the probability of success for future missions to Mars.

  9. Biological life support systems for martian missions: some problems and prospects

    Science.gov (United States)

    Tikhomirov, A. A.; Ushakova, S. A.; Kovaleva, N. P.; Lasseur, C.

    Taking into account the experience of scientific researches obtained during experiments in the BIOS - 3 of the Institute of Biophysics of Siberian Branch of Russian Academy of Science (IBP SB RAS) and the MELISSA program (ESA), approaches in creation biological life support systems for a flight period and a fixed-site base of Martian mission are considered. Various alternate variants of designing of elements of BLSS based on use of Chlorella and/or Spirulina, and also greenhouses with higher plants for the flight period of Martian mission are analyzed. For this purpose construction of BLSS ensuring full closure of matter turnover according to gas exchange and water and partial closure on the human's exometabolites is supposed. For the fixed site Martian station BLSS based on use of higher plants with a various degree of closure of internal mass exchange are suggested. Various versions of BLSS configuration and degree of closure of mass exchange depending on duration of Martian mission, the diet type of a crew and some other conditions are considered. Special attention is given to problems of reliability and tolerance of matter turnover processes in BLSS which maintenance is connected, in particular, with additional oxygen reproduction inside a system. Technologies for realization of BLSS of various configurations are offered and justified. The auxiliary role of the physicochemical methods in BLSS functioning both for the flight period and for the crew stay on Mars is justified.

  10. conditions

    Directory of Open Access Journals (Sweden)

    M. Venkatesulu

    1996-01-01

    Full Text Available Solutions of initial value problems associated with a pair of ordinary differential systems (L1,L2 defined on two adjacent intervals I1 and I2 and satisfying certain interface-spatial conditions at the common end (interface point are studied.

  11. Lunar and Planetary Science XXXV: Martian Meteorites: Chemical Weathering

    Science.gov (United States)

    2004-01-01

    The session "Martian Meteorites: Chemical Weathering" included the following reports:Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001; Synchrotron X-Ray Diffraction Analysis of Meteorites in Thin Section: Preliminary Results; A Survey of Olivine Alteration Products Using Raman Spectroscopy; and Rb-Sr and Sm-Nd Isotope Systematics of Shergottite NWA 856: Crystallization Age and Implications for Alteration of Hot Desert SNC Meteorites.

  12. Leaf Photosynthesis and Respiration of High CO2-Grown Tobacco Plants Selected for Survival under CO2 Compensation Point Conditions 1

    Science.gov (United States)

    Delgado, Esteban; Azcón-Bieto, Joaquim; Aranda, Xavier; Palazón, Javier; Medrano, Hipólito

    1992-01-01

    Four self-pollinated, doubled-haploid tobacco, (Nicotiana tabacum L.) lines (SP422, SP432, SP435, and SP451), selected as haploids by survival in a low CO2 atmosphere, and the parental cv Wisconsin-38 were grown from seed in a growth room kept at high CO2 levels (600-700 parts per million). The selected plants were much larger (especially SP422, SP432, and SP451) than Wisconsin-38 nine weeks after planting. The specific leaf dry weight and the carbon (but not nitrogen and sulfur) content per unit area were also higher in the selected plants. However, the chlorophyll, carotenoid, and alkaloid contents and the chlorophyll a/b ratio varied little. The net CO2 assimilation rate per unit area measured in the growth room at high CO2 was not higher in the selected plants. The CO2 assimilation rate versus intercellular CO2 curve and the CO2 compensation point showed no substantial differences among the different lines, even though these plants were selected for survival under CO2 compensation point conditions. Adult leaf respiration rates were similar when expressed per unit area but were lower in the selected lines when expressed per unit dry weight. Leaf respiration rates were negatively correlated with specific leaf dry weight and with the carbon content per unit area and were positively correlated with nitrogen and sulfur content of the dry matter. The alternative pathway was not involved in respiration in the dark in these leaves. The better carbon economy of tobacco lines selected for low CO2 survival was not apparently related to an improvement of photosynthesis rate but could be related, at least partially, to a significantly reduced respiration (mainly cytochrome pathway) rate per unit carbon. ImagesFigure 1 PMID:16668769

  13. Prognostic model for advanced breast carcinoma with luminal subtype and impact of hormonal maintenance: Implications for post-progression and conditional survival.

    Science.gov (United States)

    Carbognin, Luisa; Sperduti, Isabella; Ciccarese, Mariangela; Fabi, Alessandra; Petrucelli, Luciana; Vari, Sabrina; Forcignanò, Rosa Chiara; Nortilli, Rolando; Vicentini, Cecilia; Pilotto, Sara; Merler, Sara; Zampiva, Ilaria; Brunelli, Matteo; Manfrin, Erminia; Giannarelli, Diana; Tortora, Giampaolo; Bria, Emilio

    2016-10-01

    The aim of this analysis was to develop and validate a prognostic model for advanced breast cancer (ABC) with luminal subtype based on the combination of clinical, pathological and therapeutic predictors to provide a practical tool to evaluate patients' prognosis. Clinical and pathological data were retrospectively correlated to progression-free and overall survival (PFS/OS) using a Cox model. Significant treatment variables were adjusted with the propensity score analysis. A continuous score to identify risk classes was derived according to model ratios. The performance of the risk-class model was tested for post-progression survival (PPS) and conditional survival (CS) as well. Data from 335 patients (3 institutions) were gathered (median follow-up 58 months). At multivariate analysis Ki67, Performance Status (PS) and number of metastatic sites were significant predictors for PFS, whereas Ki67, PS, brain metastases, PFS after 1st-line therapy, number of chemotherapy lines, hormonal therapy and maintenance were significant predictors for OS. The hormonal maintenance resulted to be prognostic after adjustment with propensity score analysis. A two-class model significantly differentiated low-risk and high-risk patients for 2-year PFS (31.5% and 11.0%, p model separated low risk, intermediate-risk, and high-risk patients for 2-year PFS (40.8%, 24.4%, and 11.0%, p models equally discriminate the luminal ABC prognosis in terms of PPS and CS. A risk stratification model including 'easy-to-obtain' clinical, pathological and therapeutic parameters accurately separates luminal ABC patients into different risk classes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Magnesium isotope systematics in Martian meteorites

    Science.gov (United States)

    Magna, Tomáš; Hu, Yan; Teng, Fang-Zhen; Mezger, Klaus

    2017-09-01

    Magnesium isotope compositions are reported for a suite of Martian meteorites that span the range of petrological and geochemical types recognized to date for Mars, including crustal breccia Northwest Africa (NWA) 7034. The δ26Mg values (per mil units relative to DSM-3 reference material) range from -0.32 to -0.11‰; basaltic shergottites and nakhlites lie to the heavier end of the Mg isotope range whereas olivine-phyric, olivine-orthopyroxene-phyric and lherzolitic shergottites, and chassignites have slightly lighter Mg isotope compositions, attesting to modest correlation of Mg isotopes and petrology of the samples. Slightly heavier Mg isotope compositions found for surface-related materials (NWA 7034, black glass fraction of the Tissint shergottite fall; δ26Mg > -0.17‰) indicate measurable Mg isotope difference between the Martian mantle and crust but the true extent of Mg isotope fractionation for Martian surface materials remains unconstrained. The range of δ26Mg values from -0.19 to -0.11‰ in nakhlites is most likely due to accumulation of clinopyroxene during petrogenesis rather than garnet fractionation in the source or assimilation of surface material modified at low temperatures. The rather restricted range in Mg isotope compositions between spatially and temporally distinct mantle-derived samples supports the idea of inefficient/absent major tectonic cycles on Mars, which would include plate tectonics and large-scale recycling of isotopically fractionated surface materials back into the Martian mantle. The cumulative δ26Mg value of Martian samples, which are not influenced by late-stage alteration processes and/or crust-mantle interactions, is - 0.271 ± 0.040 ‰ (2SD) and is considered to reflect δ26Mg value of the Bulk Silicate Mars. This value is robust taking into account the range of lithologies involved in this estimate. It also attests to the lack of the Mg isotope variability reported for the inner Solar System bodies at current

  15. A First Look at Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric C02 by the Phoenix Lander

    Science.gov (United States)

    Niles, P.B.; Ming, D.W.; Boynton, W.V.; Hamara, D.; Hoffman, J.H.

    2009-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (<1%) has yet to be achieved. Given the elevated 13C values measured in carbonates in martian meteorites it has been supposed that the martian atmosphere was enriched in delta(sup 13)C. This was supported by measurements of trapped CO2 gas in EETA 79001[2] which showed elevated delta(sup 13)C values (Table 1). More recently, Earth-based spectroscopic measurements of the martian atmosphere have measured the martian CO2 to be depleted in delta(sup 13)C relative to CO2 in the terrestrial atmosphere. The spectroscopic measurements performed by Krasnopolsky et al. were reported with approx.2% uncertainties which are much smaller than the Viking measurements, but still remain very large in comparison to the magnitude of carbon and oxygen isotope fractionations under martian surface conditions. The Thermal Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander included a magnetic sector mass spectrometer (EGA) which had the goal of measuring the isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature magnetic sector instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils. Ions produced in the ion source are drawn out by a high voltage and focused by a magnetic field onto a set of collector slits. Four specific trajectories are selected to cover the mass ranges, 0.7 - 4, 7 - 35, 14 - 70, and 28 - 140 Da. Using four channels reduces the magnitude of the mass scan and provides simultaneous coverage of the mass ranges. Channel electron multiplier (CEM

  16. Ultraviolet Radiation-induced Alteration of Martian Surface Materials

    Science.gov (United States)

    Yen, A. S.

    1999-01-01

    The nature and origin of martian surface materials cannot be fully characterized without addressing the unusual reactivity of the soil and the effects of exposure to the unique martian environment. Our laboratory experiments show that ultraviolet radiation at the martian surface can result in the oxidation of metal atoms and the creation of reactive oxygen species on grain surfaces. This process is important in understanding the nature and evolution of martian soils. It can explain the reactivity discovered by the Viking Landers and possibly the origin of the ferric component of the soil.

  17. Do Martian Blueberries Have Pits? -- Artifacts of an Early Wet Mars

    Science.gov (United States)

    Lerman, L.

    2005-03-01

    Early Martian weather cycles would have supported organic chemical self-organization, the assumed predecessor to an independent "origin" of Martian life. Artifacts of these processes are discussed, including the possibility that Martian blueberries nucleated around organic cores.

  18. Mud Volcanoes of Trinidad as Astrobiological Analogs for Martian Environments

    Directory of Open Access Journals (Sweden)

    Riad Hosein

    2014-10-01

    Full Text Available Eleven onshore mud volcanoes in the southern region of Trinidad have been studied as analog habitats for possible microbial life on Mars. The profiles of the 11 mud volcanoes are presented in terms of their physical, chemical, mineralogical, and soil properties. The mud volcanoes sampled all emitted methane gas consistently at 3% volume. The average pH for the mud volcanic soil was 7.98. The average Cation Exchange Capacity (CEC was found to be 2.16 kg/mol, and the average Percentage Water Content was 34.5%. Samples from three of the volcanoes, (i Digity; (ii Piparo and (iii Devil’s Woodyard were used to culture bacterial colonies under anaerobic conditions indicating possible presence of methanogenic microorganisms. The Trinidad mud volcanoes can serve as analogs for the Martian environment due to similar geological features found extensively on Mars in Acidalia Planitia and the Arabia Terra region.

  19. Mud Volcanoes of Trinidad as Astrobiological Analogs for Martian Environments

    Science.gov (United States)

    Hosein, Riad; Haque, Shirin; Beckles, Denise M.

    2014-01-01

    Eleven onshore mud volcanoes in the southern region of Trinidad have been studied as analog habitats for possible microbial life on Mars. The profiles of the 11 mud volcanoes are presented in terms of their physical, chemical, mineralogical, and soil properties. The mud volcanoes sampled all emitted methane gas consistently at 3% volume. The average pH for the mud volcanic soil was 7.98. The average Cation Exchange Capacity (CEC) was found to be 2.16 kg/mol, and the average Percentage Water Content was 34.5%. Samples from three of the volcanoes, (i) Digity; (ii) Piparo and (iii) Devil’s Woodyard were used to culture bacterial colonies under anaerobic conditions indicating possible presence of methanogenic microorganisms. The Trinidad mud volcanoes can serve as analogs for the Martian environment due to similar geological features found extensively on Mars in Acidalia Planitia and the Arabia Terra region. PMID:25370529

  20. Human friendly architectural design for a small Martian base

    Science.gov (United States)

    Kozicki, J.; Kozicka, J.

    2011-12-01

    The manned mission to Mars is expected to last almost three years. A human factor must be taken seriously into account in such a long-term mission. A big comfortable habitat can help to overcome sociopsychological problems, that occur in ICEs (Isolated and Confined Environments). Authors have come forward to this issue and have developed a Martian base design as a human friendly habitat. The project is based on researches of extreme conditions on Mars, architecture in ICEs and contemporary building technologies. The base consists of five modules: a Central Module (CM), an Agriculture Dome (AD), a Residential Dome (RD), a Laboratory Dome (LD) and a Garage (G). Each element has its own functional purpose. The CM is a metal capsule similar to the Reference Mission module (RM, NASA, 1997). Domes are inflatable multilayer structures, which interiors are "open planned". Interiors can be arranged and divided into rooms by using modular partition walls designed by authors.

  1. The relationship between circulating natural killer cells after reduced intensity conditioning hematopoietic stem cell transplantation and relapse-free survival and graft-versus-host disease.

    Science.gov (United States)

    Dunbar, Erin M; Buzzeo, Mathew P; Levine, Jeff B; Schold, Jesse D; Meier-Kriesche, Herwig-Ulf; Reddy, Vijay

    2008-12-01

    Natural killer cells are known to have anti-tumor activity in haploidentical hematopoietic stem cell transplantation. We hypothesized that reconstituted circulating natural killer cells may be associated with improved relapse-free survival after HLA-matched hematopoietic stem cell transplantation. Serial peripheral blood absolute natural killer cell counts were prospectively measured by flow cytometry of lymphocytes expressing CD56 and CD16 in 167 patients. Cluster analysis was used at engraftment and 60 days post-transplant to distinguish patients with high and low absolute natural killer cell counts. At engraftment 80 patients had high counts (> 22.2/mm3) and 43 had low counts. At 60 days post-transplant 84 patients had high counts (> 18.2/mm3) and 38 had low counts. The primary study end-points were death, relapse and acute graft-versus-host disease. The median follow-up was 373 days (range, 67-1767). Among patients given reduced intensity conditioning, a low absolute natural killer cell count at 60 days post-transplant was independently associated with relapse [adjusted hazard ratio (AHR) = 28.4, 95% confidence interval (CI) 4.3-186.4] and death (AHR = 17.5, 95% CI 4.3-71.3). Furthermore, patients given reduced intensity conditioning who had a high absolute natural killer cell count at 60 days had a significantly better 1-year survival than those with a low count by Kaplan-Meier analysis (83% vs. 11%, pkiller count in patients given reduced intensity conditioning was independently associated with an increase in relapse or death (AHR = 20.22, 95% CI 4.76-85.40). In contrast, there was no significant association between 60-day absolute natural killer cell counts and clinical outcomes in patients receiving myeloablative conditioning. There was no significant association between absolute natural killer cell count and graft-versus-host disease. High natural killer cell reconstitution is associated with reduced relapse and death without an increased incidence of

  2. Evaluating Wharton’s Jelly-Derived Mesenchymal Stem Cell’s Survival, Migration, and Expression of Wound Repair Markers under Conditions of Ischemia-Like Stress

    Directory of Open Access Journals (Sweden)

    Iris Himal

    2017-01-01

    Full Text Available The efficacy of mesenchymal stem cell (MSC therapy is currently limited by low retention and poor survival of transplanted cells as demonstrated by clinical studies. This is mainly due to the harsh microenvironment created by oxygen and nutrient deprivation and inflammation at the injured sites. The choice of MSC source could be critical in determining fate and cellular function of MSCs under stress. Our objective here was to investigate the influence of ischemia-like stress on Wharton’s jelly MSCs (WJ-MSCs from human umbilical cord to assess their therapeutic relevance in ischemic diseases. We simulated conditions of ischemia in vitro by culturing WJ-MSCs in 2% oxygen in serum deprived and low glucose medium. Under these conditions, WJ-MSCs retained viable population of greater than 80%. They expressed the characteristic MSC surface antigens at levels comparable to the control WJ-MSCs and were negative for the expression of costimulatory molecules. An upregulation of many ECM and adhesion molecules and growth and angiogenic factors contributing to wound healing and regeneration was noted in the ischemic WJ-MSC population by a PCR array. Their migration ability, however, got impaired. Our findings provide evidence that WJ-MSCs might be therapeutically beneficial and potent in healing wounds under ischemic conditions.

  3. Influence of cooling and thawing conditions and cryoprotectant concentration on frozen-thawed survival of white-naped crane (Antigone vipio) spermatozoa.

    Science.gov (United States)

    Panyaboriban, Saritvich; Pukazhenthi, Budhan; Brown, Megan E; Crowe, Chris; Lynch, Warren; Singh, Ram P; Techakumphu, Mongkol; Songsasen, Nucharin

    2016-10-01

    To assist in genetic resource management and recovery efforts of the white-naped crane (Antigone vipio), we conducted two experiments to evaluate the effect of cooling condition, thawing rate, and cryoprotectant concentration on sperm survival post-thaw. Semen was collected from four mature males during breeding season (March and April) and evaluated for volume, sperm concentration, motility, and membrane integrity. In Experiment 1, ejaculates (n = 8) were diluted with Beltsville Poultry Semen Extender (BPSE) containing 10% dimethylsulfoxide (Me2SO) and frozen using either one (average cooling rate = 2.5 °C/min) or two step (average cooling rate = 7 and 9 °C/min, respectively) cooling method. The frozen samples were thawed using one of two thawing rates: 37 °C 30 s vs. 4 °C 1 min. In Experiment 2, samples were diluted with crane semen extender containing either 6% or 10% Me2SO, frozen using two-step method and then thawed at 37 °C for 30 s. Both cooling condition (two-step > one-step) and thawing rate (37 °C 30 s > 4 °C 1 min) impacted sperm motility, progression and kinetic characteristics (P  0.05) affect plasma membrane or acrosomal integrity. Concentration of Me2SO did not impact frozen-thaw survival. We conclude that white-naped crane sperm cryopreserved using a combination of two-step cooling and thawing at 37 °C 30 s was superior to other cooling and thawing combinations regarding to sustaining sperm motility with good motility kinetics. Findings represent the first steps towards the development of effective cryopreservation protocols and establishment of a genome resource bank for this threatened species. Copyright © 2016. Published by Elsevier Inc.

  4. BIOMEX Experiment: Ultrastructural Alterations, Molecular Damage and Survival of the Fungus Cryomyces antarcticus after the Experiment Verification Tests

    Science.gov (United States)

    Pacelli, Claudia; Selbmann, Laura; Zucconi, Laura; De Vera, Jean-Pierre; Rabbow, Elke; Horneck, Gerda; de la Torre, Rosa; Onofri, Silvano

    2017-06-01

    The search for traces of extinct or extant life in extraterrestrial environments is one of the main goals for astrobiologists; due to their ability to withstand stress producing conditions, extremophiles are perfect candidates for astrobiological studies. The BIOMEX project aims to test the ability of biomolecules and cell components to preserve their stability under space and Mars-like conditions, while at the same time investigating the survival capability of microorganisms. The experiment has been launched into space and is being exposed on the EXPOSE-R2 payload, outside of the International Space Station (ISS) over a time-span of 1.5 years. Along with a number of other extremophilic microorganisms, the Antarctic cryptoendolithic black fungus Cryomyces antarcticus CCFEE 515 has been included in the experiment. Before launch, dried colonies grown on Lunar and Martian regolith analogues were exposed to vacuum, irradiation and temperature cycles in ground based experiments (EVT1 and EVT2). Cultural and molecular tests revealed that the fungus survived on rock analogues under space and simulated Martian conditions, showing only slight ultra-structural and molecular damage.

  5. The perception of verticality in lunar and Martian gravity conditions

    NARCIS (Netherlands)

    Winkel, K.N. de; Clément, G.; Groen, E.L.; Werkhoven, P.J.

    2012-01-01

    Although the mechanisms of neural adaptation to weightlessness and re-adaptation to Earth-gravity have received a lot of attention since the first human space flight, there is as yet little knowledge about how spatial orientation is affected by partial gravity, such as lunar gravity of 0.16. g or

  6. Osteoinduction and survival of osteoblasts and bone-marrow stromal cells in 3D biphasic calcium phosphate scaffolds under static and dynamic culture conditions.

    Science.gov (United States)

    Rath, Subha N; Strobel, Leonie A; Arkudas, Andreas; Beier, Justus P; Maier, Anne-Kathrin; Greil, Peter; Horch, Raymund E; Kneser, Ulrich

    2012-10-01

    In many tissue engineering approaches, the basic difference between in vitro and in vivo conditions for cells within three-dimensional (3D) constructs is the nutrition flow dynamics. To achieve comparable results in vitro, bioreactors are advised for improved cell survival, as they are able to provide a controlled flow through the scaffold. We hypothesize that a bioreactor would enhance long-term differentiation conditions of osteogenic cells in 3D scaffolds. To achieve this either primary rat osteoblasts or bone marrow stromal cells (BMSC) were implanted on uniform-sized biphasic calcium phosphate (BCP) scaffolds produced by a 3D printing method. Three types of culture conditions were applied: static culture without osteoinduction (Group A); static culture with osteoinduction (Group B); dynamic culture with osteoinduction (Group C). After 3 and 6 weeks, the scaffolds were analysed by alkaline phosphatase (ALP), dsDNA amount, SEM, fluorescent labelled live-dead assay, and real-time RT-PCR in addition to weekly alamarBlue assays. With osteoinduction, increased ALP values and calcium deposition are observed; however, under static conditions, a significant decrease in the cell number on the biomaterial is observed. Interestingly, the bioreactor system not only reversed the decreased cell numbers but also increased their differentiation potential. We conclude from this study that a continuous flow bioreactor not only preserves the number of osteogenic cells but also keeps their differentiation ability in balance providing a suitable cell-seeded scaffold product for applications in regenerative medicine. © 2012 The Authors Journal of Cellular and Molecular Medicine © 2012 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

  7. Coastal geomorphology of the Martian northern plains

    Science.gov (United States)

    Parker, Timothy J.; Gorsline, Donn S.; Saunders, Stephen R.; Pieri, David C.; Schneeberger, Dale M.

    1993-01-01

    The paper considers the question of the formation of the outflow channels and valley networks discovered on the Martian northern plains during the Mariner 9 mission. Parker and Saunders (1987) and Parker et al. (1987, 1989) data are used to describe key features common both in the lower reaches of the outflow channels and within and along the margins of the entire northern plains. It is suggested, that of the geological processes capable of producing similar morphologies on earth, lacustrine or marine deposition and subsequent periglacial modification offer the simplest and most consistent explanation for the suit of features found on Mars.

  8. Modelling the Martian CO2 Ice Clouds

    Science.gov (United States)

    Listowski, Constantino; Määttänen, A.; Montmessin, F.; Lefèvre, F.

    2012-10-01

    Martian CO2 ice cloud formation represents a rare phenomenon in the Solar System: the condensation of the main component of the atmosphere. Moreover, on Mars, condensation occurs in a rarefied atmosphere (large Knudsen numbers, Kn) that limits the growth efficiency. These clouds form in the polar winter troposphere and in the mesosphere near the equator. CO2 ice cloud modeling has turned out to be challenging: recent efforts (e.g. [1]) fail in explaining typical small sizes (80 nm-130 nm) observed for mesospheric clouds [2]. Supercold pockets (TWood, S. E., (1999), Ph.D. thesis, UCLA [6] Young, J. B., J. Geophys. Res., 36, 294-2956, 1993

  9. The Martian stratigraphy - Short review and perspectives

    Science.gov (United States)

    Masson, P. L.

    1991-04-01

    The main aspects of the Martian stratigraphy have been determined from the detailed study of Mariner 9 and Viking Orbiter images. Three major stratigraphic systems, the Noachian System, the Hesperian System, and the Amazonian System, are inferred from these studies. Stratigraphy reveals that tectonism and volcanism were widespread during two major periods (Noachian and Lower Hesperian) and became more localized during the Upper Hesperian and Amazonian periods. The transition between these two major periods occurred about 2 Gyr ago, and significant geologic activity could still be present.

  10. Pb evolution in the Martian mantle

    Science.gov (United States)

    Bellucci, J. J.; Nemchin, A. A.; Whitehouse, M. J.; Snape, J. F.; Bland, P.; Benedix, G. K.; Roszjar, J.

    2018-03-01

    The initial Pb compositions of one enriched shergottite, one intermediate shergottite, two depleted shergottites, and Nakhla have been measured by Secondary Ion Mass Spectrometry (SIMS). These values, in addition to data from previous studies using an identical analytical method performed on three enriched shergottites, ALH 84001, and Chassigny, are used to construct a unified and internally consistent model for the differentiation history of the Martian mantle and crystallization ages for Martian meteorites. The differentiation history of the shergottites and Nakhla/Chassigny are fundamentally different, which is in agreement with short-lived radiogenic isotope systematics. The initial Pb compositions of Nakhla/Chassigny are best explained by the late addition of a Pb-enriched component with a primitive, non-radiogenic composition. In contrast, the Pb isotopic compositions of the shergottite group indicate a relatively simple evolutionary history of the Martian mantle that can be modeled based on recent results from the Sm-Nd system. The shergottites have been linked to a single mantle differentiation event at 4504 Ma. Thus, the shergottite Pb isotopic model here reflects a two-stage history 1) pre-silicate differentiation (4504 Ma) and 2) post-silicate differentiation to the age of eruption (as determined by concordant radiogenic isochron ages). The μ-values (238U/204Pb) obtained for these two different stages of Pb growth are μ1 of 1.8 and a range of μ2 from 1.4-4.7, respectively. The μ1-value of 1.8 is in broad agreement with enstatite and ordinary chondrites and that proposed for proto Earth, suggesting this is the initial μ-value for inner Solar System bodies. When plotted against other source radiogenic isotopic variables (Sri, γ187Os, ε143Nd, and ε176Hf), the second stage mantle evolution range in observed mantle μ-values display excellent linear correlations (r2 > 0.85) and represent a spectrum of Martian mantle mixing-end members (depleted

  11. The trapped heavy noble gases in recently found Martian meteorites

    OpenAIRE

    Busemann, H.; Eugster, O.

    2002-01-01

    The composition of the trapped Ar, Kr, and Xe in the Martian meteorites Los Angeles, Say Al Uhaymir 005/008, and 094 is discussed and found to be consistent with a mixture of Martian mantle and atmosphere noble gases and terrestrial contamination.

  12. Effect of Microencapsulation on Survival and Stability of Bifidobacterium bifidum BB01 Exposed to Simulated Gastrointestinal Conditions and in Different Food Matrices

    Directory of Open Access Journals (Sweden)

    Chen He

    2017-06-01

    Full Text Available Bifidobacterium bifidum BB01 was microencapsulated by extrusion method with sodium alginate. This paper aimed to study the survival rate of microencapsulating Bifidobacterium bifidum BB01 in simulated gastrointestinal conditions, resistance to artificial bile salt and stability during storage. Results showed non-microencapsulated Bifidobacterium bifidum BB01 were more susceptible than microencapsulated under simulated gastrointestinal conditions, and microencapsulated Bifidobacterium bifidum BB01 exhibited a lower population reduction than free cells during exposure to simulated gastrointestinal, The enteric test showed that the microorganism cells were released from the monolayer microcapsules, double microcapsules and trilayer completely in 40min. The viable counts of monolayer microcapsules, double layer microcapsules and triple layer microcapsules decreased by nine magnitudes, four magnitude and one magnitude after 2h, respectively. Moreover, in fruit orange, pure milk and nutrition Express, the optimum storage times of free Bifidobacterium bifidum BB01, monolayer microcapsules, double layer microcapsules and triple layer microcapsules were 21 days, 21 days, 28 days and more than 35 days at 4°C, but at room temperature the optimum storage time were 7 days, 14 days, 21 days and more than 28 days, and the viable counts were maintained at 1×106 CFU g−1 or more.

  13. A Thermal Plume Model for the Martian Convective Boundary Layer

    CERN Document Server

    Colaïtis, Arnaud; Hourdin, Frédéric; Rio, Catherine; Forget, François; Millour, Ehouarn

    2013-01-01

    The Martian Planetary Boundary Layer [PBL] is a crucial component of the Martian climate system. Global Climate Models [GCMs] and Mesoscale Models [MMs] lack the resolution to predict PBL mixing which is therefore parameterized. Here we propose to adapt the "thermal plume" model, recently developed for Earth climate modeling, to Martian GCMs, MMs, and single-column models. The aim of this physically-based parameterization is to represent the effect of organized turbulent structures (updrafts and downdrafts) on the daytime PBL transport, as it is resolved in Large-Eddy Simulations [LESs]. We find that the terrestrial thermal plume model needs to be modified to satisfyingly account for deep turbulent plumes found in the Martian convective PBL. Our Martian thermal plume model qualitatively and quantitatively reproduces the thermal structure of the daytime PBL on Mars: superadiabatic near-surface layer, mixing layer, and overshoot region at PBL top. This model is coupled to surface layer parameterizations taking ...

  14. Simulation of the Martian UV radiation climate and its effect on Deinococcus radiodurans

    Science.gov (United States)

    Pogoda de La Vega, U.; Rettberg, P.

    The question of putative life on Mars has been the topic of several studies Early works had to rely on the physical data that have been gained during the 1970s with the help of the Viking missions More recently several Mars-related missions have provided numerous and more precise data to establish a realistic simulation of the Martian climate Our focus is directed at the diurnal temperature variations and the atmospheric pressure and composition the so called thermo-physical conditions which are typical for the Martian mid- and low latitudes The resistance of terrestrial microorganisms under the thermo-physical conditions on Mars was studied for the understanding and assessment of potential life processes on Mars In order to accomplish a targeted search for life on other planets e g Mars it is necessary to know the limiting physical and chemical parameters of terrestrial life Therefore the polyextremophile bacterium Deinococcus radiodurans was chosen as test organism for these investigations For the simulation studies at the Planetary and Space Simulation Facilities PSI at DLR Cologne Germany conditions that are present during the southern summer at latitude of 60 r on Mars were applied We could simulate several environmental parameters of Mars vacuum low pressure anoxic atmosphere and diurnal cycles in temperature energy-rich UV radiation as well as shielding by different Martian soil analogue materials These parameters have been applied both single and in different combinations in laboratory experiments

  15. Martian Soil Ready for Robotic Laboratory Analysis

    Science.gov (United States)

    2008-01-01

    NASA's Phoenix Mars Lander scooped up this Martian soil on the mission's 11th Martian day, or sol, after landing (June 5, 2008) as the first soil sample for delivery to the laboratory on the lander deck. The material includes a light-toned clod possibly from crusted surface of the ground, similar in appearance to clods observed near a foot of the lander. This approximately true-color view of the contents of the scoop on the Robotic Arm comes from combining separate images taken by the Robotic Arm Camera on Sol 11, using illumination by red, green and blue light-emitting diodes on the camera. The scoop loaded with this sample was poised over an open sample-delivery door of Thermal and Evolved-Gas Analyzer at the end of Sol 11, ready to be dumped into the instrument on the next sol. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  16. Electrical Breakdown in a Martian Gas Mixture

    Science.gov (United States)

    Buhler, C. R.; Calle, C. I.; Nelson, E.

    2003-01-01

    The high probability for dust interactions during Martian dust storms and dust devils combined with the cold, dry climate of Mars most likely result in airborne dust that is highly charged. On Earth, potential gradients up to 5 kV/m have been recorded and in some cases resulted in lightning. Although the Martian atmosphere is not conducive to lightning generation, it is widely believed that electrical discharge in the form of a corona occurs. In order to understand the breakdown of gases, Paschen measurements are taken which relate the minimum potential required to spark across a gap between two electrodes. The minimum potential is plotted versus the pressure-distance value for electrodes of a given geometry. For most gases, the potential decreases as the pressure decreases. For CO2, the minimum in the curve happens to be at Mars atmospheric pressures (5-7 mm Hg) for many distances and geometries. However, a very small amount (mixing gases radically changes the curve, as noted by Leach. Here, we present the first experimental results of a Paschen curve for a Mars gas mixture compared with 100% pure CO2.

  17. Mars MetNet Mission - Martian Atmospheric Observational Post Network

    Science.gov (United States)

    Hari, Ari-Matti; Haukka, Harri; Aleksashkin, Sergey; Arruego, Ignacio; Schmidt, Walter; Genzer, Maria; Vazquez, Luis; Siikonen, Timo; Palin, Matti

    2017-04-01

    accelerometer combined with a 3-axis gyrometer. The data will be sent via auxiliary beacon antenna throughout the descent phase starting shortly after separation from the spacecraft. MetNet Mission payload instruments are specially designed to operate under very low power conditions. MNL flexible solar panels provides a total of approximately 0.7-0.8 W of electric power during the daylight time. As the provided power output is insufficient to operate all instruments simultaneously they are activated sequentially according to a specially designed cyclogram table which adapts itself to the different environmental constraints. 3. Mission Status he eventual goal is to create a network of atmospheric observational posts around the Martian surface. Even if the MetNet mission is focused on the atmospheric science, the mission payload will also include additional kinds of geophysical instrumentation. The next step is the MetNet Precursor Mission that will demonstrate the technical robustness and scientific capabilities of the MetNet type of landing vehicle. Definition of the Precursor Mission and discussions on launch opportunities are currently under way. The first MetNet Science Payload Precursors have already been successfully completed, e,g, the REMS/MSL and DREAMS/Exomars-2016. The next MetNet Payload Precursors will be METEO/Exomars-2018 and MEDA/Mars-2020. The baseline program development funding exists for the next seven years. Flight unit manufacture of the payload bay takes about 18 months, and it will be commenced after the Precursor Mission has been defined. References [1] http://metnet.fmi.fi

  18. The effect of claw horn disruption lesions and body condition score at dry-off on survivability, reproductive performance, and milk production in the subsequent lactation.

    Science.gov (United States)

    Machado, V S; Caixeta, L S; McArt, J A A; Bicalho, R C

    2010-09-01

    The objective of this study was to evaluate the effects of claw horn disruption lesions (CHDL; sole ulcers and white line disease) and body condition score (BCS) at dry-off on survivability, milk production, and reproductive performance during the subsequent lactation. An observational prospective cohort study was conducted on a large commercial dairy in Cayuga County, New York, from September 2008 until January 2009. A total of 573 cows enrolled at dry-off were scored for body condition and hoof trimmed; digits were visually inspected for the presence of CHDL. The BCS data were recategorized into a 3-level variable BCS group (BCSG), with cows with BCS3 placed in BCSG 3 (n=206). Cows in BCSG 2 were 1.35 and 1.02 times more likely to conceive than cows in BCSG 1 and 3, respectively. The cull/death hazard for BCSG 1 cows was 1.55 and 1.47 times higher than for cows in BCSG 2 and BCSG 3, respectively. Milk yield for cows in BCSG 2 (44.6 kg/d, 95% CI 43.4-45.8) was significantly greater than that for cows in BCSG 1 (41.5 kg/d, 95% CI 39.8-43.3). Cows with previous lactation days openmilk>14,054 kg had a similar 1.6 times higher odds of being classified into BCSG 1. Claw horn disruption lesions were found in 24.4% of the cows (n=140) at dry-off. Cows without CHDL were 1.4 times more likely to conceive than cows with CHDL. Additionally, lesion cows were 1.7 times more likely to die or be culled than nonlesion cows. Absence of CHDL did not have a significant effect on milk yield. These findings highlight the importance of claw health and BCS at the end of lactation on future survival and performance. Copyright (c) 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  19. Biosignatures on Mars: What, Where, and How? Implications for the Search for Martian Life.

    Science.gov (United States)

    Westall, Frances; Foucher, Frédéric; Bost, Nicolas; Bertrand, Marylène; Loizeau, Damien; Vago, Jorge L; Kminek, Gerhard; Gaboyer, Frédéric; Campbell, Kathleen A; Bréhéret, Jean-Gabriel; Gautret, Pascale; Cockell, Charles S

    2015-11-01

    The search for traces of life is one of the principal objectives of Mars exploration. Central to this objective is the concept of habitability, the set of conditions that allows the appearance of life and successful establishment of microorganisms in any one location. While environmental conditions may have been conducive to the appearance of life early in martian history, habitable conditions were always heterogeneous on a spatial scale and in a geological time frame. This "punctuated" scenario of habitability would have had important consequences for the evolution of martian life, as well as for the presence and preservation of traces of life at a specific landing site. We hypothesize that, given the lack of long-term, continuous habitability, if martian life developed, it was (and may still be) chemotrophic and anaerobic. Obtaining nutrition from the same kinds of sources as early terrestrial chemotrophic life and living in the same kinds of environments, the fossilized traces of the latter serve as useful proxies for understanding the potential distribution of martian chemotrophs and their fossilized traces. Thus, comparison with analog, anaerobic, volcanic terrestrial environments (Early Archean >3.5-3.33 Ga) shows that the fossil remains of chemotrophs in such environments were common, although sparsely distributed, except in the vicinity of hydrothermal activity where nutrients were readily available. Moreover, the traces of these kinds of microorganisms can be well preserved, provided that they are rapidly mineralized and that the sediments in which they occur are rapidly cemented. We evaluate the biogenicity of these signatures by comparing them to possible abiotic features. Finally, we discuss the implications of different scenarios for life on Mars for detection by in situ exploration, ranging from its non-appearance, through preserved traces of life, to the presence of living microorganisms. Mars-Early Earth-Anaerobic chemotrophs

  20. Biosignatures on Mars: What, Where, and How? Implications for the Search for Martian Life

    Science.gov (United States)

    Foucher, Frédéric; Bost, Nicolas; Bertrand, Marylène; Loizeau, Damien; Vago, Jorge L.; Kminek, Gerhard; Gaboyer, Frédéric; Campbell, Kathleen A.; Bréhéret, Jean-Gabriel; Gautret, Pascale; Cockell, Charles S.

    2015-01-01

    Abstract The search for traces of life is one of the principal objectives of Mars exploration. Central to this objective is the concept of habitability, the set of conditions that allows the appearance of life and successful establishment of microorganisms in any one location. While environmental conditions may have been conducive to the appearance of life early in martian history, habitable conditions were always heterogeneous on a spatial scale and in a geological time frame. This “punctuated” scenario of habitability would have had important consequences for the evolution of martian life, as well as for the presence and preservation of traces of life at a specific landing site. We hypothesize that, given the lack of long-term, continuous habitability, if martian life developed, it was (and may still be) chemotrophic and anaerobic. Obtaining nutrition from the same kinds of sources as early terrestrial chemotrophic life and living in the same kinds of environments, the fossilized traces of the latter serve as useful proxies for understanding the potential distribution of martian chemotrophs and their fossilized traces. Thus, comparison with analog, anaerobic, volcanic terrestrial environments (Early Archean >3.5–3.33 Ga) shows that the fossil remains of chemotrophs in such environments were common, although sparsely distributed, except in the vicinity of hydrothermal activity where nutrients were readily available. Moreover, the traces of these kinds of microorganisms can be well preserved, provided that they are rapidly mineralized and that the sediments in which they occur are rapidly cemented. We evaluate the biogenicity of these signatures by comparing them to possible abiotic features. Finally, we discuss the implications of different scenarios for life on Mars for detection by in situ exploration, ranging from its non-appearance, through preserved traces of life, to the presence of living microorganisms. Key Words: Mars—Early Earth

  1. MN Carbonates in the Martian Meteorite Nakhla: Possible Evidence of Brine Evaporation

    Science.gov (United States)

    Bailey, J. V.; McKay, D. S.; Wentworth, S. J.

    2003-01-01

    The importance of secondary phases in martian meteorites lies in their potential to provide clues about the martian environments responsible for their formation. During this study, we analyzed a number of carbonate-bearing fracture surfaces from the Nakhla meteorite. Here we describe the physical and chemical properties of several manganese-calcium-rich siderites. Additionally, we describe a potential model for the formation and alteration of these carbonates, and we suggest constraints on the conditions responsible for their precipitation. Nakhla is an olivine-bearing clinopyroxenite with minor amounts of feldspar, FeS, and Fe oxides. Secondary mineral assemblages include vein filling clay with embedded iron oxides, a calcium sulfate, amorphous silica, chlorapatite, halite and carbonates. Bridges and Grady suggested that the carbonates in Nakhla formed from brine evaporation. Isotope studies of the Mn rich siderite are also consistent with formation from hydrothermal fluids with an upper T constraint of 170 C.

  2. Iron-phosphate glass fiber scaffolds for the hard-soft interface regeneration: the effect of fiber diameter and flow culture condition on cell survival and differentiation.

    Science.gov (United States)

    Bitar, Malak; Salih, Vehid; Knowles, Jonathan C; Lewis, Mark P

    2008-12-15

    This work investigated the further development of a well-characterized, contiguous, glass fiber system for regeneration of the hard-soft tissue interface. We evaluated the effect of fiber diameter on human osteoblasts and fibroblasts attachment and viability using ternary glass fibers of the composition 0.48 CaO-0.02 Na(2)O-0.50 P(2)O(5). Fiber diameter significantly influenced cell attachment and survival, with fibers drawn at 800 revolutions per minute found to be optimal. Using a known composition of iron-phosphate glass fibers (composition 0.46 CaO-0.01 Na(2)O-0.03 Fe(2)O(3)-0.50 P(2)O(5)), scaffolds were produced. These scaffolds were incorporated within an open laminar flow culture system to provide nutrients, oxygen, and waste perfusion throughout the culture. The design of the chamber ensured that laminar flow was present, and changes in the differentiation of both osteoblast and fibroblast seeded scaffolds were assessed using quantitative polymerase chain reaction. Our data show that osteoblast and fibroblast differentiation is unaffected or enhanced by laminar flow when compared with static culture conditions. This system can therefore be adapted to construct larger, more complex, three-dimensional iron-phosphate fiber scaffolds for tissue engineering. 2008 Wiley Periodicals, Inc.

  3. CONFLICT MANAGEMENT CRISIS THE SITUATION IN ORDER TO FORM THE PROPERTIES OF THE COMMERCIAL ORGANIZATION IN THE CONDITIONS OF MARKET: SURVIVAL

    Directory of Open Access Journals (Sweden)

    P. V. Sаmоilоv

    2015-01-01

    Full Text Available The need for conflict management in crisis poses questions about the decision of the leaders of emerging new challenges and dialogue in the team. Ignoring conflicts that arise in the collective unacceptable, because it can lead to wrong actions in the administration. Therefore, conflicts must be analyzed from the standpoint of the theory of organization, considering it as a set of relationships between organizational units. The experience of conflict resolution points to a sequence of actions for constructive management. The article discusses the strategy of effective interventions by the manager on the conflicts (personnel manager or psychologist for the purpose of settlement, and provides a sequence of structuring the conflict in block diagram form. In a crisis, the organization to minimize the time for conflict resolution is one of the most important requirements for its effective overcoming. In a crisis, the organization to minimize the time for conflict resolution is one of the most important requirements for its effective overcoming. Direction of action discussed above consultant on crisis management issues, refer to the table. The proposed approach of conflict resolution in crisis mode, considering the direction of formation of such an important organization in the commercial property market conditions as the survival rate. However, the manager of the proposed expansion of differentiated arsenal of interventions in the inevitable conflicts between organizational units.

  4. A Study of the Electrostatic Interaction Between Insulators and Martian/Lunar Soil Simulants

    Science.gov (United States)

    Mantovani, James G.

    2001-01-01

    Using our previous experience with the Mars Environmental Compatibility Assessment (MECA) electrometer, we have designed a new type of aerodynamic electrometer. The goal of the research was to measure the buildup of electrostatic surface charge on a stationary cylindrical insulator after windborne granular particles have collided with the insulator surface in a simulated dust storm. The experiments are performed inside a vacuum chamber. This allows the atmospheric composition and pressure to be controlled in order to simulate the atmospheric conditions near the equator on the Martian surface. An impeller fan was used to propel the dust particles at a cylindrically shaped insulator under low vacuum conditions. We tested the new electrometer in a 10 mbar CO2 atmosphere by exposing two types of cylindrical insulators, Teflon (1.9 cm diameter) and Fiberglass (2.5 cm diameter), to a variety of windborne granular particulate materials. The granular materials tested were JSC Mars-1 simulant, which is a mixture of coarse and fine (insulator capped planar electrode for measuring the amount of electrostatic charge produced by rubbing an insulator surface over Martian and lunar soil simulants. The results of this study indicate that it is possible to detect triboelectric charging of insulator surfaces by windborne Martian soil simulant, and by individual mineral constituents of the soil simulant. We have also found that Teflon and Fiberglass insulator surfaces respond in different ways by developing opposite polarity surface charge, which decays at different rates after the particle impacts cease.

  5. Seasonal variability of Martian ion escape through the plume and tail from MAVEN observations

    Science.gov (United States)

    Dong, Y.; Fang, X.; Brain, D. A.; McFadden, J. P.; Halekas, J. S.; Connerney, J. E. P.; Eparvier, F.; Andersson, L.; Mitchell, D.; Jakosky, B. M.

    2017-04-01

    We study the Mars Atmosphere and Volatile Evolution spacecraft observations of Martian planetary ion escape during two time periods: 11 November 2014 to 19 March 2015 and 4 June 2015 to 24 October 2015, with the focus on understanding the seasonal variability of Martian ion escape in response to the solar extreme ultraviolet (EUV) flux. We organize the >6 eV O+ ion data by the upstream electric field direction to estimate the escape rates through the plume and tail. To investigate the ion escape dependence on the solar EUV flux, we constrain the solar wind dynamic pressure and interplanetary magnetic filed strength and compare the ion escape rates through the plume and tail in different energy ranges under high and low EUV conditions. We found that the total >6 eV O+ escape rate increases from 2 to 3 × 1024 s-1 as the EUV irradiance increases by almost the same factor, mostly on the <1 keV tailward escape. The plume escape rate does not vary significantly with EUV. The relative contribution from the plume to the total escape varies between 30% and 20% from low to high EUV. Our results suggest that the Martian ion escape is sensitive to the seasonal EUV variation, and the contribution from plume escape becomes more important under low EUV conditions.

  6. Determining the source locations of martian meteorites: Hapke mixture models applied to CRISM simulated data of igneous mineral mixtures and martian meteorites

    Science.gov (United States)

    Harris, Jennifer; Grindrod, Peter

    2017-04-01

    At present, martian meteorites represent the only samples of Mars available for study in terrestrial laboratories. However, these samples have never been definitively tied to source locations on Mars, meaning that the fundamental geological context is missing. The goal of this work is to link the bulk mineralogical analyses of martian meteorites to the surface geology of Mars through spectral mixture analysis of hyperspectral imagery. Hapke radiation transfer modelling has been shown to provide accurate (within 5 - 10% absolute error) mineral abundance values from laboratory derived hyperspectral measurements of binary [1] and ternary [2] mixtures of plagioclase, pyroxene and olivine. These three minerals form the vast bulk of the SNC meteorites [3] and the bedrock of the Amazonian provinces on Mars that are inferred to be the source regions for these meteorites based on isotopic aging. Spectral unmixing through the Hapke model could be used to quantitatively analyse the Martian surface and pinpoint the exact craters from which the SNC meteorites originated. However the Hapke model is complex with numerous variables, many of which are determinable in laboratory conditions but not from remote measurements of a planetary surface. Using binary and tertiary spectral mixtures and martian meteorite spectra from the RELAB spectral library, the accuracy of Hapke abundance estimation is investigated in the face of increasing constraints and simplifications to simulate CRISM data. Constraints and simplifications include reduced spectral resolution, additional noise, unknown endmembers and unknown particle physical characteristics. CRISM operates in two spectral resolutions, the Full Resolution Targeted (FRT) with which it has imaged approximately 2% of the martian surface, and the lower spectral resolution MultiSpectral Survey mode (MSP) with which it has covered the vast majority of the surface. On resampling the RELAB spectral mixtures to these two wavelength ranges it was

  7. Soymilk residue (okara as a natural immobilization carrier for Lactobacillus plantarum cells enhances soymilk fermentation, glucosidic isoflavone bioconversion, and cell survival under simulated gastric and intestinal conditions

    Directory of Open Access Journals (Sweden)

    Xia Xiudong

    2016-11-01

    intestinal stresses in vitro that included low pH, low pH plus pepsin, pancreatin, and bile salt. Our results indicate that okara is a new potential immobilization carrier to enhance the growth and glucosidic isoflavone bioconversion activities of L. plantarum in soymilk and improve cell survivability following simulated gastric and intestinal conditions.

  8. [Growth and survival of the green mussel P. viridis (Bivalvia: Mytilidae) in bottom culture conditions in Turpialito, Golfo de Cariaco, Venezuela].

    Science.gov (United States)

    Acosta, Vanessa; Montes, Marbelis; Cortez, Roraysi; Guevara, Miguel; Lodeiros, César

    2012-12-01

    Mussels represent one of the most important mollusk species for culture activities around the world, and their growth may depend on the culture system used and locality. In this study, we evaluated the growth of Perna viridis in bottom culture to test its performance when using natural food, and to decide its use as a culture species in the Gulf of Cariaco. For this, mussel seeds (35.81 +/- 1.41 mm in length) were obtained in the locality of Guaca (North coast of Sucre state) and transferred to the Hydrobiological Station of Turpialito, Gulf of Cariaco, Sucre state, Venezuela, where they were planted in "Spanish baskets" to evaluate their growth between July 2007 and February 2008. Monthly survival was determined and the maximum shell length, dry mass of muscle and remains tissues of the gonad. The environmental parameters (water temperature, salinity, dissolved oxygen, chlorophyll a, total seston and organic fraction), in the cultivation area were determined every 15 days. Monthly measurements were made of proteins, lipids and carbohydrates to seston. During the entire study the mussels showed continued growth, ultimately reaching a maximum length of 78.7 +/- 4.43 mm. However, the growth rate of the dry mass of somatic (muscle, other tissue) and reproductive tissues showed variability throughout the study, and observed a significant increase by the end of the experiment. The observed variations in the growth rate of the reproductive tissue mass depended on the reserves accumulated and food offered by the environment. The organic seston throughout the experience showed an independence of temperature and chlorophyll a values; this one maintained values above 1 mg/L, thus forming the main food resource for mussels. The high content of proteins, lipids and carbohydrates observed in the seston at the end of the study, might be mainly associated with coastal upwelling, which provides a great food contribution of phytoplankton and organic type. The high survival rate

  9. Influence of Martian regolith analogs on the activity and growth of methanogenic archaea, with special regard to long-term desiccation

    Directory of Open Access Journals (Sweden)

    Janosch eSchirmack

    2015-03-01

    Full Text Available Methanogenic archaea have been studied as model organisms for possible life on Mars for several reasons: they can grow lithoautotrophically by using hydrogen and carbon dioxide as energy and carbon sources, respectively; they are anaerobes; and they evolved at a time when conditions on early Earth are believed to have looked similar to those of early Mars. As Mars is currently dry and cold and as water might be available only at certain time intervals, any organism living on this planet would need to cope with desiccation. On Earth there are several regions with low water availability as well, e.g. permafrost environments, desert soils and salt pans. Here, we present the results of a set of experiments investigating the influence of different Martian regolith analogs on the metabolic activity and growth of three methanogenic strains exposed to culture conditions as well as long-term desiccation. In most cases, concentrations below 1 %wt of regolith in the media resulted in an increase of methane production rates, whereas higher concentrations decreased the rates, thus prolonging the lag phase. Further experiments showed that methanogenic archaea are capable of producing methane when incubated on a water-saturated sedimentary matrix of regolith lacking nutrients. Survival of methanogens under these conditions was analyzed with a 400 day desiccation experiment in the presence of regolith analogs. All tested strains of methanogens survived the desiccation period as it was determined through reincubation on fresh medium and via qPCR following propidium monoazide treatment to identify viable cells. The survival of long-term desiccation and the ability of active metabolism on water-saturated MRAs strengthens the possibility of methanogenic archaea or physiologically similar organisms to exist in environmental niches on Mars. The best results were achieved in presence of a phyllosilicate, which provides insights of possible positive effects in habitats

  10. Evidence for a Second Martian Dynamo from Electron Reflection Magnetometry

    Science.gov (United States)

    Lillis, R. J.; Manga, M.; Mitchell, D. L.; Lin, R. P.; Acuna, M. H.

    2005-01-01

    Present-day Mars does not possess an active core dynamo and associated global magnetic field. However, the discovery of intensely magnetized crust in Mars Southern hemisphere implies that a Martian dynamo has existed in the past. Resolving the history of the Martian core dynamo is important for understanding the evolution of the planet's interior. Moreover, because the global magnetic field provided by an active dynamo can shield the atmosphere from erosion by the solar wind, it may have influenced past Martian climate. Additional information is included in the original extended abstract.

  11. The Martian highland paterae: Evidence for explosive volcanism on Mars

    Science.gov (United States)

    Crown, David A.; Greeley, Ronald

    1988-01-01

    The Martian surface exhibits numerous volcanic landforms displaying great diversity in size, age, and morphology. Most research regarding Martian volcanology has centered around effusive basaltic volcanism, including analyses of individual lava flows, extensive lava plains, and large shield volcanoes. These studies were hindered by a lack of definitive morphologic criteria for the remote identification of ash deposits. Knowledge of the abundances, ages, and geologic settings of explosive volcanic deposits on Mars is essential to a comprehensive understanding of the evolution of the Martian surface, with implications for the evolution of the lithosphere and atmosphere as well as the histories of specific volcanic centers and provinces.

  12. Rover's Wheel Churns Up Bright Martian Soil

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Spirit acquired this mosaic on the mission's 1,202nd Martian day, or sol (May 21, 2007), while investigating the area east of the elevated plateau known as 'Home Plate' in the 'Columbia Hills.' The mosaic shows an area of disturbed soil, nicknamed 'Gertrude Weise' by scientists, made by Spirit's stuck right front wheel. The trench exposed a patch of nearly pure silica, with the composition of opal. It could have come from either a hot-spring environment or an environment called a fumarole, in which acidic, volcanic steam rises through cracks. Either way, its formation involved water, and on Earth, both of these types of settings teem with microbial life. Spirit acquired this mosaic with the panoramic camera's 753-nanometer, 535-nanometer, and 432-nanometer filters. The view presented here is an approximately true-color rendering.

  13. Stratigraphy of the Martian northern plains

    Science.gov (United States)

    Tanaka, K. L.

    1993-01-01

    The northern plains of Mars are roughly defined as the large continuous region of lowlands that lies below Martian datum, plus higher areas within the region that were built up by volcanism, sedimentation, tectonism, and impacts. These northern lowlands span about 50 x 10(exp 6) km(sup 2) or 35 percent of the planet's surface. The age and origin of the lowlands continue to be debated by proponents of impact and tectonic explanations. Geologic mapping and topical studies indicate that volcanic, fluvial, and eolian deposition have played major roles in the infilling of this vast depression. Periglacial, glacial, fluvial, eolian, tectonic, and impact processes have locally modified the surface. Because of the northern plains' complex history of sedimentation and modification, much of their stratigraphy was obscured. Thus the stratigraphy developed is necessarily vague and provisional: it is based on various clues from within the lowlands as well as from highland areas within and bordering the plains. The results are summarized.

  14. Martian north polar cap summer water cycle

    Science.gov (United States)

    Brown, Adrian J.; Calvin, Wendy M.; Becerra, Patricio; Byrne, Shane

    2016-10-01

    A key outstanding question in Martian science is "are the polar caps gaining or losing mass and what are the implications for past, current and future climate?" To address this question, we use observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of the north polar cap during late summer for multiple Martian years, to monitor the summertime water cycle in order to place quantitative limits on the amount of water ice deposited and sublimed in late summer. We establish here for the first time the summer cycle of water ice absorption band signatures on the north polar cap. We show that in a key region in the interior of the north polar cap, the absorption band depths grow until Ls = 120, when they begin to shrink, until they are obscured at the end of summer by the north polar hood. This behavior is transferable over the entire north polar cap, where in late summer regions 'flip' from being net sublimating into net condensation mode. This transition or 'mode flip' happens earlier for regions closer to the pole, and later for regions close to the periphery of the cap. The observations and calculations presented herein estimate that on average a water ice layer ∼70 microns thick is deposited during the Ls = 135-164 period. This is far larger than the results of deposition on the south pole during summer, where an average layer 0.6-6 microns deep has been estimated by Brown et al. (2014) Earth Planet. Sci. Lett., 406, 102-109.

  15. Rituximab-containing reduced-intensity conditioning improves progression-free survival following allogeneic transplantation in B cell non-Hodgkin lymphoma

    Directory of Open Access Journals (Sweden)

    Narendranath Epperla

    2017-06-01

    Full Text Available Abstract Background In B cell non-Hodgkin lymphoma (B-NHL, rituximab-containing reduced-intensity conditioning regimens (R-RIC have been shown to provide favorable outcomes in single-arm studies; however, large multicenter studies comparing R-RIC and non-rituximab-containing reduced-intensity conditioning regimens (nonR-RIC have not been performed. Using the CIBMTR database, we report the outcomes of R-RIC versus nonR-RIC regimens in B-NHL. Methods We evaluated 1401 adult B-NHL patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT who received nonR-RIC (n = 1022 or R-RIC (n = 379 regimens. Graft-versus-host disease (GVHD prophylaxis was limited to calcineurin inhibitor-based approaches. Results Median follow-up of survivors in the R-RIC and nonR-RIC groups was 47 and 37 months, respectively. On multivariate analysis, no difference was seen between the R-RIC and nonR-RIC cohorts in terms of acute GVHD grade II–IV (RR = 1.14, 95%CI = 0.83–1.56, p = 0.43 or grade III–IV (RR = 1.16, 95%CI = 0.72–1.89, p = 0.54, chronic GVHD (RR = 1.15, 95%CI = 0.92–1.46, p = 0.22, non-relapse mortality (RR = 0.90; 95%CI = 0.67–1.22; p = 0.51, relapse/progression (RR = 0.79; 95%CI = 0.63–1.01; p = 0.055, and mortality (RR = 0.84, 95%CI = 0.69–1.02, p = 0.08 risk. However, R-RIC was associated with a significantly improved progression-free survival (RR = 0.76; 95%CI 0.62–0.92; p = 0.006. On subgroup analysis, mortality benefit was noted in the R-RIC group patients not receiving busulfan-based RIC (RR = 0.76; 95%CI = 0.60–0.96; p = 0.02 and with the use of a higher cumulative rituximab dose (RR = 0.43; 95%CI = 0.21–0.90; p = 0.02. Conclusion Our analysis shows that inclusion of rituximab in RIC regimens improves progression-free survival in patients with B cell NHL. These data supports the use of R-RIC in B

  16. Shared Frailty Model for Left-Truncated Multivariate Survival Data

    DEFF Research Database (Denmark)

    Jensen, Henrik; Brookmeyer, Ron; Aaby, Peter

    multivariate survival data, left truncation, multiplicative hazard model, shared gamma frailty, conditional model, piecewise exponential model, childhood survival......multivariate survival data, left truncation, multiplicative hazard model, shared gamma frailty, conditional model, piecewise exponential model, childhood survival...

  17. Experimental infection of the endangered bonytail chub (Gila elegans) with the Asian fish tapeworm (Bothriocephalus acheilognathi): impacts on survival, growth, and condition

    Science.gov (United States)

    Hansen, S.P.; Choudhury, A.; Heisey, D.M.; Ahumada, J.A.; Hoffnagle, T.L.; Cole, R.A.

    2006-01-01

    Bothriocephalus acheilognathi Yamaguti, 1934, a tapeworm known to be pathogenic to some fish species, has become established in the endangered humpback chub (Gila cypha Miller, 1964) in Grand Canyon, USA, following the tapeworm's introduction into the Colorado River system. The potential impact of this tapeworm on humpback chub was studied by exposing the closely related bonytail chub (Gila elegans Baird and Girard, 1853) to the parasite under a range of conditions that included potential stressors of humpback chub in their natal waters, such as abrupt temperature change and a limited food base. Survival of infected fish under low food rations was considerably lower than that of control fish, and mortality of infected fish began 20days earlier. Growth of infected fish was significantly reduced, and negative changes in health condition indices were found. No significant negative impacts were revealed from the synergistic effects between temperature shock and infection. Bothriocephalus acheilognathi does present a potential threat to humpback chub in Grand Canyon and should be considered, along with conventional concerns involving altered flow regimes and predation, when management decisions are made concerning conservation of this endangered species.// Bothriocephalus acheilognathi Yamaguti, 1934, un ver plat connu comme pathog??ne pour certaines esp??ces de poissons, s'est associ?? au A (Gila cypha Miller, 1964), une esp??ce menac??e du Grand Canyon, ??.-U., apr??s l'introduction du ver dans le r??seau hydrographique du Colorado. Nous avons ??tudi?? l'impact potentiel de ce ver plat sur le m??n?? bossu en exposant l'esp??ce proche Gila elegans Baird et Girard, 1853 au parasite sous une gamme de conditions qui incluent les facteurs potentiels de stress des m??n??s bossus dans leurs cours d'eau d'origine, tels que les changements abrupts de temp??rature et des ressources alimentaires limit??es. La survie des poissons infect??s dans des conditions de nourriture limit

  18. Enterococcus faecium and Enterococcus durans isolated from cheese: Survival in the presence of medications under simulated gastrointestinal conditions and adhesion properties.

    Science.gov (United States)

    Amaral, Daniel M F; Silva, Luana F; Casarotti, Sabrina N; Nascimento, Liane Caroline Sousa; Penna, Ana Lúcia B

    2017-02-01

    In this study, we evaluated the survival of Enterococcus faecium and Enterococcus durans, isolated from cheese, in the presence of medications and under simulated in vitro gastrointestinal conditions. The presence of genes encoding virulence factors, the susceptibility to antimicrobial agents, and adhesion properties were also assessed. Enterococcus faecium and E. durans both exhibited resistance to most of the tested medications but showed a large sensitivity to analgesics and antihypertensives; they also showed wide susceptibility to antimicrobial agents. Enterococcus durans SJRP29 had greater resistance to the presence of medications in comparison with the probiotic Lactobacillus acidophilus La-5. The strains, except for E. durans SJRP05, did not harbor virulence genes. Enterococcus durans SJRP14, SJRP17, and SJRP26 were sensitive to all tested antimicrobial agents. Enterococcus faecium was more stable during the simulation of gastrointestinal tract and showed greater viability. At the end of the assay, except for E. durans SJRP17, all strains showed high viability (>7 log cfu/mL). Enterococcus durans SJRP29 stood out from the other strains and was selected for further evaluation; it tolerated up to 3.0% NaCl at 30 and 37°C, besides having good adhesion properties (high values of auto-aggregation, co-aggregation, and hydrophobicity). Additionally, the microorganism did not show bile salt hydrolase activity or mucin degradation. These results encourage carrying out additional tests to evaluate the probiotic features by using in vitro dynamic models and in vivo tests before applying these strains to a food system. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  19. Physical abrasion of mafic minerals and basalt grains: application to Martian aeolian deposits

    Science.gov (United States)

    Cornwall, Carin; Bandfield, Joshua L.; Titus, Timothy N.; Schreiber, B. C.; Montgomery, D.R.

    2015-01-01

    Sediment maturity, or the mineralogical and physical characterization of sediment deposits, has been used to locate sediment source, transport medium and distance, weathering processes, and paleoenvironments on Earth. Mature terrestrial sands are dominated by quartz, which is abundant in source lithologies on Earth and is physically and chemically stable under a wide range of conditions. Immature sands, such as those rich in feldspars or mafic minerals, are composed of grains that are easily physically weathered and highly susceptible to chemical weathering. On Mars, which is predominately mafic in composition, terrestrial standards of sediment maturity are not applicable. In addition, the martian climate today is cold, dry and sediments are likely to be heavily influenced by physical weathering rather than chemical weathering. Due to these large differences in weathering processes and composition, martian sediments require an alternate maturity index. Abrason tests have been conducted on a variety of mafic materials and results suggest that mature martian sediments may be composed of well sorted, well rounded, spherical basalt grains. In addition, any volcanic glass present is likely to persist in a mechanical weathering environment while chemically altered products are likely to be winnowed away. A modified sediment maturity index is proposed that can be used in future studies to constrain sediment source, paleoclimate, mechanisms for sediment production, and surface evolution. This maturity index may also provide details about erosional and sediment transport systems and preservation processes of layered deposits.

  20. The spectroscopic chemical and photophysical properties of Martian soils and their analogs

    Science.gov (United States)

    Coyne, Lelia M.

    1987-01-01

    The program of research outlined should advance significantly the understanding of the spectral signal of montmorillonites in general and the variations produced in it by structural and surface ferric and ferrous iron and interlayer water as a function of several environmental conditions that are different between Earth and Mars. In addition, an extensive data base was collected providing spectral characterization of several features (iron, both surface and structural, OH-groups, both structural and from adsorbed water and O(-) centers) that are known, or thought to be, influential in directing the surface activity of these important materials. With this data base with which to assess the results of the Viking labeled release simulation studies, it should be possible to gain important insights into the mechanisms of surface reactivity for this important chemical reaction. The results to be gained from these studies will provide a significant body of ground base truth from which to assess: the presence of smectite clays on Mars; the mineralogical form in which the Martian iron is bound; establish upper limits on the present surface water content of Martian soils; perhaps provide insights on the Martian surface radiation history; and to make strong predictions about the nature of surface chemistry on Mars, if iron-bearing clays are a significant component of the surface mineralogical assemblage.

  1. Effect of particle size of Martian dust on the degradation of photovoltaic cell performance

    Science.gov (United States)

    Gaier, James R.; Perez-Davis, Marla E.

    1991-01-01

    Glass coverglass and SiO2 covered and uncovered silicon photovoltaic (PV) cells were subjected to conditions simulating a Mars dust storm, using the Martian Surface Wind Tunnel, to assess the effect of particle size on the performance of PV cells in the Martian environment. The dust used was an artificial mineral of the approximate elemental composition of Martian soil, which was sorted into four different size ranges. Samples were tested both initially clean and initially dusted. The samples were exposed to clear and dust laden winds, wind velocities varying from 23 to 116 m/s, and attack angles from 0 to 90 deg. It was found that transmittance through the coverglass approximates the power produced by a dusty PV cell. Occultation by the dust was found to dominate the performance degradation for wind velocities below 50 m/s, whereas abrasion dominates the degradation at wind velocities above 85 m/s. Occultation is most severe at 0 deg (parallel to the wind), is less pronounced from 22.5 to 67.5 deg, and is somewhat larger at 90 deg (perpendicular to the wind). Abrasion is negligible at 0 deg, and increases to a maximum at 90 deg. Occultation is more of a problem with small particles, whereas large particles (unless they are agglomerates) cause more abrasion.

  2. Suprathermal oxygen atoms in the Martian upper atmosphere: Contribution of the proton and hydrogen atom precipitation

    Science.gov (United States)

    Shematovich, V. I.

    2017-07-01

    This is a study of the kinetics and transport of hot oxygen atoms in the transition region (from the thermosphere to the exosphere) of the Martian upper atmosphere. It is assumed that the source of the hot oxygen atoms is the transfer of momentum and energy in elastic collisions between thermal atmospheric oxygen atoms and the high-energy protons and hydrogen atoms precipitating onto the Martian upper atmosphere from the solar-wind plasma. The distribution functions of suprathermal oxygen atoms by the kinetic energy are calculated. It is shown that the exosphere is populated by a large number of suprathermal oxygen atoms with kinetic energies up to the escape energy 2 eV; i.e., a hot oxygen corona is formed around Mars. The transfer of energy from the precipitating solar-wind plasma protons and hydrogen atoms to the thermal oxygen atoms leads to the formation of an additional nonthermal escape flux of atomic oxygen from the Martian atmosphere. The precipitation-induced escape flux of hot oxygen atoms may become dominant under the conditions of extreme solar events, such as solar flares and coronal mass ejections, as shown by recent observations onboard NASA's MAVEN spacecraft (Jakosky et al., 2015).

  3. Hematite Mineralized Bacterial Remnants: Implications for Martian Hematite Deposits

    Science.gov (United States)

    Schelble, Rachel T.; Westall, Frances; Allen, Carlton C.; Brearley, Adrian J.

    2001-01-01

    Hematite mineralized bacterial remnants in the Gunflint Formation [early Proterozoic] can be used as an analog for potential microfossils in martian iron deposits. Additional information is contained in the original extended abstract.

  4. The martian photoelectron boundary as seen by MAVEN

    Science.gov (United States)

    Garnier, P.; Steckiewicz, M.; Mazelle, C.; Xu, S.; Mitchell, D.; Holmberg, M. K. G.; Halekas, J. S.; Andersson, L.; Brain, D. A.; Espley, J. R.; Lillis, R. J.; Luhmann, J. G.; Sauvaud, J.-A.; Jakosky, B. M.

    2017-09-01

    We analyze here in details the location, drivers, properties, and implications for escape of the martian photoelectron boundary based on the Mars Atmosphere and Volatile Evolution (MAVEN) data obtained from September 2014 until May 2016.

  5. Evidence for explosive volcanic density currents on certain Martian volcanoes

    Science.gov (United States)

    Reimers, C. E.; Komar, P. D.

    1979-01-01

    The morphologies of certain of the smaller Martian volcanoes are discussed as possible results of explosive volcanic density currents. An examination of newly-photographed flank and caldera features of the Martian volcanoes Ceraunius Tholus, Uranius Tholus, Uranius Patera and Hecates Tholus, including steep slope angles, Krakatoa-type caldera morphologies, erosional features (radial channels and anastamosing gullies) and constructional features (blanketed flanks and possible lava deltas) reveals their similarity to terrestrial cones and composite volcanoes such as Barcena Volcano. Crater age data from the surface of Martian domes and shields indicates that such explosive activity occurred more frequently early in Martian geologic history, consistent with the view that the volcanic density currents were base surges rather than nuees ardentes, with the melting of permafrost supplying the water required in base surge generation.

  6. Plasma Catalytic Extraction of Oxygen from the Martian Atmosphere Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Plasma catalytic techniques are proposed for the extraction of oxygen from the abundant carbon dioxide contained in the Martian atmosphere (95% CO2).. The Phase I...

  7. Plasma Extraction of Oxygen from Martian Atmosphere Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Plasma techniques are proposed for the extraction of oxygen from the abundant carbon dioxide contained in the Martian atmosphere (96 % CO2). In this process, CO2 is...

  8. Effects of Rocks on Martian Ground Ice and Neutron Flux

    Science.gov (United States)

    Sizemore, H. G.; Mellon, M. T.

    2005-03-01

    We present numerical simulations of the three-dimensional distribution of ground ice in a heterogeneous martian soil and discuss the implications of our results for the interpretation of Mars Odyssey Gamma Ray Spectrometer data.

  9. VCHP Radiators for Lunar and Martian Environments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-term Lunar and Martian systems present challenges to thermal systems, including changes in thermal load, and large changes in the thermal environment between...

  10. VCHP Radiators for Lunar and Martian Environments Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-term Lunar and Martian systems present challenges to thermal control systems, including changes in thermal load, and large changes in the thermal environment...

  11. Mobility of icy sand packs, with application to Martian permafrost

    Science.gov (United States)

    Durham, W.B.; Pathare, A.V.; Stern, L.A.; Lenferink, H.J.

    2009-01-01

    [1] The physical state of water on Mars has fundamental ramifications for both climatology and astrobiology. The widespread presence of "softened" Martian landforms (such as impact craters) can be attributed to viscous creep of subsurface ground ice. We present laboratory experiments designed to determine the minimum amount of ice necessary to mobilize topography within Martian permafrost. Our results show that the jammed-to-mobile transition of icy sand packs neither occurs at fixed ice content nor is dependent on temperature or stress, but instead correlates strongly with the maximum dry packing density of the sand component. Viscosity also changes rapidly near the mobility transition. The results suggest a potentially lower minimum volatile inventory for the impact-pulverized megaregolith of Mars. Furthermore, the long-term preservation of partially relaxed craters implies that the ice content of Martian permafrost has remained close to that at the mobility transition throughout Martian history. Copyright 2009 by the American Geophysical Union.

  12. Physical Analog Modeling of Martian Dike-Induced Deformation

    Science.gov (United States)

    Wyrick, D. Y.; Watson-Morris, M. J.; Morris, A. P.

    2012-03-01

    Analog models of dike injection were performed to determine style and magnitude of structural deformation associated with the dike. Primary deformation style is contraction rather than extension, indicating that martian dikes may not create grabens.

  13. Larval food quantity affects development time, survival and adult biological traits that influence the vectorial capacity of Anopheles darlingi under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Araújo Maisa

    2012-08-01

    Full Text Available Abstract Background The incidence of malaria in the Amazon is seasonal and mosquito vectorial capacity parameters, including abundance and longevity, depend on quantitative and qualitative aspects of the larval diet. Anopheles darlingi is a major malaria vector in the Amazon, representing >95% of total Anopheles population present in the Porto Velho region. Despite its importance in the transmission of the Plasmodium parasite, knowledge of the larval biology and ecology is limited. Studies regarding aspects of adult population ecology are more common than studies on larval ecology. However, in order develop effective control strategies and laboratory breeding conditions for this species, more data on the factors affecting vector biology is needed. The aim of the present study is to assess the effects of larval food quantity on the vectorial capacity of An. darling under laboratory conditions. Methods Anopheles darlingi was maintained at 28°C, 80% humidity and exposed to a daily photoperiod of 12 h. Larvae were divided into three experimental groups that were fed either a low, medium, or high food supply (based on the food amounts consumed by other species of culicids. Each experiment was replicated for six times. A cohort of adults were also exposed to each type of diet and assessed for several biological characteristics (e.g. longevity, bite frequency and survivorship, which were used to estimate the vectorial capacity of each experimental group. Results The group supplied with higher food amounts observed a reduction in development time while larval survival increased. In addition to enhanced longevity, increasing larval food quantity was positively correlated with increasing frequency of bites, longer blood meal duration and wing length, resulting in greater vectorial capacity. However, females had greater longevity than males despite having smaller wings. Conclusions Overall, several larval and adult biological traits were significantly

  14. Thermal and hydraulic considerations regarding the fate of water discharged by the outflow channels to the Martian northern plains

    Science.gov (United States)

    Clifford, S. M.

    1993-01-01

    The identification of possible shorelines in the Martian northern plains suggests that the water discharged by the circum-Chryse outflow channels may have led to the formation of transient seas, or possibly even an ocean, covering as much as one-third of the planet. Speculations regarding the possible fate of this water have included local ponding and reinfiltration into the crust; freezing, sublimation, and eventual cold-trapping at higher latitudes; or the in situ survival of this now frozen water to the present day -- perhaps aided by burial beneath a protective cover of eolian sediment or lavas. Although neither cold-trapping at higher latitudes nor the subsequent freezing and burial of flood waters can be ruled out, thermal and hydraulic considerations effectively eliminate the possibility that any significant reassimilation of this water by local infiltration has occurred given climatic conditions resembling those of today. The arguments against the local infiltration of flood water into the northern plains are two-fold. First, given the climatic and geothermal conditions that are thought to have prevailed on Mars during the Late Hesperian (the period of peak outflow channel activity in the northern plains), the thickness of the cryosphere in Chryse Planitia is likely to have exceeded 1 km. A necessary precondition for the widespread occurrence of groundwater is that the thermodynamic sink represented by the cryosphere must already be saturated with ice. For this reason, the ice-saturated cryosphere acts as an impermeable barrier that effectively precludes the local resupply of subpermafrost groundwater by the infiltration of water discharged to the surface by catastraphic floods. Note that the problem of local infiltration is not significantly improved even if the cryosphere were initially dry, for as water attempts to infiltrate the cold, dry crust, it will quickly freeze, creating a seal that prevents any further infiltration from the ponded water above

  15. Development, reproductive capacity and survival of Amblyomma variegatum and Boophilus decoloratus in relation to host resistance and climatic factors under field conditions

    National Research Council Canada - National Science Library

    Solomon, G; Kaaya, G.P

    1998-01-01

    To determine the developmental periods, fecundity and survival of Amblyomma variegatum and Boophilus decoloratus and the effect of host resistance, a study was carried out in the field at Abernossa...

  16. Influence of aerobic and anaerobic conditions on survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in Luria-Bertani broth, farm-yard manure and slurry

    NARCIS (Netherlands)

    Semenov, A.V.; Overbeek, van L.S.; Termorshuizen, A.J.; Bruggen, van A.H.C.

    2011-01-01

    The influence of aerobic and anaerobic conditions on the survival of the enteropathogens Escherichia coli O157:H7 and Salmonella serovar Typhimurium was investigated in microcosms with broth, cattle manure or slurry. These substrates were inoculated with a green fluorescent protein transformed

  17. Influence of aerobic and anaerobic conditions on survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in Luria-Bertani broth, farm-yard manure and slurry

    NARCIS (Netherlands)

    Semenov, Alexander V.; van Overbeek, Leo; Termorshuizen, Aad J.; van Bruggen, Ariena H. C.

    The influence of aerobic and anaerobic conditions on the survival of the enteropathogens Escherichia coli O157:H7 and Salmonella serovar Typhimurium was investigated in microcosms with broth, cattle manure or slurry. These substrates were inoculated with a green fluorescent protein transformed

  18. Alteration of Sedimentary Clasts in Martian Meteorite Northwest Africa 7034

    Science.gov (United States)

    McCubbin, F. M.; Tartese, R.; Santos, A. R.; Domokos, G.; Muttik, N.; Szabo, T.; Vazquez, J.; Boyce, J. W.; Keller, L. P.; Jerolmack, D. J.; hide

    2014-01-01

    The martian meteorite Northwest Africa (NWA) 7034 and pairings represent the first brecciated hand sample available for study from the martian surface [1]. Detailed investigations of NWA 7034 have revealed substantial lithologic diversity among the clasts [2-3], making NWA 7034 a polymict breccia. NWA 7034 consists of igneous clasts, impact-melt clasts, and "sedimentary" clasts represented by prior generations of brecciated material. In the present study we conduct a detailed textural and geochemical analysis of the sedimentary clasts.

  19. Multinationals and plant survival

    DEFF Research Database (Denmark)

    Bandick, Roger

    2010-01-01

    The aim of this paper is twofold: first, to investigate how different ownership structures affect plant survival, and second, to analyze how the presence of foreign multinational enterprises (MNEs) affects domestic plants’ survival. Using a unique and detailed data set on the Swedish manufacturing...... sector, I am able to separate plants into those owned by foreign MNEs, domestic MNEs, exporting non-MNEs, and purely domestic firms. In line with previous findings, the result, when conditioned on other factors affecting survival, shows that foreign MNE plants have lower survival rates than non......-MNE plants. However, separating the non-MNEs into exporters and non-exporters, the result shows that foreign MNE plants have higher survival rates than non-exporting non-MNEs, while the survival rates of foreign MNE plants and exporting non-MNE plants do not seem to differ. Moreover, the simple non...

  20. Refining Martian Ages and Understanding Geological Processes From Cratering Statistics

    Science.gov (United States)

    Hartmann, William K.

    2005-01-01

    Senior Scientist William K. Hartman presents his final report on Mars Data Analysis Program grant number NAG5-12217: The third year of the three-year program was recently completed in mid-2005. The program has been extremely productive in research and data analysis regarding Mars, especially using Mars Global Surveyor and Mars Odyssey imagery. In the 2005 alone, three papers have already been published, to which this work contributed.1) Hartmann, W. K. 200.5. Martian cratering 8. Isochron refinement and the history of Martian geologic activity Icarus 174, 294-320. This paper is a summary of my entire program of establishing Martian chronology through counts of Martian impact craters. 2) Arfstrom, John, and W. K. Hartmann 2005. Martian flow features, moraine-like rieges, and gullies: Terrestrial analogs and interrelationships. Icarus 174,32 1-335. This paper makes pioneering connections between Martian glacier-like features and terrestrial glacial features. 3) Hartmann, W.K., D. Winterhalter, and J. Geiss. 2005 Chronology and Physical Evolution of Planet Mars. In The Solar System and Beyond: Ten Years of ISSI (Bern: International Space Science Institute). This is a summary of work conducted at the International Space Science Institute with an international team, emphasizing our publication of a conference volume about Mars, edited by Hartmann and published in 2001.

  1. Relevance of Pitted Material and Impact Melt to Early Martian Hydrothermalism and Habitability; Ries Ejecta Deposits as a Martian Analogue

    Science.gov (United States)

    Caudill, C. M.; Greenberger, R. N.; Tornabene, L. L.; Osinski, G. R.; Flemming, R. L.; Ehlmann, B. L.

    2017-10-01

    Hydrothermal features are investigated at the Ries impact structure as potentially analogous to crater-related pitted material in Martian ancient terrains, which may reveal shallow sub-surface hydrothermal environments and prime exploration targets.

  2. Origin and Reactivity of the Martian Soil: A 2003 Micromission

    Science.gov (United States)

    Yen, Albert S.; Kim, S. Sam; Marshall, John; Murray, Bruce C.

    1999-01-01

    The role of water in the development of the martian surface remains a fundamental scientific question. Did Mars have one or more "warm and wet" climatic episodes where liquid water was stable at the surface? If so, the mineral phases present in the soils should be consistent with a history of aqueous weathering. More generally, the formation of hydrated mineral phases on Mars is a strong indicator of past habitable surface environments. The primary purpose of this investigation is to help resolve the question of whether such aqueous indicators are present on Mars by probing the upper meter for diagnostic mineral species. According to Burns [1993], the formation of the ferric oxides responsible for the visible color of Mars are the result of dissolution of Fe (+2) phases from basalts followed by aqueous oxidation and precipitation of Fe" mineral assemblages. These precipitates likely included iron oxyhydroxides such as goethite (a-FeOOH) and lepidocrocite (g-FeOOH), but convincing evidence for these phases at the surface is still absent. The stability of these minerals is enhanced beneath the surface, and thus we propose a subsurface search for hydroxylated iron species as a test for a large-scale chemical weathering process based on interactions with liquid water. It is also possible that the ferric minerals on Mars are not aqueous alteration products of the rocks. A chemical study of the Pathfinder landing site concluded that the soils are not directly derived from the surrounding rocks and are enhanced in Mg and Fe. The additional source of these elements might be from other regions of Mars and transported by winds, or alternatively, from exogenic sources. Gibson [1970] proposed that the spectral reflectivity of Mars is consistent with oxidized meteoritic material. Yen and Murray [1998] further extend Gibson's idea and show, in the laboratory, that metallic iron can be readily oxidized to maghemite and hematite under present-day martian surface conditions (in the

  3. New shock-induced transformations of olivines in Martian meteorites

    Science.gov (United States)

    Reynard, B.; van de Moortele, B.; Beck, P.; Gillet, P.; McMillan, P. F.

    2006-12-01

    Transient high pressures and temperatures generated during the impact of meteors or asteroids on planetary surfaces can induce phase transformations in low-pressure minerals that mimic those occurring at depth within the silicate mantle of terrestrial planets. For olivine, phase transitions to the high-pressure polymorphs wadsleyite and ringwoodite are observed in shocked chondrites. Melting transitions have also been reported in some samples. We have investigated the transformations of the olivine presenting an unusually black color in two newly-described Martian meteorites NWA2737 and NWA1950. The shock conditions were not sufficient to cause melting or transformation into the high-pressure polymorphs. The black color of the olivines is due to the presence of Fe-Ni metallic nanoparticles that result from loss of oxygen during the shock event. Raman spectroscopy and high-resolution transmission electron microscopy indicate that the shocked "olivines" have a hexagonal close-packed (hcp) structure similar to that observed in the metastable transformations of olivine at high pressure and low temperature, and of wadsleyite at low pressure and moderate temperatures. We propose a metastable phase diagram of olivine including a new hcp phase that accounts for the observations in natural samples and the experimental results.

  4. Decomposition of sodium formate and L- and D-alanine in the Pampas de La Joya soils: Implications as a new geochemical analogue to Martian regolith

    Science.gov (United States)

    Valdivia-Silva, Julio E.; Navarro-González, Rafael; de la Rosa, José McKay, Christopher P.

    2012-03-01

    The organic compounds on the Martian surface are still undetectable by the previous Viking mission that has been sent to Mars even though they are expected to be there by exogenous and/or endogenous synthesis. The high abiotic reactivity has been the most acceptable explanation for the apparently absence of organic matter in the regolith.Earth soils that have geochemical properties similar to those expected on the surface of Mars could help to decipher this question on the surface and shallow subsurface of the Red Planet. This work aims to demonstrate that the place known as the Pampas de La Joya desert in southern Peru, contains soils that have nonbiological chemical decomposition mechanisms of organic compounds under conditions of the Viking Labeled Release Experiment (LRx). We compare the organic decomposition kinetics of these hyper-arid soils with those seen in samples from arid and semiarid regions of the Atacama Desert, and data obtained by Viking LRx in the Martian regolith. 13Carbon-labeled organic compounds (sodium formate, D-, and L-alanine) were added in aqueous solution to different soil samples in order to analyze the evolved carbon dioxide (13CO2) generated during their degradation. As expected, there were significant differences in the evolved gas behavior between soil samples under similar experimental conditions. When sodium formate was added to hyper-arid samples, there was a peak of 13CO2 gas released demonstrating high oxidation activity in the soil. Heat treatment of soil samples did not completely eliminate the CO2 production. An increase in the decomposition rates ˜7 days after the first addition of organics showed a response consistent with biological activity. The addition of D- and L-alanine demonstrated that the production of 13CO2 due to biological decomposition began 5-8 days after incubation. Our results suggest that these soils from Pampas de La Joya present at least two types of oxidants, a thermostable one which is highly

  5. Shock experiments in support of the Lithopanspermia theory: The influence of host rock composition, temperature, and shock pressure on the survival rate of endolithic and epilithic microorganisms

    Science.gov (United States)

    Meyer, Cornelia; Fritz, Jörg; Misgaiski, Martin; Stäffler, Dieter; Artemieva, Natalia A.; Hornemann, Ulrich; Moeller, Ralf; de Vera, Jean-Pierre; Cockell, Charles; Horneck, Gerda; Ott, Sieglinde; Rabbow, Elke

    2011-05-01

    Shock recovery experiments were performed with an explosive set-up in which three types of microorganisms embedded in various types of host rocks were exposed to strong shock waves with pressure pulse lengths of lower than 0.5 μs: spores of the bacterium Bacillus subtilis, Xanthoria elegans lichens, and cells of the cyanobacterium Chroococcidiopsis sp. 029. In these experiments, three fundamental parameters were systematically varied (1) shock pressures ranging from 5 to 50 GPa, (2) preshock ambient temperature of 293, 233 and 193 K, and (3) the type of host rock, including nonporous igneous rocks (gabbro and dunite as analogs for the Martian shergottites and chassignites, respectively), porous sandstone, rock salt (halite), and a clay-rich mineral mixture as porous analogs for dry and water-saturated Martian regolith. The results show that the three parameters have a strong influence on the survival rates of the microorganisms. The most favorable conditions for the impact ejection from Mars for microorganisms would be (1) low porosity host rocks, (2) pressures <10-20 GPa, and (3) low ambient temperature of target rocks during impact. All tested microorganisms were capable of surviving to a certain extent impact ejection in different geological materials under distinct conditions.

  6. Electrostatic Precipitation of Dust in the Martian Atmosphere: Implications for the Utilization of Resources During Future Manned Exploration Missions

    Science.gov (United States)

    Calle, Carlos I.; Clements, Judson S.; Thompson, Samuel M.; Cox, Nathan D.; Hogue, Michael D.; Johansen, Michael R.; Williams, Blakeley S.

    2011-01-01

    Future human missions to Mars will require the utilization of local resources for oxygen, fuel. and water. The In Situ Resource Utilization (ISRU) project is an active research endeavor at NASA to develop technologies that can enable cost effective ways to live off the land. The extraction of oxygen from the Martian atmosphere. composed primarily of carbon dioxide, is one of the most important goals of the Mars ISRU project. The main obstacle is the relatively large amount of dust present in the Martian atmosphere. This dust must be efficiently removed from atmospheric gas intakes for ISRU processing chambers. A common technique to achieve this removal on earth is by electrostatic precipitation, where large electrostatic fields are established in a localized region to precipitate and collect previously charged dust particles. This technique is difficult to adapt to the Martian environment, with an atmospheric pressure of about one-hundredth of the terrestrial atmosphere. At these low pressures. the corona discharges required to implant an electrostatic charge to the particles to be collected is extremely difficult to sustain and the corona easily becomes biopolar. which is unsuitable for particle charging. In this paper, we report on our successful efforts to establish a stable corona under Martian simulated conditions. We also present results on dust collecting efficiencies with an electrostatic precipitator prototype that could be effectively used on a future mission to the red planet

  7. Electrostatic precipitation of dust in the Martian atmosphere: Implications for the utilization of resources during future manned exploration missions

    Science.gov (United States)

    Calle, C. I.; Thompson, S. M.; Cox, N. D.; Johansen, M. R.; Williams, B. S.; Hogue, M. D.; Clements, J. S.

    2011-12-01

    Future human missions to Mars will require the utilization of local resources for oxygen, fuel, and water. The In Situ Resource Utilization (ISRU) project is an active research endeavor at NASA to develop technologies that can enable cost effective ways to live off the land. The extraction of oxygen from the Martian atmosphere, composed primarily of carbon dioxide, is one of the most important goals of the Mars ISRU project. The main obstacle is the relatively large amount of dust present in the Martian atmosphere. This dust must be efficiently removed from atmospheric gas intakes for ISRU processing chambers. A common technique to achieve this removal on earth is by electrostatic precipitation, where large electrostatic fields are established in a localized region to charge, precipitate and collect dust particles. This technique is difficult to adapt to the Martian environment, with an atmospheric pressure of about one-hundredth of the terrestrial atmosphere. At these low pressures, the corona discharges required to implant an electrostatic charge to the particles to be collected is extremely difficult to sustain and the corona easily transitions to a glow/streamer discharge, which is unsuitable for particle charging. In this paper, we report on our successful efforts to establish a stable corona under Martian simulated conditions. We also present results on dust collecting efficiencies with an electrostatic precipitator prototype that could be effectively used on a future mission to the red planet.

  8. Electric Field Generation in Martian Dust Devils

    Science.gov (United States)

    Barth, Erika L.; Farrell, William M.; Rafkin, Scot C. R.

    2015-01-01

    Terrestrial dust devils are known to generate electric fields from the vertical separation of charged dust particles. The particles present within the dust devils on Mars may also be subject to similar charging processes and so likely contribute to electric field generation there as well. However, to date, no Marsin situ instrumentation has been deployed to measure electric field strength. In order to explore the electric environment of dust devils on Mars, the triboelectric dust charging physics from the MacroscopicTriboelectric Simulation (MTS) code has been coupled to the Mars Regional Atmospheric ModelingSystem (MRAMS). Using this model, we examine how macroscopic electric fields are generated within martian dust disturbances and attempt to quantify the time evolution of the electrodynamical system.Electric fields peak for several minutes within the dust devil simulations. The magnitude of the electric field is a strong function of the size of the particles present, the average charge on the particles and the number of particles lifted. Varying these parameters results in peak electric fields between tens of millivolts per meter and tens of kilovolts per meter.

  9. High-Capacity Communications from Martian Distances

    Science.gov (United States)

    Williams, W. Dan; Collins, Michael; Hodges, Richard; Orr, Richard S.; Sands, O. Scott; Schuchman, Leonard; Vyas, Hemali

    2007-01-01

    High capacity communications from Martian distances, required for the envisioned human exploration and desirable for data-intensive science missions, is challenging. NASA s Deep Space Network currently requires large antennas to close RF telemetry links operating at kilobit-per-second data rates. To accommodate higher rate communications, NASA is considering means to achieve greater effective aperture at its ground stations. This report, focusing on the return link from Mars to Earth, demonstrates that without excessive research and development expenditure, operational Mars-to-Earth RF communications systems can achieve data rates up to 1 Gbps by 2020 using technology that today is at technology readiness level (TRL) 4-5. Advanced technology to achieve the needed increase in spacecraft power and transmit aperture is feasible at an only moderate increase in spacecraft mass and technology risk. In addition, both power-efficient, near-capacity coding and modulation and greater aperture from the DSN array will be required. In accord with these results and conclusions, investment in the following technologies is recommended:(1) lightweight (1 kg/sq m density) spacecraft antenna systems; (2) a Ka-band receive ground array consisting of relatively small (10-15 m) antennas; (3) coding and modulation technology that reduces spacecraft power by at least 3 dB; and (4) efficient generation of kilowatt-level spacecraft RF power.

  10. The new Martians a scientific novel

    CERN Document Server

    Kanas, Nick

    2014-01-01

    The year is 2035, and the crew from the first expedition to Mars is returning to Earth. The crewmembers are anxious to get home, and ennui pervades the ship. The mood is broken by a series of mysterious events that jeopardize their safety. Someone or something is threatening the crew. Is it an alien being? A psychotic crewmember? A malfunctioning computer? The truth raises questions about the crewmembers’ fate and that of the human race. In this novel, the intent is to show real psychological issues that could affect a crew returning from a long-duration mission to Mars. The storyline presents a mystery that keeps the reader guessing, yet the issues at stake are based on the findings from the author’s research and other space-related work over the past 40+ years. The novel touches on actual plans being discussed for such an expedition as well as notions involving the search for Martian life and panspermia. The underlying science, in particular the psychological, psychiatric, and interpersonal elements...

  11. Ion Heating in the Martian Ionosphere

    Science.gov (United States)

    Fowler, C. M.; Ergun, R. E.; Andersson, L.; Peterson, W. K.; Hara, T.; Mcfadden, J.; Espley, J.; Halekas, J.; Mitchell, D. L.; Mazelle, C.; Jakosky, B. M.

    2017-10-01

    Energetic O+ and O2+ ions with energies of up to a few hundred eV are observed in the Martian ionosphere. Corresponding ion velocity distributions show ion conics, suggesting that the observed ion populations have been heated perpendicular to the local magnetic field before experiencing a magnetic mirror force. Magnetic field observations support these interpretations: wave power at the local O+ and O2+ gyrofrequencies in the spacecraft frame is observed coincident with the energetic ions, within an apparent magnetic field bottle-like topology. Analysis of the observed ion conics leads to estimates of ion temperatures of 10-30 eV. We suggest that the ion populations are initially heated perpendicular to the local magnetic field by wave power propagating inward from the Mars-solar wind interaction. The local magnetic field "balloons out" in response to these enhanced ion temperatures and pressures. The resultant magnetic field topology is bottle like; the transversely heated ions would subsequently experience a magnetic mirror force in the converging field regions, agreeing with the reported observations. Such strong heating events that significantly increase the ion temperature and pressure, thereby decreasing the net magnetic field, are rare and seem to occur under specific interplanetary magnetic field orientations. Events were observed to span the upper exobase region and just above, a region characterized by significant ion densities in an increasingly collisionless domain. Ion heating in this region has the potential to drive significant ion outflows, thus contributing to atmospheric loss from the planet.

  12. The Martian surface radiation environment – a comparison of models and MSL/RAD measurements

    Directory of Open Access Journals (Sweden)

    Matthiä Daniel

    2016-01-01

    Full Text Available Context: The Radiation Assessment Detector (RAD on the Mars Science Laboratory (MSL has been measuring the radiation environment on the surface of Mars since August 6th 2012. MSL-RAD is the first instrument to provide detailed information about charged and neutral particle spectra and dose rates on the Martian surface, and one of the primary objectives of the RAD investigation is to help improve and validate current radiation transport models. Aims: Applying different numerical transport models with boundary conditions derived from the MSL-RAD environment the goal of this work was to both provide predictions for the particle spectra and the radiation exposure on the Martian surface complementing the RAD sensitive range and, at the same time, validate the results with the experimental data, where applicable. Such validated models can be used to predict dose rates for future manned missions as well as for performing shield optimization studies. Methods: Several particle transport models (GEANT4, PHITS, HZETRN/OLTARIS were used to predict the particle flux and the corresponding radiation environment caused by galactic cosmic radiation on Mars. From the calculated particle spectra the dose rates on the surface are estimated. Results: Calculations of particle spectra and dose rates induced by galactic cosmic radiation on the Martian surface are presented. Although good agreement is found in many cases for the different transport codes, GEANT4, PHITS, and HZETRN/OLTARIS, some models still show large, sometimes order of magnitude discrepancies in certain particle spectra. We have found that RAD data is helping to make better choices of input parameters and physical models. Elements of these validated models can be applied to more detailed studies on how the radiation environment is influenced by solar modulation, Martian atmosphere and soil, and changes due to the Martian seasonal pressure cycle. By extending the range of the calculated particle

  13. No effect of satellite tagging on survival, recruitment, longevity, productivity and social dominance of a raptor, and the provisioning and condition of its offspring

    National Research Council Canada - National Science Library

    Sergio, Fabrizio; Tavecchia, Giacomo; Tanferna, Alessandro; López Jiménez, Lidia; Blas, Julio; De Stephanis, Renaud; Marchant, Tracy A; Kumar, Nishant; Hiraldo, Fernando; Wilson, Jeremy

    2015-01-01

    ... . ). In turn, this facilitates estimates of migratory performance, survival rates and causes of mortality only dreamt of until very recently, as the biases generated by poor sampling of unpopulated, remote or inaccessible areas are virtually removed (e.g. Croxall et al . ; Burnham & Newton ; Klaassen et al . ). However, several recent studies have shown ...

  14. Cryolitozone of Mars- as the climatic indicator of the Martian relict ocean

    Science.gov (United States)

    Ozorovich, Y.; Fournier-Sicre, A.; Linkin, V.; Kosov, A.; Skulachev, D.; Gorbatov, S.; Ivanov, A.; Heggy, E.

    2015-10-01

    The existance of a large Martian cryolitozone consisting of different cryogenic formations both on the surface- polar caps ice and in subsurface layer (and probably overcooled salt solutions in lower horizons) is conditioned mostly by the planet's geological history and atmosphere evolution. The very structure of the cryolitozone with its strongly pronounced zone character owing to drying up of 0 to 200 m thick surface layer in the equatorial latitudes ranging from + 30 to - 300 was formed in the course of long-periodic climatic variations and at present is distincly heterogeneous both depthward and in latitudinal and longtudinal dimensions. The dryed up region of Martian frozen rocks is estimated to have been developing during more than 3.5 bln years, so the upper layer boundary of permafrost can serve as a sort of indicator reflecting the course of Martian climatic evolution. Since the emount of surface moisture and its distribition character are conditioned by the cryolitozone scale structure its investigation is considered to be an important aspect of the forthcoming Martian projects. In order to create Martian climate and atmosphere circulation models the whole complex information on surface provided by optical and infrared ranges observations, regional albedo surface measurements, ground layer thermal flow investigations, etc. must be carefully studed. The investigation of permafrost formation global distribution and their appearance in h ≤1 m thick subsurface layer may be provided successfully by using active-passive microwave remote sensing techniques [1]. Along with optical and infrared observations the method of orbital panoramic microwave radiometry in centi- and decimeter ranges would contribute to the mapping of the cryolitozone global surface distribution. This proposal discusses methodical and experimental possibilities of this global observation of Martian cryolitozone as the additional way for investigation subsurface of Mars. The main idea of

  15. Silver contents and Cu/Ag ratios in Martian meteorites and the implications for planetary differentiation

    Science.gov (United States)

    Wang, Zaicong; Becker, Harry

    2017-11-01

    Silver and Cu show very similar partitioning behavior in sulfide melt-silicate melt and metal-silicate systems at low and high pressure-temperature (P-T) experimental conditions, implying that mantle melting, fractional crystallization and core-mantle differentiation have at most modest (within a factor of 3) effects on Cu/Ag ratios. For this reason, it is likely that Cu/Ag ratios in mantle-derived magmatic products of planetary bodies reflect that of the mantle and, in some circumstances, also the bulk planet composition. To test this hypothesis, new Ag mass fractions and Cu/Ag ratios in different groups of Martian meteorites are presented and compared with data from chondrites and samples from the Earth's mantle. Silver contents in lherzolitic, olivine-phyric and basaltic shergottites and nakhlites range between 1.9 and 12.3 ng/g. The data display a negative trend with MgO content and correlate positively with Cu contents. In spite of displaying variable initial Ɛ143Nd values and representing a diverse spectrum of magmatic evolution and physiochemical conditions, shergottites and nakhlites display limited variations of Cu/Ag ratios (1080 ± 320, 1 s, n = 14). The relatively constant Cu/Ag suggests limited fractionation of Ag from Cu during the formation and evolution of the parent magmas, irrespectively of whether sulfide saturation was attained or not. The mean Cu/Ag ratio of Martian meteorites thus reflects that of the Martian mantle and constrains its Ag content to 1.9 ± 0.7 ng/g (1 s). Carbonaceous and enstatite chondrites display a limited range of Cu/Ag ratios of mostly 500-2400. Ordinary chondrites show a larger scatter of Cu/Ag up to 4500, which may have been caused by Ag redistribution during parent body metamorphism. The majority of chondrites have Cu/Ag ratios indistinguishable from the Martian mantle value, indicating that Martian core formation strongly depleted Cu and Ag contents, but probably did not significantly change the Cu/Ag ratio of the

  16. Martian mud volcanism: Terrestrial analogs and implications for formational scenarios

    Science.gov (United States)

    Skinner, J.A.; Mazzini, A.

    2009-01-01

    The geology of Mars and the stratigraphic characteristics of its uppermost crust (mega-regolith) suggest that some of the pervasively-occurring pitted cones, mounds, and flows may have formed through processes akin to terrestrial mud volcanism. A comparison of terrestrial mud volcanism suggests that equivalent Martian processes likely required discrete sedimentary depocenters, volatile-enriched strata, buried rheological instabilities, and a mechanism of destabilization to initiate subsurface flow. We outline five formational scenarios whereby Martian mud volcanism might have occurred: (A) rapid deposition of sediments, (B) volcano-induced destabilization, (C) tectonic shortening, (D) long-term, load-induced subsidence, and (E) seismic shaking. We describe locations within and around the Martian northern plains that broadly fit the geological context of these scenarios and which contain mud volcano-like landforms. We compare terrestrial and Martian satellite images and examine the geological settings of mud volcano provinces on Earth in order to describe potential target areas for piercement structures on Mars. Our comparisons help to evaluate not only the role of water as a functional component of geological processes on Mars but also how Martian mud volcanoes could provide samples of otherwise inaccessible strata, some of which could contain astrobiological evidence.

  17. Water in Pyroxene and Olivine from Martian Meteorites

    Science.gov (United States)

    Peslier, A. H.

    2012-01-01

    Water in the interior of terrestrial planets can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) like olivine, pyroxene, or feldspar [1-3]. Although these minerals contain only tens to hundreds of ppm H2O, this water can amount to at least one ocean in mass when added at planetary scales because of the modal dominance of NAM in the mantle and crust [4]. Moreover these trace amounts of water can have drastic effects on melting temperature, rheology, electrical and heat conductivity, and seismic wave attenuation [5]. There is presently a debate on how much water is present in the martian mantle. Secondary ionization mass spectrometry (SIMS) studies of NAM [6], amphiboles and glass in melt inclusions [7-10], and apatites [11, 12] from Martian meteorites report finding as much water as in the same phases from Earth's igneous rocks. Most martian hydrous minerals, however, generally have the relevant sites filled with Cl and F instead of H [13, 14], and experiments using Cl [15] in parent melts can reproduce Martian basalt compositions as well as those with water [16]. We are in the process of analyzing Martian meteorite minerals by Fourier transform infrared spectrometry (FTIR) in order to constrain the role of water in this planet s formation and magmatic evolution

  18. LU-HF Age of Martian Meteorite Larkman Nunatek 06319

    Science.gov (United States)

    Shafer, J. T.; Brandon, A. D.; Lapen, T. J.; Righter, M.; Beard, B.; Peslier, A. H.

    2009-01-01

    Lu-Hf isotopic data were collected on mineral separates and bulk rock powders of LAR 06319, yielding an age of 197+/- 29 Ma. Sm-Nd isotopic data and in-situ LA-ICP-MS data from a thin section of LAR 06319 are currently being collected and will be presented at the 2009 LPSC. These new data for LAR 06319 extend the existing data set for the enriched shergottite group. Martian meteorites represent the only opportunity for ground truth investigation of the geochemistry of Mars [1]. At present, approximately 80 meteorites have been classified as Martian based on young ages and distinctive isotopic signatures [2]. LAR 06319 is a newly discovered (as part of the 2006 ANSMET field season) martian meteorite that represents an important opportunity to further our understanding of the geochemical and petrological constraints on the origin of Martian magmas. Martian meteorites are traditionally categorized into the shergottite, nakhlite, and chassignite groups. The shergottites are further classified into three distinct isotopic groups designated depleted, intermediate, and enriched [3,4] based on the isotope systematics and compositions of their source(s).

  19. Structural Origins of Martian Pit Chains

    Science.gov (United States)

    Wyrick, D.; Ferrill, D. A.; Morris, A. P.; Colton, S. L.; Sims, D. W.

    2003-12-01

    Pit craters are circular to elliptical depressions found in alignments (chains), which in many cases coalesce into linear troughs, and are common on the surface of Mars. Pit craters lack an elevated rim, ejecta deposits, or lava flows that are associated with impact craters or calderas. It is generally agreed that these features are formed by collapse into a subsurface cavity. Hypotheses regarding the formation of pit crater chains require development of a substantial subsurface void to accommodate collapse of the overlying sediments. Suggested mechanisms of formation include: collapsed lava tubes, dike swarms, collapsed magma chamber, karst dissolution, fissuring beneath loose material, and dilational faulting. The research described here is intended to constrain current interpretations of pit crater chain formation by analyzing their distribution and morphology. The western hemisphere of Mars was systematically mapped using Mars Orbiter Camera (MOC) images to generate ArcView Geographic Information System (GIS) coverages. All visible pit crater chains were mapped, including their orientations and associations with other structures. We found that pit chains commonly occur in areas that show regional extension or local fissuring. There is a strong correlation between pit chains and fault-bounded grabens. Frequently, there are transitions along strike from (i) visible faulting to (ii) faults and pits to (iii) pits alone. We performed a detailed quantitative analysis of pit crater morphology using MOC narrow angle images, Thermal Emission Imaging System (THEMIS) visual images and Mars Orbiter Laser Altimeter (MOLA) data. This allowed us to interpret a pattern of pit chain evolution and calculate pit depth, slope, and volume. The information collected in the study was then compared with non-Martian examples of pit chains and physical analog models. We evaluated the various mechanisms for pit chain development based on the data collected and conclude that dilational

  20. Feeding ω-3 PUFA enriched rotifers to Galaxias maculatus (Jenyns, 1842 larvae reared at different salinity conditions: effects on growth parameters, survival and fatty acids profile

    Directory of Open Access Journals (Sweden)

    Patricio Dantagnan

    2013-07-01

    Full Text Available Despite the well known importance of ω-3 polyunsaturated fatty acids (PUFA in marine and freshwater fish larvae, there are few studies on how essential fatty acid requirements and composition on whole body can be altered by changes in water salinity. The present study aimed to determine the effect of salinity on ω-3 PUFA requirements, larval growth survival and fatty acid composition of Galaxias maculatus larvae cultured at two different salinities (0 and 15 g L-1 for 20 days while fed rotifers containing two different levels of ω-3 PUFA (1.87 and 3.16%. The results denoted a marked difference in ω-3 PUFA requirements and in the pattern of fatty acid deposition in the whole body of larvae reared at different salinities, depending of ω-3 PUFA in diets. Thus, to improve growth and survival larvae of G. maculatus reared at 0 g L-1 require higher levels of ω-3 PUFA, principally 18:3 ω-3. Larvae reared at salinities of 15 g L-1 require low levels of ω-3 PUFA for optimal survival, especially 18:3 ω-3. Eicosapentaenoic acid and docosahexaenoic acid content in the whole body of larvae was also affected by water salinity.

  1. Next Steps Forward in Understanding Martian Surface and Subsurface Chemistry

    Science.gov (United States)

    Carrier, Brandi L.

    2017-09-01

    The presence of oxidants such as hydrogen peroxide (H2O2) and perchlorate (ClO4-), which have been detected on Mars, has significant implications for chemistry and astrobiology. These oxidants can increase the reactivity of the Martian soil, accelerate the decomposition of organic molecules, and depress the freezing point of water. The study by Crandall et al. "Can Perchlorates be Transformed to Hydrogen Peroxide Products by Cosmic Rays on the Martian Surface" reveals a new formation mechanism by which hydrogen peroxide and other potential oxidants can be generated via irradiation of perchlorate by cosmic rays. This study represents an important next step in developing a full understanding of Martian surface and subsurface chemistry, particularly with respect to degradation of organic molecules and potential biosignatures.

  2. Iron Redox Systematics of Shergottites and Martian Magmas

    Science.gov (United States)

    Righter, Kevin; Danielson, L. R.; Martin, A. M.; Newville, M.; Choi, Y.

    2010-01-01

    Martian meteorites record a range of oxygen fugacities from near the IW buffer to above FMQ buffer [1]. In terrestrial magmas, Fe(3+)/ SigmaFe for this fO2 range are between 0 and 0.25 [2]. Such variation will affect the stability of oxides, pyroxenes, and how the melt equilibrates with volatile species. An understanding of the variation of Fe(3+)/SigmaFe for martian magmas is lacking, and previous work has been on FeO-poor and Al2O3-rich terrestrial basalts. We have initiated a study of the iron redox systematics of martian magmas to better understand FeO and Fe2O3 stability, the stability of magnetite, and the low Ca/high Ca pyroxene [3] ratios observed at the surface.

  3. Solar wind interaction with the Martian upper atmosphere: Crustal field orientation, solar cycle, and seasonal variations

    Science.gov (United States)

    Dong, Chuanfei; Bougher, Stephen W.; Ma, Yingjuan; Toth, Gabor; Lee, Yuni; Nagy, Andrew F.; Tenishev, Valeriy; Pawlowski, Dave J.; Combi, Michael R.; Najib, Dalal

    2015-09-01

    A comprehensive study of the solar wind interaction with the Martian upper atmosphere is presented. Three global models: the 3-D Mars multifluid Block Adaptive Tree Solar-wind Roe Upwind Scheme MHD code (MF-MHD), the 3-D Mars Global Ionosphere Thermosphere Model (M-GITM), and the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS) were used in this study. These models are one-way coupled; i.e., the MF-MHD model uses the 3-D neutral inputs from M-GITM and the 3-D hot oxygen corona distribution from M-AMPS. By adopting this one-way coupling approach, the Martian upper atmosphere ion escape rates are investigated in detail with the combined variations of crustal field orientation, solar cycle, and Martian seasonal conditions. The calculated ion escape rates are compared with Mars Express observational data and show reasonable agreement. The variations in solar cycles and seasons can affect the ion loss by a factor of ˜3.3 and ˜1.3, respectively. The crustal magnetic field has a shielding effect to protect Mars from solar wind interaction, and this effect is the strongest for perihelion conditions, with the crustal field facing the Sun. Furthermore, the fraction of cold escaping heavy ionospheric molecular ions [(O2+ and/or O2+)/Total] are inversely proportional to the fraction of the escaping (ionospheric and corona) atomic ion [O+/Total], whereas O2+ and O2+ ion escape fractions show a positive linear correlation since both ion species are ionospheric ions that follow the same escaping path.

  4. Earth analogs for Martian life - Microbes in evaporites, a new model system for life on Mars

    Science.gov (United States)

    Rothschild, Lynn J.

    1990-01-01

    It is suggested that 'oases' in which life forms may persist on Mars could occur, by analogy with terrestrial cases, in (1) rocks, as known in endolithic microorganisms, (2) polar ice caps, as seen in snow and ice algae, and (3) volcanic regions, as witnessed in the chemoautotrophs which live in ocean-floor hydrothermal vents. Microorganisms, moreover, have been known to survive in salt crystals, and it has even been shown that organisms can metabolize while encrusted in evaporites. Evaporites which may occur on Mars would be able to attenuate UV light, while remaining more transparent to the 400-700 nm radiation useful in photosynthesis. Suggestions are made for the selection of Martian exobiological investigation sites.

  5. MARTIAN SWARM EXPLORATION AND MAPPING USING LASER SLAM

    Directory of Open Access Journals (Sweden)

    S. Nowak

    2013-08-01

    Full Text Available In order to explore planet Mars in detail and search for extra-terrestrial life the observation from orbit is not sufficient. To realize complex exploration tasks the use of automatic operating robots with a robust fault-tolerant method of navigation, independent of any infrastructure is a possibility. This work includes a concept of rotary-wing Unmanned Aerial Vehicles (UAVs and Unmanned Ground Vehicles (UGVs for Martian exploration in a swarm. Besides the scenario of Martian surrounding, with a small number of distinctive landmarks, the challenge consists of a Simultaneous Localization and Mapping (SLAM concept using laser data of all swarm members.

  6. The Modern Near-Surface Martian Climate: A Review of In-situ Meteorological Data from Viking to Curiosity

    Science.gov (United States)

    Martínez, G. M.; Newman, C. N.; De Vicente-Retortillo, A.; Fischer, E.; Renno, N. O.; Richardson, M. I.; Fairén, A. G.; Genzer, M.; Guzewich, S. D.; Haberle, R. M.; Harri, A.-M.; Kemppinen, O.; Lemmon, M. T.; Smith, M. D.; de la Torre-Juárez, M.; Vasavada, A. R.

    2017-10-01

    We analyze the complete set of in-situ meteorological data obtained from the Viking landers in the 1970s to today's Curiosity rover to review our understanding of the modern near-surface climate of Mars, with focus on the dust, CO2 and H2O cycles and their impact on the radiative and thermodynamic conditions near the surface. In particular, we provide values of the highest confidence possible for atmospheric opacity, atmospheric pressure, near-surface air temperature, ground temperature, near-surface wind speed and direction, and near-surface air relative humidity and water vapor content. Then, we study the diurnal, seasonal and interannual variability of these quantities over a span of more than twenty Martian years. Finally, we propose measurements to improve our understanding of the Martian dust and H2O cycles, and discuss the potential for liquid water formation under Mars' present day conditions and its implications for future Mars missions. Understanding the modern Martian climate is important to determine if Mars could have the conditions to support life and to prepare for future human exploration.

  7. Tracer transport in the Martian atmosphere

    Science.gov (United States)

    Lian, Y.; Richardson, M. I.; Newman, C. E.; Lee, C.; Toigo, A. D.; Campin, J.

    2011-12-01

    Transport is crucial to understanding and reproducing the Martian dust and water cycles, and to interpreting putative methane and other trace gas (e.g. Argon) observations. However, as quantified by comparing model predictions with Argon measurements made by the Gamma Ray Spectrometer [e.g. Sprague et al., 2004, 2007], current Mars general circulation models (GCM's) appear to do a poor job at tracer transport [e.g. Nelli et al., 2007]. This invalidates a core assumption of GCM modeling in the last decade - that transport is sufficiently well treated in models that we need focus only on improving physical parameterizations, and that differences between results from different GCM's stem purely from their treatment of physical processes. If instead it is the simulated dynamical processes that need better treatment we need to move towards higher-quality numerics, e.g. based on the finite volume formulation, and introduce a more sophisticated approach to advection following work done for terrestrial chemical transport modeling. Here we present the results of non-condensable tracer transport simulations using our newly developed Mars MITgcm, which has both of the aforementioned desirable attributes: a finite volume core and access to a range of sophisticated advection schemes. Our results are encouraging in that we are able to reproduce the observed peak polar Argon enhancement factor of six (about double that attainable with most other Mars GCMs). Our diagnostics show that the time-averaged zonal-mean advection produces net increases of Argon at the winter poles, while stationary and transient eddies transport Argon away from the poles. Using less diffusive nonlinear advection schemes with flux limiters tends to produce more advective fluxes of tracers into the southern winter pole than the more diffusive linear advection schemes, resulting in a greater net increase of polar Argon abundance. We further utilize a more realistic k-distribution radiative transfer model, an

  8. What Lies Below a Martian Ice Cap

    Science.gov (United States)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for larger annotated version This image (top) taken by the Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter reveals the layers of ice, sand and dust that make up the north polar ice cap on Mars. It is the most detailed look to date at the insides of this ice cap. The colored map below the radar picture shows the topography of the corresponding Martian terrain (red and white represent higher ground, and green and yellow lower). The radar image reveals four never-before-seen thick layers of ice and dust separated by layers of nearly pure ice. According to scientists, these thick ice-free layers represent approximately one-million-year-long cycles of climate change on Mars caused by variations in the planet's tilted axis and its eccentric orbit around the sun. Adding up the entire stack of ice gives an estimated age for the north polar ice cap of about 4 million years a finding that agrees with previous theoretical estimates. The ice cap is about 2 kilometers (1.2 miles) thick. The radar picture also shows that the boundary between the ice layers and the surface of Mars underneath is relatively flat (bottom white line on the right). This implies that the surface of Mars is not sagging, or bending, under the weight of the ice cap and this, in turn, suggests that the planet's lithosphere, a combination of the crust and the strong parts of the upper mantle, is thicker than previously thought. A thicker lithosphere on Mars means that temperatures increase more gradually with depth toward the interior. Temperatures warm enough for water to be liquid are therefore deeper than previously thought. Likewise, if liquid water does exist in aquifers below the surface of Mars, and if there are any organisms living in that water, they would have to be located deeper in the planet. The topography data are from Mars Orbiter Laser Altimeter, which was flown on NASA's Mars Global Surveyor mission. NPLD stands

  9. Wright Valley Sediments as Potential Analogs for Martian Surface Processes

    Science.gov (United States)

    Englert, P. A. J.; Bishop, J. L.; Patel, S.; Gibson, E. K.; Koeberl, C.

    2015-12-01

    The Antarctic Dry Valleys (ADV) may provide a unique terrestrial analog for current Martian surface processes. The Wright Valley located in the ADV contains streams, lakes and ponds that host highly saline, sedimentary environments. This project highlights comparisons of formation and salt accumulation processes at the Don Juan Pond (DJP) and Don Quixote Pond (DQP). These are located in the north and south forks of the Wright Valley, which are unique areas where unusual terrestrial processes can be studied. DQP is located in the western part of the north fork about 100 m above mean seawater level. The DQP Valley walls are up to 2500 m high and the brine is seasonally frozen. DJP from the south fork is located ~9 km west of Lake Vanda. The basin floor is 117 m above mean seawater level with activity to the north and south rising above 1000 m. The DJP brine does not freeze and may be a model environment for Ca and Cl weathering and distribution on Mars. Our findings indicate that DJP and DQP have formed in similar climatic and geological environments, but likely experienced different formation conditions. Samples were collected from surface, soil pits and depth profiles during the 1979/1980, the 1990/1991 and the 2005/2006 field seasons. Elemental abundances and mineralogy were evaluated for several sets of sediments. The DJP basin shows low surface abundances of halite and relatively high abundances of sulfates throughout with gypsum or anhydrite dominating at different locations. The DQP area has high surface abundances of halite with gypsum present as the major sulfate. Two models have been proposed to explain these differences: DQP may have formed through a combination of shallow and some deep groundwater influx, while deep groundwater upwelling likely played the dominant role of salt formation at DJP. Our study seeks to understand the formation of DQP and DJP as unique terrestrial processes and as models for Ca, Cl, and S weathering and distribution on Mars.

  10. The effect of alginate and chitosan concentrations on some properties of chitosan-coated alginate beads and survivability of encapsulated Lactobacillus rhamnosus in simulated gastrointestinal conditions and during heat processing.

    Science.gov (United States)

    Abbaszadeh, Sepideh; Gandomi, Hassan; Misaghi, Ali; Bokaei, Saeid; Noori, Negin

    2014-08-01

    In this study, chitosan-coated alginate beads were produced with different concentrations of chitosan and alginate to evaluate the survival of encapsulated Lactobacillus rhamnosus GG during exposure to adverse conditions in gastrointestinal simulated juice and heat processing. The encapsulation yield of different encapsulation treatments was between 25 and 53.2%. Although there was a drastic decrease in pH within 48 h of incubation in MRS medium inoculated with free and encapsulated bacteria, no significant changes (P > 0.05) in bacterial count were observed among different encapsulation treatments. Moreover, the survival rate after gastrointestinal juice exposure of all prepared beads was 10-87 times greater than that of free cells and was significantly enhanced by increasing chitosan and alginate concentrations. The encapsulated bacteria survived significantly (P alginate/10 g L(-1) chitosan-encapsulated L. rhamnosus was reduced by only 2.55 log cycles. Encapsulation effectively protected L. rhamnosus against heat treatment and gastrointestinal conditions, and this effect is important in delivering sufficient numbers of viable probiotic bacteria to the gastrointestinal tract. © 2013 Society of Chemical Industry.

  11. Regional variations in the observed morphology and activity of martian linear gullies

    Science.gov (United States)

    Morales, Kimberly Marie; Diniega, Serina; Austria, Mia; Ochoa, Vincent; HiRISE Science and Instrument Team

    2017-10-01

    The formation mechanism for martian linear gullies has been much debated, because they have been suggested as possible evidence of liquid water on Mars. This class of dune gullies is defined by long (up to 2 km), narrow channels that are relatively uniform in width, and range in sinuosity index. Unlike other gullies on Earth and Mars that end in depositional aprons, linear gullies end in circular depressions referred to as terminal pits. This particular morphological difference, along with the difficulty of identifying a source of water to form these features, has led to several ‘dry’ hypotheses. Recent observations on the morphology, distribution, and present-day activity of linear gullies suggests that they could be formed by subliming blocks of seasonal CO2 ice (“dry ice”) sliding downslope on dune faces. In our study, we aimed to further constrain the possible mechanism(s) responsible for the formation of linear gullies by using HiRISE images to collect morphological data and track seasonal activity within three regions in the southern hemisphere-Hellespontus (~45°S, 40°E), Aonia Terra (~50°S, 290°E), and Jeans (~70°S, 155°E) over the last four Mars years. General similarities in these observations were reflective of the proposed formation process (sliding CO2 blocks) while differences were correlated with regional environmental conditions related to the latitude or general geologic setting. This presentation describes the observed regional differences in linear gully morphology and activity, and investigates how environmental factors such as surface properties and local levels of frost may explain these variations while still supporting the proposed model. Determining the formation mechanism that forms these martian features can improve our understanding of both the climatic and geological processes that shape the Martian surface.

  12. Spherulitic (c-axis) Growth for Terrestrial (Mauna Kea, Hawaii) and Martian Hematite "blueberries"

    Science.gov (United States)

    Golden, D. C.; Ming, D. W.; Morris, R. V.

    2006-01-01

    Hematite concentrations observed by Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor were considered a possible indicator for aqueous processes on Mars. Observations made by Opportunity show that the hematite at Meridiani Planum is present as spherules ( blueberries) and their fragments. The internal structure of the hematite spherules is not discernable at the resolution limit (approx.30 m/pixel) of Opportunity s Microscopic Imager (MI). A terrestrial analog for martian hematite spherules are spherules from hydrothermally altered and sulfate-rich tephra from the summit region of Mauna Kea volcano, Hawaii. The objective of this study is to determine the crystal growth fabric of the Mauna Kea hematite spherules using transmission electron microscopy (TEM) techniques and to relate that crystalline fabric to the observed TES signature of Meridiani Planum "blueberries." TEM analysis of Mauna Kea spherules exhibited a radial growth pattern consisting of "fibrous" hematite with the c-axis of hematite particles aligned along the elongation direction of the hematite fibers. The individual fibers appear to be made of coalesced nano-particles of hematite arranged with their c-axis oriented radially to form a spherical structure. Lattice fringes suggest long-range order across particles and along fibers. According to interpretations of thermal emission spectra for Meridian Planum hematite, the absence of a band at approx. 390/cm implies a geometry where c-face emission dominates. Because the c-face is perpendicular to the c-axis, this is precisely the geometry for the Mauna Kea spherules because the c-axis is aligned parallel to their radial growth direction. Therefore, we conclude as a working hypothesis that the martian spherules also have radial, c-axis growth pattern on a scale that is too small to be detected by the MER MI. Furthermore, by analogy with the Mauna Kea spherules, the martian blueberries could have formed during hydrothermal alteration of

  13. Influence of the solar EUV flux on the Martian plasma environment

    Directory of Open Access Journals (Sweden)

    R. Modolo

    2005-02-01

    Full Text Available The interaction of the solar wind with the Martian atmosphere and ionosphere is investigated by using three-dimensional, global and multi-species hybrid simulations. In the present work we focus on the influence of the solar EUV flux on the Martian plasma environment by comparing simulations done for conditions representative of the extrema of the solar cycle. The dynamics of four ionic species (H+, He++, O+, O2+, originating either from the solar wind or from the planetary plasma, is treated fully kinetically in the simulation model in order to characterize the distribution of each component of the plasma, both at solar maximum and at solar minimum. The solar EUV flux controls the ionization frequencies of the exospheric species, atomic hydrogen and oxygen, as well as the density, the temperature, and thus the extension of the exosphere. Ionization by photons and by electron impacts, and the main charge exchange reactions are self-consistently included in the simulation model. Simulation results are in reasonable agreement with the observations made by Phobos-2 and Mars Global Surveyor (MGS spacecraft: 1 the interaction creates a cavity, void of solar wind ions (H+, He++, which depends weakly upon the phase of the solar cycle, 2 the motional electric field of the solar wind flow creates strong asymmetries in the Martian environment, 3 the spatial distribution of the different components of the planetary plasma depends strongly upon the phase of the solar cycle. The fluxes of the escaping planetary ions are computed from the simulated data and results for solar maximum are compared with estimates based on the measurements made by experiments ASPERA and TAUS on board Phobos-2.

  14. Compositional dependence of sulfur speciation in Terrestrial and Martian magmas

    Science.gov (United States)

    Nash, William; Wood, Bernard; Smythe, Duane

    2016-04-01

    The capacity of magmas to transport sulfur from mantle to crust strongly influences a planet's surface chemistry. Sulfur is perhaps exceptional among the elements in the diversity of it's chemical speciation, exhibiting four redox species at geologically relevant conditions: sulfide (2-), elemental sulfur (0), sulfite (4+) and sulphate (6+). Furthermore, the solubility of sulfur in a magma (and hence the magma's capacity for delivering mantle-derived sulfur to the crust) depends critically on it's oxidation state. Our aim with this experimental study was to quantitatively determine the chemical speciation of sulfur within several common magmas, as a function of oxygen fugacity (fO2). We have performed a series of experiments on six sulfur-bearing silicate melts, which together represent a broad range of naturally occurring compositions: two putative Martian basalts, two terrestrial MORBs (one primitive, one evolved), an andesite, and a dacite. These melts were equilibrated together (at one-atmosphere pressure, 1300°C) with various CO-CO2-SO2 gas mixtures, which imposed a range of fO2s. This range spanned -2 to +1.6 log units (relative to the Quartz-Fayalite-Magnetite or QFM buffer), and the step-size was 0.25 log units. The quenched glasses were analyzed by X-ray Absorption Spectroscopy (specifically XANES) at the Diamond synchrotron (UK), and the spectra obtained were used to determine the species of sulfur present in each glass. The chemical composition of each glass (including their sulfur contents) was characterized by electron-probe microanalysis. Despite the generally low concentrations of sulfur in our glasses (never exceeding 0.24 wt%), we have clearly resolved the crossover between reduced (S2-) and oxidized (S6+) species for three of our basalts. The other three melts yielded more noisy XANES spectra, and as a result their redox crossovers are visible, but less clearly resolved. For every melt composition, the redox crossover is a continuous (though

  15. Local Dynamics of Baroclinic Waves in the Martian Atmosphere

    KAUST Repository

    Kavulich, Michael J.

    2013-11-01

    The paper investigates the processes that drive the spatiotemporal evolution of baroclinic transient waves in the Martian atmosphere by a simulation experiment with the Geophysical Fluid Dynamics Laboratory (GFDL) Mars general circulation model (GCM). The main diagnostic tool of the study is the (local) eddy kinetic energy equation. Results are shown for a prewinter season of the Northern Hemisphere, in which a deep baroclinic wave of zonal wavenumber 2 circles the planet at an eastward phase speed of about 70° Sol-1 (Sol is a Martian day). The regular structure of the wave gives the impression that the classical models of baroclinic instability, which describe the underlying process by a temporally unstable global wave (e.g., Eady model and Charney model), may have a direct relevance for the description of the Martian baroclinic waves. The results of the diagnostic calculations show, however, that while the Martian waves remain zonally global features at all times, there are large spatiotemporal changes in their amplitude. The most intense episodes of baroclinic energy conversion, which take place in the two great plain regions (Acidalia Planitia and Utopia Planitia), are strongly localized in both space and time. In addition, similar to the situation for terrestrial baroclinic waves, geopotential flux convergence plays an important role in the dynamics of the downstream-propagating unstable waves. © 2013 American Meteorological Society.

  16. A new tracking mode for improved Martian gravity field measurement

    Science.gov (United States)

    Yan, Jianguo; Yang, Xuan; Hao, Weifeng; Ye, Mao; Li, Fei; Qu, Chunkai; Deng, Qingyun; Jin, Weitong; Barriot, Jean-Pierre

    2017-12-01

    The Martian gravity field has been improved significantly in terms of resolution, with the spatial resolution rising to 100 km and accuracy increasing up to the 110 degree and order, assisted by data collected in Mars exploration missions like MGS, MRO, and Odyssey. However, as the tracking data used for the Martian gravity field solution are from polar orbit at a low height (˜400 km), improvements in the low degree coefficients are possible with high orbiters and various inclinations. In our research, we simulate a future Chinese Mars mission, making use of its orbit, to investigate potential contributions to the Martian gravity field solution. As the Chinese Mars mission will include a lander, we investigate the same beam interferometry tracking mode for a more precise and accurate Martian gravity field solution. Our results show that this tracking mode will substantially improve the gravity field model accuracy in comparison with those models using only polar orbit data. Model accuracy is assessed by power spectrum analysis and precise orbit determination. All the simulation work are accomplished with our independent developed software. Our research will be a reference for the first Chinese Mars exploration mission.

  17. Samples from Martian craters: Origin of the Martian soil by hydrothermal alteration of impact melt deposits and atmospheric interactions with ejecta during crater formation

    Science.gov (United States)

    Newsom, Horton E.

    1988-01-01

    The origin of the Martian soil is an important question for understanding weathering processes on the Martian surface, and also for understanding the global geochemistry of Mars. Chemical analyses of the soil will provide an opportunity to examine what may be a crustal average, as studies of loess on the Earth have demonstrated. In this regard the origin of the Martian soil is also important for understanding the chemical fractionations that have affected the composition of the soil. Several processes that are likely to contribute to the Martian soil are examined.

  18. Failure of Sterne- and Pasteur-like strains of Bacillus anthracis to replicate and survive in the urban bluebottle blow fly Calliphora vicina under laboratory conditions.

    Directory of Open Access Journals (Sweden)

    Britta von Terzi

    Full Text Available This study aimed to elucidate the bacteriological events occurring within the gut of Calliphora vicina, selected as the European representative of blow flies held responsible for the spread of anthrax during epidemics in certain parts of the world. Green-fluorescent-protein-carrying derivatives of Bacillus anthracis were used. These lacked either one of the virulence plasmids pXO1 and pXO2 and were infected, or not infected, with a worm intestine phage (Wip4 known to influence the phenotype and survival of the pathogen. Blood meals were prepared for the flies by inoculation of sheep blood with germinated and, in case of pXO2+ strains, encapsulated cells of the four B. anthracis strains. After being fed for 4 h an initial 10 flies were externally disinfected with peracetic acid to ensure subsequent quantitation representing ingested B. anthracis only. Following neutralization, they were crushed in sterile saline. Over each of the ensuing 7 to 10 days, 10 flies were removed and processed the same way. In the absence of Wip4, strains showed steady declines to undetectable in the total B. anthracis counts, within 7-9 days. With the phage infected strains, the falls in viable counts were significantly more rapid than in their uninfected counterparts. Spores were detectable in flies for longer periods than vegetative bacteria. In line with the findings in both biting and non-biting flies of early workers our results indicate that B. anthracis does not multiply in the guts of blow flies and survival is limited to a matter of days.

  19. Field Studies of Gullies and Pingos on Svalbard - a Martian Analog.

    Science.gov (United States)

    Carlsson, E.; Johannsson, H. A. B.; Johnsson, A.; Heldmann, J. L.; McKay, C. P.; Olvmo, M.; Johansson, L.; Fredriksson, S.; Schmidt, H. T.; McDaniel, S.; Reiss, D.; Hiesinger, H.; Hauber, E.; Zanetti, M.

    2008-09-01

    additional morphometric measurements will be performed, including a more thorough investigation of soil/ground characteristics in order to link these to local climate conditions. From these observations we expect to derive correlations between gully morphology and environmental parameters, which can be used to help determine whether the gullies on Mars were caused by processes related to similar circumstances in the icerich permafrost on Svalbard. Close to the gully sites on Svalbard there are pingo formations and tundra polygons and during the summer of 2008 we intend to investigate these further and compare them with Martian analogs. This will give us a chance to study a range of landforms with permafrost affinity and put them into a context of periglacial development on Mars. A survey of the microflora ranging over the length and width of the Svalbard gullies will also be conducted using a battery of exo-enzyme assays commonly used to identify extremophile organisms. These surveys will be used to design experiments to predict the distribution of aquifer-bound micro-organisms immediately following a gully forming outburst of water from such a aquifer. Adjacent terrain along the gullies will be used as a control. Aknowledgements: This project is financed by the Swedish National Space Board. References: [1] Malin, M.C. and Edgett K.S. (2000), Science, 288, 2330-2335. [2] Heldmann, J.L. and Mellon, M.T. (2004), Icarus, 168, 285-304. [3] Reiss, D. et al. (2004), J. Geophys. Res., 109, [4] Malin, M. et al. (2006), Science, 314, 1573-1577. [5] Musselwhite, D.S. et al., (2001), Geophys. Res. Lett., 28, 1283-1285. [6] Mellon, M.T. and Phillips, R.J. (2001), J. Geophys. Res., 106, 23165- 23179. [7] Costard, F. et al., (2002), Science, 295, 110-113. [8] Treiman, A.H. (2003), J. Geophys. Res., 108. [9] Christensen, P.R. (2003), Nature, 422, 45-48. [10] Gaidos, E.J. (2001), Icarus, 153, 218-223. [11] Dudas, C.M. et al. (2008), Geophys. Res. Lett., 35, [12] Heldmann, J.L. et al. (2007

  20. Durham, North Carolina, Students Study Martian Volcanism

    Science.gov (United States)

    2008-01-01

    This image of the wall of a graben a depressed block of land between two parellel faults in Tyrrhena Terra, in Mars' ancient southern highlands, was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0914 UTC (4:14 a.m. EST) on February 6, 2008, near 17.3 degrees south latitude, 95.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 35 meters (115 feet) across. The region covered is just over 10 kilometers (6.2 miles) wide at its narrowest point. This image was part of an investigation planned by students in four high schools in Durham, North Carolina. The students are working with the CRISM science team in a project called the Mars Exploration Student Data Teams (MESDT), which is part of NASA's Mars Public Engagement Program and Arizona State University's Mars Education Program. Starting with a medium-resolution map of the area, taken as part of CRISM's 'multispectral survey' campaign to map Mars in 72 colors at 200 meters (660 feet) per pixel, the students identified a key rock outcrop to test their hypothesis that the irregular depression was formed by Martian volcanism. They provided the coordinates of the target to CRISM's operations team, who took a high-resolution image of the site. The Context Imager (CTX) accompanied CRISM with a 6 meter (20 feet) per pixel, high-resolution image to sharpen the relationship of spectral variations to the underlying surface structures. The Durham students worked with a mentor on the CRISM team to analyze the data, and presented their results at the 39th Lunar and Planetary Science Conference, held in League City, Texas, on March 10-14, 2008. The upper panel of the image shows the location of the CRISM data and the surrounding, larger CTX image, overlain on an image mosaic taken by the Thermal Emission Imaging System (THEMIS) on Mars Odyssey. The mosaic has been color-coded for elevation using data from the Mars Orbiter Laser

  1. Architectural concepts of Martian bases built: of domes, around greenhouses and into slopes -the human aspect and the technology

    Science.gov (United States)

    Kozicki, Janek; Kozicka, Joanna

    Human missions to Mars are a special kind of space missions due to their long duration. The human aspect of such missions becomes as important as the technological one. The need for a human friendly and comfortable habitat arises. Studies of human behavior in ICEs have shown that larger groups of people mean a lower occurrence of conflicts. However, for a larger crew a larger habitat has to be designed -a Martian base. The research deals with psychological, sociological and technological aspects influencing the architectural design of a Martian Base. Extreme conditions present on Mars demand a partic-ular approach to technological and architectural design. To reduce the cost of building a bigger habitat, low cost solutions have been inquired into. A series of analyses has been performed to identify the best architectural solutions for a Martian base. A review of existing technologies and extreme condition habitats (both terrestrial and extraterrestrial) has revealed solutions that are the most reliable and efficient ones. Additionally, innovative technologies have been analyzed in search of the best candidates for actual base construction. Low cost solutions have been prioritized in the process. An in-depth study of architectural problems inherent in the design of a Martian base has resulted in a number of guidelines for the architect. The main ones are introduced in this review. Based on them, several concepts have been drafted as examples of user-friendly and aesthetically pleasing habitats. They are discussed in the following order: habitats made of domes, those built around greenhouses and those situated in sloping terrain. One of them is presented in detail, including interior design.

  2. Martian aeolian slipface dynamics: 3D airflow modelling and sediment surface changes

    Science.gov (United States)

    Cornwall, Carin; Jackson, Derek; Bourke, Mary; Cooper, Andrew

    2017-04-01

    In December 2015, the Curiosity rover relayed images of the Namib dune slipface in Gale Crater and presented a unique opportunity for direct comparison to terrestrial aeolian dynamics. These images delivered critical ground truth data of martian aeolian dynamics improving morphometric studies of slipface grainflow activity and aeolian modelling. The Namib dune slipface images reveal many comparable grainflow morphologies to that of terrestrial slipfaces suggesting similar mechanisms for sediment transportation and dune migration. However, much is still unknown about the specifics of martian dune migration including possible 'seasonality' of activity, the contribution of actively migrating ripples to sediment redistribution, and estimates of sediment volume moved annually. One of the leading goals in investigating aeolian processes on Mars is to explore the boundary conditions of sediment transport, accumulation, and dune morphology in relation to wind regime as well as to quantify migration rates and sediment flux. We plan to address these goals by combining terrestrial field observations, 3D computational fluid dynamics (CFD) modelling and remote sensing data. Complex, small scale wind patterns and grainflow processes on terrestrial and martian dunes will be investigated to constrain grain flow magnitudes and frequencies that occur on slipface slopes of dunes to improve estimates of martian dune field migration and sediment flux related to wind velocity and flow patterns. Using CFD modelling, we will investigate the interaction between wind velocity, flow patterns and sediment transport at the bedform scale using real wind data collected on Mars to provide a way to examine potential triggers of processes on slipface slopes of dunes. A series of ground-based, high resolution laser scans have been collected in the Maspalomas dune field in Gran Canaria, Spain to investigate grainflow frequency, morphology and slipface advancement. Analysis of these laser scans and

  3. Ephemeral Liquid Water at the Surface of Martian North Polar Cap

    Science.gov (United States)

    Losiak, Anna; Czechowski, Leszek; Velbel, Michael A.

    2015-04-01

    Formation of large, young gypsum deposits within the Olympia Planum region has been an unsolved riddle since its discovery [1]. It was proposed that gypsum was formed by precipitation of water emanating from polar layered deposits [2]. However, it is improbable that a large amount of bulk water could exist under current Martian low atmospheric pressure sufficiently long to form the observed deposits [3]. One of the proposed solutions to this problem is that gypsum is formed due to weathering in the ice [3, 4, 5, 6]. However none of the previous papers have described this process in detail, tested whether it is possible under current Martian conditions, and defined the environmental properties required for this process to occur. The aim of this paper is to determine if solar irradiation available currently at the North Polar Cap (NPC) is sufficient to heat a basaltic dust grain enough to melt a thin layer of glacial ice located directly beneath it. The numerical model used here is based on a one dimensional, time-dependent equation of heat transfer [8]. The model is applicable for grains exposed on the south-facing side of the NPC spiral troughs, during the warmest days of the year (with average or low amount of dust in the atmosphere), when surface temperature reaches 215 K and solar radiation delivers >260 W m^-2 (on the inclined surface). Our calculations show that during the warmest days of summer, pure water-ice located below a dark dust particle lying on the equatorial-facing slopes of the Martian NPC can be melted. Melting occurs over a wide range of used parameters which shows that this phenomenon is relatively common (albeit localized). Our research shows that on the Martian NPC there can be a sufficient amount of transient, metastable liquid water for evaporites such as gypsum to form, as was hypothesized by [3, 4, 5, 6]. Additionally, bulk water surrounding dust grains near the surface and precipitating evaporitic minerals makes the NPC one of the most

  4. Architectural design proposal for a Martian base to continue NASA Mars Design Reference Mission

    Science.gov (United States)

    Kozicki, Janek

    The issue of extraterrestrial bases has recently been a very vivid one. There are orbital stations currently existing and humans will travel to Mars around 2030. They will need stations established there, which will provide them the proper living conditions. Firstly, it might be a small module brought from Earth (e.g. NASA Mars Design Reference Mission module (DRM)), in later stages equivalents of Earth houses may be built from local resources. The goal of this paper is to propose an architectural design for an intermediate stage — for a larger habitable unit transported from Earth. It is inspired by terrestrial portable architecture ideas. A pneumatic structure requires small volume during transportation. However, it provides large habitable space after deployment. It is designed for transport by DRM transportation module and its deployment is considerable easy and brief. An architectural solution analogous to a terrestrial house with a studio and a workshop was assumed. Its form was a result of technical and environmental limitations, and the need for an ergonomic interior. The spatial placement of following zones was carefully considered: residential, agricultural and science, as well as a garage with a workshop, transportation routes, and a control and communication center. The issues of Life Support System, energy, food, water and waste recycling were also discussed. This Martian base was designed to be crewed by a team of eight people to stay on Mars for at least 1.5 year. An Open Plan architectural solution was assumed in pneumatic modules, with a high level of modularity. Walls of standardized sizes with zip-fasteners allow free rearrangement of the interior to adapt to a new situation (e.g. damage of one of the pneumatic modules or a psychological ,,need of a change"). The architectural design focuses on ergonomic and psychological aspects of longer stay in hostile Martian environment. This solution provides Martian crew with a comfortable habitable

  5. Studies of Magmatic Inclusions in the Basaltic Martian Meteorites Shergotty, Zagami, EETA 79001 and QUE 94201

    Science.gov (United States)

    Harvey, Ralph P.; McKay, Gordon A.

    1997-01-01

    Currently there are 12 meteorites thought by planetary scientists to be martian samples, delivered to the Earth after violent impacts on that planet's surface. Of these 12 specimens, 4 are basaltic: Shergotty, Zagami, EETA 79001 and QUE 94201. Basalts are particularly important rocks to planetary geologists- they are the most common rocks found on the surfaces of the terrestrial planets, representing volcanic activity of their parent worlds. In addition, because they are generated by partial melting of the mantle and/or lower crust, they can serve as guide posts to the composition and internal processes of a planet. Consequently these four meteorites can serve as 'ground-truth' representatives of the predominant volcanic surface rocks of Mars, and offer researchers a glimpse of the magmatic history of that planet. Unfortunately, unraveling the parentage of a basaltic rock is not always straightforward. While many basalts are simple, unaltered partial melts of the mantle, others have undergone secondary processes which change the original parental chemistry, such as assimilation of other crustal rocks, mixing with other magmas, accumulation, re-equilibration between mineral species after crystallization, loss of late-stage magmatic fluids and alteration by metamorphic or metasomatic processes. Fortunately, magmatic inclusions can trap the evolving magmatic liquid, isolating it from many of these secondary processes and offering a direct look at the magma during different stages of development. These inclusions form when major or minor phases grow skeletally, surrounding small amounts of the parental magma within pockets in the growing crystal. The inclusion as a whole (usually consisting of glass with enclosed crystals) continues to represent the composition of the parental magma at the time the melt pocket closed, even when the rock as a whole evolves under changing conditions. The four basaltic martian meteorites contain several distinct generations of melt

  6. Stability of the Martian atmosphere: Is heterogeneous catalysis essential?

    Science.gov (United States)

    Atreya, Sushil K.; Gu, Zhen Gang

    1994-01-01

    A comprehensive homogeneous gas phase photochemical model is developed to study the problem of stability of the Martian atmosphere. The one-dimensional model extends from the ground up to 220 km, passing through the homopause at 125 km. The model thus couples the lower (neutral) atmosphere to the ionosphere above which provides significant downward flux of carbon monoxide and oxygen atoms. It is concluded on the basic of currently accepted values for globally and seasonally averaged water vapor abundance, dust opacity and the middle atmospheric eddy mixing coefficient, as well as the relevant laboratory data (particularly the temperature dependence of CO2 absorption cross section and the rate constant for CO+OH reaction), that the rate of re-formation of carbon dioxide exceeds its photolytic destruction rate by about 40%. Furthermore, it is found that this result is virtually independent of the choice of eddy mixing coefficient, unless its value in the middle atmosphere exceeds 10(exp 8) sq cm/sec or is far smaller than 10(exp 5)sq cm/sec, or the dust opacity, unless it exceeds unity, or the water vapor mixing ratio at the surface, unless it is far smaller (less than or = 1 ppm) or far greater (greater than or = 500 ppm) than the average value (approximately 150 ppm). Since none of these extremes represent globally and seasonally averaged conditions on Mars, we propose that the present model requires existence of a mechanism to throttle down the recycling rate of carbon dioxide on Mars. Therefore, it is suggested that a heterogeneous process which provides a sink to the species that participate in the recycling of CO2, i.e., H2O, H2O2, OH, CO or O, in particular, may be necessary to bring about the balance between the CO2 recycling rate and its photolytic destruction rate. Aerosols of dust or ice (pure or doped water or carbon dioxide ice present in the atmosphere of Mars) can provide the appropriate adsorption sites for the above heterogeneous process. Despite our

  7. Survival Analysis

    CERN Document Server

    Miller, Rupert G

    2011-01-01

    A concise summary of the statistical methods used in the analysis of survival data with censoring. Emphasizes recently developed nonparametric techniques. Outlines methods in detail and illustrates them with actual data. Discusses the theory behind each method. Includes numerous worked problems and numerical exercises.

  8. Modelling survival

    DEFF Research Database (Denmark)

    Ashauer, Roman; Albert, Carlo; Augustine, Starrlight

    2016-01-01

    well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates...

  9. Impact of inulin and okara on Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 viability in a fermented soy product and probiotic survival under in vitro simulated gastrointestinal conditions

    OpenAIRE

    Bedani, Raquel [UNESP; Rossi, Elizeu Antonio [UNESP; Isay Saad, Susana Marta

    2013-01-01

    The effect of inulin and/or okara flour on Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 viability in a fermented soy product (FSP) and on probiotic survival under in vitro simulated gastrointestinal conditions were investigated throughout 28 days of storage at 4 °C. Employing a 22 design, four FSP trials were produced from soymilk fermented with ABT-4 culture (La-5, Bb-12, and Streptococcus thermophilus): FSP (control); FSP-I (with inulin, 3 g/100 mL of soymilk); FSP-O (w...

  10. Encapsulation of probiotic Bifidobacterium longum BIOMA 5920 with alginate-human-like collagen and evaluation of survival in simulated gastrointestinal conditions.

    Science.gov (United States)

    Su, Ran; Zhu, Xiao-Li; Fan, Dai-Di; Mi, Yu; Yang, Chan-Yuan; Jia, Xin

    2011-12-01

    Alginate (ALg)-human-like collagen (HLC) microspheres were prepared by the technology of electrostatic droplet generation in order to develop a biocompatible vehicle for probiotic bacteria. Microparticles were spherical with mean particle size of 400μm. The encapsulation efficiency (EE) of ALg-HLC microspheres could reach 92-99.2%. Water-soluble and fibrous human-like collagen is combined with sodium alginate through intermolecular hydrogen bonding and electrostatic force which were investigated by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC), thus the matrix of ALg-HLC was very stable. Bifidobacterium longum BIOMA 5920, as a kind of probiotic bacteria, was encapsulated with alginate-human-like collagen to survive and function in simulated gastrointestinal juice. Microparticles were very easy to degradation in simulated intestinal juices. After incubation in simulated gastric (pH 2.0, 2h), the encapsulated B. longum BIOMA 5920 numbers were 4.81 ± 0.38 log cfu/g. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Terrestrial microbes in martian and chondritic meteorites

    Science.gov (United States)

    Airieau, S.; Picenco, Y.; Andersen, G.

    2007-08-01

    Introduction: The best extraterrestrial analogs for microbiology are meteorites. The chemistry and mineralogy of Asteroid Belt and martian (SNC) meteorites are used as tracers of processes that took place in the early solar system. Meteoritic falls, in particular those of carbonaceous chondrites, are regarded as pristine samples of planetesimal evolution as these rocks are primitive and mostly unprocessed since the formation of the solar system 4.56 billion years ago. Yet, questions about terrestrial contamination and its effects on the meteoritic isotopic, chemical and mineral characteristics often arise. Meteorites are hosts to biological activity as soon as they are in contact with the terrestrial biosphere, like all rocks. A wide biodiversity was found in 21 chondrites and 8 martian stones, and was investigated with cell culture, microscopy techniques, PCR, and LAL photoluminetry. Some preliminary results are presented here. The sample suite included carbonaceous chondrites of types CR, CV, CK, CO, CI, and CM, from ANSMET and Falls. Past studies documented the alteration of meteorites by weathering and biological activity [1]-[4]. Unpublished observations during aqueous extraction for oxygen isotopic analysis [5], noted the formation of biofilms in water in a matter of days. In order to address the potential modification of meteoritic isotopic and chemical signatures, the culture of microbial contaminating species was initiated in 2005, and after a prolonged incubation, some of the species obtained from cell culture were analyzed in 2006. The results are preliminary, and a systematic catalog of microbial contaminants is developing very slowly due to lack of funding. Methods: The primary method was cell culture and PCR. Chondrites. Chondritic meteorite fragments were obtained by breaking stones of approximately one gram in sterile mortars. The core of the rocks, presumably less contaminated than the surface, was used for the present microbial study, and the

  12. 78 FR 66317 - Special Conditions: Learjet Inc. Model LJ-200-1A10; Airplane Fuselage Post-Crash Fire Survivability

    Science.gov (United States)

    2013-11-05

    ... materials in the construction of its fuselage and wings. In accordance with Sec. 21.16, fuselage structure... feature associated with advanced composite materials in the construction of its fuselage and wings. The... construction of its fuselage and wings. This proposed special condition is necessary to ensure a level of...

  13. Survival or growth of inoculated Escherichia coli O157:H7 and Salmonella on yellow onions (Allium cepa) under conditions simulating food service and consumer handling and storage.

    Science.gov (United States)

    Lieberman, Vanessa M; Zhao, Irene Y; Schaffner, Donald W; Danyluk, Michelle D; Harris, Linda J

    2015-01-01

    Whole and diced yellow onions (Allium cepa) were inoculated with five-strain cocktails of rifampin-resistant Escherichia coli O157:H7 or Salmonella and stored under conditions to simulate food service or consumer handling. The inoculum was grown in broth (for both whole and diced onion experiments) or on agar plates (for whole onion experiments). Marked circles (3.3 cm in diameter) on the outer papery skin of whole onions were spot inoculated (10 μl in 10 drops) at 7 log CFU per circle, and onions were stored at 4°C, 30 to 50 % relative humidity, or at ambient conditions (23°C, 30 to 50 % relative humidity). Diced onions were inoculated at 3 log CFU/g and then stored in open or closed containers at 4°C or ambient conditions. Previously inoculated and ambient-stored diced onions were also mixed 1:9 (wt/wt) with refrigerated uninoculated freshly diced onions and stored in closed containers at ambient conditions. Inoculated pathogens were recovered in 0.1 % peptone and plated onto selective and nonselective media supplemented with 50 μg/ml rifampin. Both E. coli O157:H7 and Salmonella populations declined more rapidly on onion skins when the inoculum was prepared in broth rather than on agar. Agar-prepared E. coli O157:H7 and Salmonella declined by 0.4 and 0.3 log CFU per sample per day, respectively, at ambient conditions; at 4°C the rates of reduction were 0.08 and 0.06 log CFU per sample per day for E. coli O157:H7 and Salmonella, respectively. Populations of E. coli O157:H7 and Salmonella did not change over 6 days of storage at 4°C in diced onions. Lag times of 6 to 9 h were observed with freshly inoculated onion at ambient conditions; no lag was observed when previously inoculated and uninoculated onions were mixed. Growth rates at ambient conditions were 0.2 to 0.3 log CFU/g/h for E. coli O157:H7 and Salmonella in freshly inoculated onion and 0.2 log CFU/g/h in mixed product. Diced onions support pathogen growth and should be kept refrigerated.

  14. Assessment of the turbulence parameterization schemes for the Martian mesoscale simulations

    Science.gov (United States)

    Temel, Orkun; Karatekin, Ozgur; Van Beeck, Jeroen

    2016-07-01

    Turbulent transport within the Martian atmospheric boundary layer (ABL) is one of the most important physical processes in the Martian atmosphere due to the very thin structure of Martian atmosphere and super-adiabatic conditions during the diurnal cycle [1]. The realistic modeling of turbulent fluxes within the Martian ABL has a crucial effect on the many physical phenomena including dust devils [2], methane dispersion [3] and nocturnal jets [4]. Moreover, the surface heat and mass fluxes, which are related with the mass transport within the sub-surface of Mars, are being computed by the turbulence parameterization schemes. Therefore, in addition to the possible applications within the Martian boundary layer, parameterization of turbulence has an important effect on the biological research on Mars including the investigation of water cycle or sub-surface modeling. In terms of the turbulence modeling approaches being employed for the Martian ABL, the "planetary boundary layer (PBL) schemes" have been applied not only for the global circulation modeling but also for the mesoscale simulations [5]. The PBL schemes being used for Mars are the variants of the PBL schemes which had been developed for the Earth and these schemes are either based on the empirical determination of turbulent fluxes [6] or based on solving a one dimensional turbulent kinetic energy equation [7]. Even though, the Large Eddy Simulation techniques had also been applied with the regional models for Mars, it must be noted that these advanced models also use the features of these traditional PBL schemes for sub-grid modeling [8]. Therefore, assessment of these PBL schemes is vital for a better understanding the atmospheric processes of Mars. In this framework, this present study is devoted to the validation of different turbulence modeling approaches for the Martian ABL in comparison to Viking Lander [9] and MSL [10] datasets. The GCM/Mesoscale code being used is the PlanetWRF, the extended version

  15. Formation and evolution of Martian gullies: a terrestrial perspective

    Science.gov (United States)

    Haas, T. D.

    2016-12-01

    Martian Gullies (alcove-fan systems) are among the youngest landforms that may have formed by liquid water on Mars, and therefore of critical importance in resolving the planet's most recent climatic history. Water-free sediment flows, often associated to CO2 ice, debris flows and fluvial flows have all been identified in gullies. These processes require different amounts of liquid water, and therefore their contribution to gully-formation is of key importance for climatic inferences. In contrast to CO2-aided flows, there are terrestrial analogues for debris flows and fluvial flows. Here I compare the morphology, morphometry and sedimentology of the surface and subsurface deposits of Martian gullies as seen on HiRISE imagery to terrestrial analogues in order to determine their formative processes and the climate in which Martian gullies formed. Terrestrial analogues from the hyperarid Atacama Desert (Chile) and Death Valley (USA), the arctic region of Svalbard and a small-scale experimental setup are visited to do so. Secondly, a sediment budget analysis is performed on geophysical-flow deposits in Martian gullies, to infer their return period as well as the amounts of water needed for their formation. Finally, the effect of time on Martian gully evolution is evaluated by comparing the size and morphology of gullies and associated landforms with their host crater age (and thus their time of potential activity). In short, the sedimentology in vertical exposures in Martian gullies is consistent with a formation by debris flows, while surficial debris-flow signatures have often been removed by erosion. Boulder mobility calculations imply that significant gully formation by fluvial sheetfloods is unlikely. Sediment budget analyses of debris-flow deposits in Istok crater imply that debris flows occurred at Earth-like frequencies during high-obliquity periods in the last million years on Mars and that melting must have yielded centimeters of liquid water in the gully

  16. Medical Issues for a Human Mission to Mars and Martian Surface Expeditions

    Science.gov (United States)

    Jones, J. A.; Barratt, M.; Effenhauser, R.; Cockell, C. S.; Lee, P.

    The medical issues for an exploratory class mission to Mars are myriad and challenging. They include hazards from the space environment, such as space vacuum and radiation; hazards on the planetary surface such as micrometeoroids and Martian dust, and constitutional medical hazards, like appendicitis and tooth abscess. They include hazards in the transit vehicle like foreign bodies and toxic atmospheres, and hazards in the habitat like decompression and combustion events. They also include human physiological adaptation to variable conditions of reduced gravity and prolonged isolation and confinement. The health maintenance program for a Mars mission will employ strategies of disease prevention, early detection, and contingency management, to mitigate the risks of spaceflight and exploration. Countermeasures for altered gravity conditions will allow crewmembers to maintain high levels of performance and nominal physiologic functioning. Despite all of these issues, given sufficient redundancy in on-board life support systems, there are no medical show-stoppers for the first human exploratory class missions.

  17. Can perchlorates be transformed to hydrogen peroxide (H2O2) products by cosmic rays on the Martian surface?

    Science.gov (United States)

    Crandall, Parker B.; Góbi, Sándor; Gillis-Davis, Jeffrey; Kaiser, Ralf I.

    2017-09-01

    Due to their oxidizing properties, perchlorates (ClO4-) are suggested by the planetary science community to play a vital role in the scarcity of organics on the Martian surface. However, alternative oxidation agents such as hydrogen peroxide (H2O2) have received surprisingly little attention. In this study, samples of magnesium perchlorate hexahydrate (Mg(ClO4)2 · 6H2O) were exposed to monoenergetic electrons and D2+ ions separately, sequentially, and simultaneously to probe the effects of galactic cosmic ray exposure of perchlorates and the potential incorporation of hydrogen (deuterium) into these minerals. The experiments were carried out under ultrahigh-vacuum conditions at 50 K, after which the samples were slowly heated to 300 K while the subliming products were monitored by a quadrupole mass spectrometer. In all cases, molecular oxygen (O2) was detected upon the onset of irradiation and also during the warmup phase. In case of a simultaneous D2+-electron exposure, deuterated water (D2O) and deuterium peroxide (D2O2) were also detected in the warmup phase, whereas only small amounts of D2O2 were found after an exclusive D2+ irradiation. These experiments yield the first data identifying hydrogen peroxide as a potential product in the interaction of cosmic rays with perchlorates in the Martian regolith revealing that perchlorates are capable of producing multiple oxidizing agents (O2 and D2O2) that may account for the destruction of organics on the Martian surface.

  18. Mineralization of Bacteria in Terrestrial Basaltic Rocks: Comparison With Possible Biogenic Features in Martian Meteorite Allan Hills 84001

    Science.gov (United States)

    Thomas-Keprta, K. L.; McKay, D. S.; Wentworth, S. J.; Stevens, T. O.; Taunton, A. E.; Allen, C. C.; Gibson, E. K., Jr.; Romanek, C. S.

    1998-01-01

    The identification of biogenic features altered by diagenesis or mineralization is important in determining whether specific features in terrestrial rocks and in meteorites may have a biogenic origin. Unfortunately, few studies have addressed the formation of biogenic features in igneous rocks, which may be important to these phenomena, including the controversy over possible biogenic features in basaltic martian meteorite ALH84001. To explore the presence of biogenic features in igneous rocks, we examined microcosms growing in basaltic small-scale experimental growth chambers or microcosms. Microbial communities were harvested from aquifers of the Columbia River Basalt (CRB) group and grown in a microcosm containing unweathered basalt chips and groundwater (technique described in. These microcosms simulated natural growth conditions in the deep subsurface of the CRB, which should be a good terrestrial analog for any putative martian subsurface ecosystem that may have once included ALH84001. Here we present new size measurements and photomicrographs comparing the putative martian fossils to biogenic material in the CRB microcosms. The range of size and shapes of the biogenic features on the CRB microcosm chips overlaps with and is similar to those on ALH84001 chips. Although this present work does not provide evidence for the biogenicity of ALH84001 features, we believe that, based on criteria of size, shape, and general morphology, a biogenic interpretation for the ALH84001 features remains plausible.

  19. Alteration of the Martian Surface Through Time: A Reaction Path Modeling Approach

    Science.gov (United States)

    Ridley, W. I.; Plumlee, G. S.; Debraal, J. D.; Reed, M. H.

    1995-09-01

    We have performed preliminary geochemical reaction path calculations [1] that attempt to model reasonable martian geologic processes under various climatic conditions postulated for Mars during its planetary evolution [2]. Weathering and fluid evaporation and freezing are discussed here. Under current Earth conditions, 25 degrees C rainwater in equilibrium with the atmosphere has a calculated pH=5.66, dissolved O2=2.5x10^-4 mole/kg, and dissolved CO2=1.3x10^-5 mole/kg. In contrast, martian rainwater in a postulated early, warm and wet climate would have lower pH,, higher dissolved CO2, and lower dissolved oxygen. For instance, in a martian atmosphere with pCO2=2.2 bar [3] and pO2=10^-5 bar, rainwater is calculated to have pH=3.96, dissolved CO2 of 7.5x10^-2 mole/kg, and dissolved O2=1.3x10^-8 mole/kg. If, under these climatic conditions, there was also extensive basaltic volcanism, then rainwater would be further modified chemically by solution of volcanic gases to form acid rain. For example, we can model this process using a Kilauea gas composition, in mole percent (H2O=57.8; HCl=0.9; SO2=17.4; CO2=21.6; H2S=0.2; H2=1.0), and assume the resultant fluid is buffered by atmospheric CO2. Addition of only 0.1 gram of gas to 1 kgram of ancient rainwater reduces the pH to 3.07 and dramatically increases dissolved SO4- (3.8x10^-4 mole/kg), H2S[aq] (1.3x10^-4 mole/kg) and Cl- (4.4x10^-5 mole/kg). Weathering minerals formed by reaction of the above fluid types with martian basalts can vary significantly depending upon initial fluid acidity and solute content. Acid rain and "normal" rain (buffered under high pCO2 conditions) initially alter martian basalt (modeled as the Chassigny parent composition [4]) to, in order of decreasing abundance: Fe-smectite (+/- ferrihydrite), Mn hydroxide, kaolinite, apatite, chalcedony at pH 5 then dolomite, calcite, K-feldspar, and dawsonite also precipitate. An important aspect of this modeling is that acid rain can produce larger volumes

  20. Dispersal and Survival of Flavobacterium psychrophilum Phages In Vivo in Rainbow Trout and In Vitro under Laboratory Conditions: Implications for Their Use in Phage Therapy

    DEFF Research Database (Denmark)

    Madsen, Lone; Bertelsen, Sif K.; Dalsgaard, Inger

    2013-01-01

    and bacterium was most prevalent in the kidney and spleen, with only minor occurrence in the brain. The experiment showed that injected phages were rapidly spread in the internal organs of the fish, also in the absence of bacteria. Parallel examination of the regulation of bacteriophage infectivity...... in controlled laboratory experiments at various environmental conditions showed that pH had only minor effects on long-term (3 months) phage infectivity within a pH range of 4.5 to 7.5, whereas phage infectivity was immediately lost at pH 3. In the absence of host cells, phage infectivity decreased by a factor...

  1. Effects of varying obliquity on Martian sublimation thermokarst landforms

    Science.gov (United States)

    Dundas, Colin M.

    2017-01-01

    Scalloped depressions in the Martian mid-latitudes are likely formed by sublimation of ice-rich ground. The stability of subsurface ice changes with the planetary obliquity, generally becoming less stable at lower axial tilt. As a result, the relative rates of sublimation and creep change over time. A landscape evolution model shows that these variations produce internal structure in scalloped depressions, commonly in the form of arcuate ridges, which emerge as depressions resume growth after pausing or slowing. In other scenarios, the formation of internal structure is minimal. Significant uncertainties in past climate and model parameters permit a range of scenarios. Ridges observed in some Martian scalloped depressions could date from obliquity lows or periods of low ice stability occurring <5 Ma, suggesting that the pits are young features and may be actively evolving.

  2. Exposed subsurface ice sheets in the Martian mid-latitudes.

    Science.gov (United States)

    Dundas, Colin M; Bramson, Ali M; Ojha, Lujendra; Wray, James J; Mellon, Michael T; Byrne, Shane; McEwen, Alfred S; Putzig, Nathaniel E; Viola, Donna; Sutton, Sarah; Clark, Erin; Holt, John W

    2018-01-12

    Thick deposits cover broad regions of the Martian mid-latitudes with a smooth mantle; erosion in these regions creates scarps that expose the internal structure of the mantle. We investigated eight of these locations and found that they expose deposits of water ice that can be >100 meters thick, extending downward from depths as shallow as 1 to 2 meters below the surface. The scarps are actively retreating because of sublimation of the exposed water ice. The ice deposits likely originated as snowfall during Mars' high-obliquity periods and have now compacted into massive, fractured, and layered ice. We expect the vertical structure of Martian ice-rich deposits to preserve a record of ice deposition and past climate. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  3. Martian Methane From a Cometary Source: A Hypothesis

    Science.gov (United States)

    Fries, M.; Christou, A.; Archer, D.; Conrad, P.; Cooke, W.; Eigenbrode, J.; ten Kate, I. L.; Matney, M.; Niles, P.; Sykes, M.; hide

    2016-01-01

    In recent years, methane in the martian atmosphere has been detected by Earth-based spectroscopy, the Planetary Fourier Spectrometer on the ESA Mars Express mission, and the NASA Mars Science Laboratory. The methane's origin remains a mystery, with proposed sources including volcanism, exogenous sources like impacts and interplanetary dust, aqueous alteration of olivine in the presence of carbonaceous material, release from ancient deposits of methane clathrates, and/or biological activity. An additional potential source exists: meteor showers from the emission of large comet dust particles could generate martian methane via UV pyrolysis of carbon-rich infall material. We find a correlation between the dates of Mars/cometary orbit encounters and detections of methane on Mars. We hypothesize that cometary debris falls onto Mars during these interactions, generating methane via UV photolysis.

  4. Mineral Biomarkers in Martian Meteorite Allan Hills 84001?

    Science.gov (United States)

    Thomas-Keprta, K. L.; Bazylinski, D. A.; Wentworth, S. J.; McKay, D. S.; Golden, D. C.; Gibson, E. K., Jr.; Romanek, C. S.

    1998-01-01

    The occurrence of fine-grained magnetite in the Fe-rich rims surrounding carbonate globules in the martian meteorite ALH84001, originally described in , have been proposed as fossil remains of primitive martian organisms. Here we report observations on size and shape distributions of magnetites from ALH84001 and compare them to biogenic and inorganic magnetite crystals of terrestrial origin. While some magnetite morphology is not unequivocally diagnostic for its biogenicity, such as cubodial forms of magnetite, which are common in inorganically formed magnetites, other morphologies of magnetite (parallel-epiped or elongated prismatic and arrowhead forms) are more likely signatures of biogenic activity. Some ALH 84001 magnetite particles described below have unique morphology and length-to-width ratios that are indistinguishable from a variety of terrestrial biogenic magnetite and distinct from all known inorganic forms of magnetite.

  5. Martian geomorphology and its relation to subsurface volatiles

    Science.gov (United States)

    Clifford, Stephen M. (Editor); Rossbacher, Lisa A. (Editor); Zimbelman, James R. (Editor)

    1986-01-01

    Martian volatile inventory, planetary climatic and atmospheric evolution, and the interpretation of various remote sensing data were discussed. A number of morphologies that were cited as potential indicators of subsurface volatiles were reviewed. Rampart craters and terrain softening were the focus of more in-depth discussion because of the popular attention they have received and the fact that their areal distributions are by far the most extensive of all the proposed indicators.

  6. Pressure effects on martian crustal magnetization near large impact basins

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther; Connerly, J. E. P.; Ness, N. F.; Acuna, M. H.

    2004-01-01

    Roč. 39, č. 11 (2004), s. 1839-1848 ISSN 1086-9379 R&D Projects: GA AV ČR(CZ) IAA3013406 Keywords : martian magnetism * shock pressure * impact Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.673, year: 2004 http:// eso ads. eso .org//full/2004M%26PS...39.1839K/0001839.000.html

  7. A Martian origin for the Mars Trojan asteroids

    Science.gov (United States)

    Polishook, D.; Jacobson, S. A.; Morbidelli, A.; Aharonson, O.

    2017-08-01

    Seven of the nine known Mars Trojan asteroids belong to an orbital cluster1,2 named after its largest member, (5261) Eureka. Eureka is probably the progenitor of the whole cluster, which formed at least 1 Gyr ago3. It has been suggested3 that the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect spun up Eureka, resulting in fragments being ejected by the rotational-fission mechanism. Eureka's spectrum exhibits a broad and deep absorption band around 1 μm, indicating an olivine-rich composition4. Here we show evidence that the Trojan Eureka cluster progenitor could have originated as impact debris excavated from the Martian mantle. We present new near-infrared observations of two Trojans ((311999) 2007 NS2 and (385250) 2001 DH47) and find that both exhibit an olivine-rich reflectance spectrum similar to Eureka's. These measurements confirm that the progenitor of the cluster has an achondritic composition4. Olivine-rich reflectance spectra are rare amongst asteroids5 but are seen around the largest basins on Mars6. They are also consistent with some Martian meteorites (for example, Chassigny7) and with the material comprising much of the Martian mantle8,9. Using numerical simulations, we show that the Mars Trojans are more likely to be impact ejecta from Mars than captured olivine-rich asteroids transported from the main belt. This result directly links specific asteroids to debris from the forming planets.

  8. Advanced concept for a crewed mission to the martian moons

    Science.gov (United States)

    Conte, Davide; Di Carlo, Marilena; Budzyń, Dorota; Burgoyne, Hayden; Fries, Dan; Grulich, Maria; Heizmann, Sören; Jethani, Henna; Lapôtre, Mathieu; Roos, Tobias; Castillo, Encarnación Serrano; Schermann, Marcel; Vieceli, Rhiannon; Wilson, Lee; Wynard, Christopher

    2017-10-01

    This paper presents the conceptual design of the IMaGInE (Innovative Mars Global International Exploration) Mission. The mission's objectives are to deliver a crew of four astronauts to the surface of Deimos and perform a robotic exploration mission to Phobos. Over the course of the 343 day mission during the years 2031 and 2032, the crew will perform surface excursions, technology demonstrations, In Situ Resource Utilization (ISRU) of the Martian moons, as well as site reconnaissance for future human exploration of Mars. This mission design makes use of an innovative hybrid propulsion concept (chemical and electric) to deliver a relatively low-mass reusable crewed spacecraft (approximately 100 mt) to cis-martian space. The crew makes use of torpor which minimizes launch payload mass. Green technologies are proposed as a stepping stone towards minimum environmental impact space access. The usage of beamed energy to power a grid of decentralized science stations is introduced, allowing for large scale characterization of the Martian environment. The low-thrust outbound and inbound trajectories are computed through the use of a direct method and a multiple shooting algorithm that considers various thrust and coast sequences to arrive at the final body with zero relative velocity. It is shown that the entire mission is rooted within the current NASA technology roadmap, ongoing scientific investments and feasible with an extrapolated NASA Budget. The presented mission won the 2016 Revolutionary Aerospace Systems Concepts - Academic Linkage (RASC-AL) competition.

  9. Geochemistry of Martian Meteorites and the Petrologic Evolution of Mars

    Science.gov (United States)

    Mittlefehldt, D. W.

    2002-01-01

    Mafic igneous rocks serve as probes of the interiors of their parent bodies - the compositions of the magmas contain an imprint of the source region composition and mineralogy, the melting and crystallization processes, and mixing and assimilation. Although complicated by their multifarious history, it is possible to constrain the petrologic evolution of an igneous province through compositional study of the rocks. Incompatible trace elements provide one means of doing this. I will use incompatible element ratios of martian meteorites to constrain the early petrologic evolution of Mars. Incompatible elements are strongly partitioned into the melt phase during igneous processes. The degree of incompatibility will differ depending on the mineral phases in equilibrium with the melt. Most martian meteorites contain some cumulus grains, but nevertheless, incompatible element ratios of bulk meteorites will be close to those of their parent magmas. ALH 84001 is an exception, and it will not be discussed. The martian meteorites will be considered in two groups; a 1.3 Ga group composed of the clinopyroxenites and dunite, and a younger group composed of all others.

  10. Infiltration of Martian outflow channel floodwaters into lowland cavernous systems

    Science.gov (United States)

    Rodriguez, J. Alexis P.; Bourke, Mary; Tanaka, Kenneth L.; Miyamoto, Hideaki; Kargel, Jeffrey; Baker, Victor; Fairén, Alberto G.; Davies, Richard J.; Bridget, Lynne; Santiago, Rogelio Linares; Hernández, Mario Zarroca; Berman, Daniel C.

    2012-11-01

    The hydrosphere of Mars has remained mostly concealed within the subsurface for the past ∼3.5 Gyr. Localized rupturing of the permafrost-capped crust led to voluminous groundwater discharges that carved some of the largest known channels in the solar system. However, our knowledge of the nature of the flows and their ultimate fate remains incomplete, partly because diagnostic landforms at outflow channel termini have been largely destroyed or buried. The Hebrus Valles outflow channels were excavated by fluid discharges that emanated from two point sources, and they mostly terminate in systems of fractures and depressions within the northern plains. Our investigation indicates that outflow channel floodwaters were captured and reabsorbed into the subsurface in zones where caverns developed within the northern plains. These findings imply that the study region comprises the only known location in the Martian northern lowlands where the fate of outflow channel discharges can be assessed with confidence. We propose that evacuation of subsurface materials via mud volcanism was an important process in cavern formation. Our conceptual model provides a hypothesis to account for the fate of sediments and fluids from some of the Martian outflow channels. It also reveals a mechanism for lowland cavern formation and upper crustal volatile enrichment after the development of the Martian global cryosphere.

  11. Martian Radiative Transfer Modeling Using the Optimal Spectral Sampling Method

    Science.gov (United States)

    Eluszkiewicz, J.; Cady-Pereira, K.; Uymin, G.; Moncet, J.-L.

    2005-01-01

    The large volume of existing and planned infrared observations of Mars have prompted the development of a new martian radiative transfer model that could be used in the retrievals of atmospheric and surface properties. The model is based on the Optimal Spectral Sampling (OSS) method [1]. The method is a fast and accurate monochromatic technique applicable to a wide range of remote sensing platforms (from microwave to UV) and was originally developed for the real-time processing of infrared and microwave data acquired by instruments aboard the satellites forming part of the next-generation global weather satellite system NPOESS (National Polarorbiting Operational Satellite System) [2]. As part of our on-going research related to the radiative properties of the martian polar caps, we have begun the development of a martian OSS model with the goal of using it to perform self-consistent atmospheric corrections necessary to retrieve caps emissivity from the Thermal Emission Spectrometer (TES) spectra. While the caps will provide the initial focus area for applying the new model, it is hoped that the model will be of interest to the wider Mars remote sensing community.

  12. Survivability and growth kinetics of methanogenic archaea at various pHs and pressures: Implications for deep subsurface life on Mars

    Science.gov (United States)

    Sinha, Navita; Nepal, Sudip; Kral, Timothy; Kumar, Pradeep

    2017-02-01

    Life as we know it requires liquid water and sufficient liquid water is highly unlikely on the surface of present-day Mars. However, according to thermal models there is a possibility of liquid water in the deep subsurface of Mars. Thus, the martian subsurface, where the pressure and temperature is higher, could potentially provide a hospitable environment for a biosphere. Also, methane has been detected in the Mars' atmosphere. Analogous to Earth's atmospheric methane, martian methane could also be biological in origin. The carbon and energy sources for methanogenesis in the subsurface of Mars could be available by downwelling of atmospheric CO2 into the regolith and water-rock reactions such as serpentinization, respectively. Corresponding analogs of the martian subsurface on Earth might be the active sites of serpentinization at depths where methanogenic thermophilic archaea are the dominant species. Methanogens residing in Earth's hydrothermal environments are usually exposed to a variety of physiological stresses including a wide range of pressures, temperatures, and pHs. Martian geochemical models imply that the pH of probable groundwater varies from 4.96 to 9.13. In this work, we used the thermophilic methanogen, Methanothermobacter wolfeii, which grows optimally at 55oC. Therefore, a temperature of 55oC was chosen for these experiments, possibly simulating Mars' subsurface temperature. A martian geophysical model suggests depth and pressure corresponding to a temperature of 55 °C would be between 1-30 km and 100-3,000 atm respectively. Here, we have simulated Mars deep subsurface pH, pressure, and temperature conditions and have investigated the survivability, growth rate, and morphology of M. wolfeii after exposure to a wide range of pH 5-9) and pressure (1-1200 atm) at a temperature of 55 °C. Interestingly, in this study we have found that M. wolfeii was able to survive at all the pressures and pHs tested at 55 °C. In order to understand the effect of

  13. Survival and growth of Salmonella enterica serovar enteritidis in membrane-processed liquid egg white with pH, temperature, and storage conditions as controlling factors.

    Science.gov (United States)

    Mukhopadhyay, Sudarsan; Ukuku, Dike; Phillips, John G; Juneja, Vijay K

    2012-07-01

    Processing temperature and pH are known to influence the lethality and cell injury in many microbial interventions. A study was undertaken to determine the effects of variations in solution pH and process temperature on the removal and growth of Salmonella enterica serovar Enteritidis in liquid egg white (LEW) by microfiltration (MF) membrane process. The effects of various storage conditions on the growth of Salmonella in membrane-separated LEW were evaluated. Pretreated and pH-adjusted (pH 6 to pH 9) LEW was inoculated with a five-strain composite of S. enterica serovar Enteritidis at ca. 7 log CFU/ml, microfiltered at 25 or 40°C, and stored at 4 or 10°C. Temperature had a greater influence on Salmonella reduction than did pH. The maximum reduction of Salmonella and background microflora in LEW by MF was observed at 40°C and pH 8 and 9. However, the influence of temperature on permeate flow was less than that of pH. The mean permeate flow increased by 180% at 25°C as the pH decreased from 9 to 6, while flow increased merely by 18% at pH 6 as temperature increased from 25 to 40°C. Salmonella populations in processed LEW at 4°C storage remained quite stable (0.01 to 0.55 log CFU/ml), irrespective of MF experimental conditions. At 10°C the population was greater, but no major outgrowth was observed. Findings from this study would be advantageous to liquid egg processing industries.

  14. Impact of feed restriction and housing hygiene conditions on specific and inflammatory immune response, the cecal bacterial community and the survival of young rabbits.

    Science.gov (United States)

    Combes, S; Massip, K; Martin, O; Furbeyre, H; Cauquil, L; Pascal, G; Bouchez, O; Le Floc'h, N; Zemb, O; Oswald, I P; Gidenne, T

    2017-05-01

    Limiting the post-weaning intake of the young rabbit is known to improve its resistance to digestive disorders, whereas a degradation of its housing hygiene is assumed to have a negative impact on its health. This study aims at providing insights into the mechanism of digestive health preservation regarding both host (growth and immune response) and its symbiotic digestive microbiota. A 2×2 factorial design from weaning (day 28) to day 64 was set up: ad libitum intake or restricted intake at 70% of ad libitum, and high v. low hygiene of housing (n=105 per group). At day 36 and day 45, 15 animals/group were subcutaneously immunized with ovalbumin (OVA) to assess their specific immune response. Blood was sampled at 36, 45, 57 and 64 days of age to determine total and anti-OVA immunoglobulin type G (IgG) and haptoglobin levels. The cecal bacterial community was explored (18 per group) by 454 pyrosequencing of genes coding for the 16S ribosomal RNA, whereas cecal pH, NH3 and volatile fatty acid (VFA) concentrations were measured to characterize fermentative activity. A 30% reduction in feed intake reduced the growth by only 17% (PPPPP=0.047), whereas degraded hygiene conditions decreased overall morbidity (7.8% v. 16.6%; PPv. 2.4; PPPP<0.05). In conclusion, the degradation of hygiene conditions failed to induce a systematic specific and inflammatory response in rabbit, but reduced morbidity instead. Our results suggest that the microbiota composition would be a helpful source of biomarkers of digestive health.

  15. Experimental Evidence for Weathering and Martian Sulfate Formation Under Extremely Cold Weather-Limited Environments

    Science.gov (United States)

    Niles, Paul B.; Golden, D. C.; Michalski, J.

    2013-01-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one of the most important discoveries being wide-spread layered sedimentary deposits associated with sulfate minerals across the low to mid latitude regions of Mars [1, 2]. The mechanism for sulfate formation on Mars has been frequently attributed to playa-like evaporative environments under prolonged warm conditions [3]. However, there are several problems with the presence of prolonged surface temperatures on Mars above 273 K during the Noachian including the faint young Sun [4] and the presence of suitable greenhouse gases [5]. The geomorphic evidence for early warm conditions may instead be explained by periodic episodes of warming rather than long term prolonged warm temperatures [6]. An alternate view of the ancient martian climate contends that prolonged warm temperatures were never present and that the atmosphere and climate has been similar to modern conditions throughout most of its history [6]. This view is more consistent with the climate models, but has had a difficult time explaining the sedimentary history of Mars and in particular the presence of sulfate minerals. We suggest here that mixtures of atmospheric aerosols, ice, and dust have the potential for creating small films of cryo-concentrated acidic solutions that may represent an important unexamined environment for understanding weathering processes on Mars [7, 8]. This study seeks to test whether sulfate formation may be possible at temperatures well below 0 C in water limited environments removing the need for prolonged warm periods to form sulfates on early Mars.

  16. Martian fluvial conglomerates at Gale Crater

    Science.gov (United States)

    Williams, Rebecca M.E.; Grotzinger, J.P.; Dietrich, W.E.; Gupta, S.; Sumner, D.Y.; Wiens, R.C.; Mangold, N.; Malin, M.C.; Edgett, K.S.; Maurice, S.; Forni, O.; Gasnault, O.; Ollila, A.; Newsom, Horton E.; Dromart, G.; Palucis, M.C.; Yingst, R.A.; Anderson, Ryan B.; Herkenhoff, K. E.; Le Mouélic, S.; Goetz, W.; Madsen, M.B.; Koefoed, A.; Jensen, J.K.; Bridges, J.C.; Schwenzer, S.P.; Lewis, K.W.; Stack, K.M.; Rubin, D.; Kah, L.C.; Bell, J.F.; Farmer, J.D.; Sullivan, R.; Van Beek, T.; Blaney, D.L.; Pariser, O.; Deen, R.G.

    2013-01-01

    Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.

  17. Effect of Lemongrass Essential Oil Vapors on Microbial Dynamics and Listeria monocytogenes Survival on Rocket and Melon Stored under Different Packaging Conditions and Temperatures

    Directory of Open Access Journals (Sweden)

    Agni Hadjilouka

    2015-09-01

    Full Text Available The aim of the present study was to examine the effect of lemongrass essential oil vapors on the dynamics of surface microbiota and L. monocytogenes growth on rocket and melon under different packaging conditions and storage temperature. For that purpose, rocket and melon were placed on Expanded Polystyrene (EPS trays, sprayed with L. monocytogenes to a population of 4.5–5.0 log CFU·g−1, packaged using microperforated Oriented Polypropylene (OPP film in either air or Microperforated Active Modified Atmosphere (MAMA (initial atmosphere 5% O2, 10% CO2 including a Whatman paper containing the essential oil, without contact with the product, and stored at 0, 5, 10, and 15 °C. Application of lemongrass exhibited a bactericidal effect on enterococci and a fungistatic effect on yeast-mould populations but only during air storage of rocket. The former took place at all temperatures and the latter only at 10 and 15 °C. No effect on shelf life of both products was recorded. However, an important effect on the sensorial properties was observed; during the first 4–5 days of storage both products were organoleptically unacceptable. Regarding MAMA packaging, it affected only Pseudomonas spp. population resulting in a reduction of 1–2 log CFU·g−1 in both products.

  18. Exendin-4 Promotes Survival of Mouse Pancreatic β-Cell Line in Lipotoxic Conditions, through the Extracellular Signal-Related Kinase 1/2 Pathway

    Directory of Open Access Journals (Sweden)

    Jianqiu Gu

    2016-01-01

    Full Text Available Type 2 diabetes is a heterogeneous disorder that develops as a result of relatively inappropriate insulin secretion and insulin resistance. Increased levels of free fatty acids (FFAs are one of the important factors for the pathogenesis of type 2 diabetes and contribute to defective β-cell proliferation and increased β-cell apoptosis. Recently, glucagon-like peptide-1 (GLP-1 receptor agonists have been shown to possess an antiapoptotic effect, by increasing β-cell mass and improving β-cell function. However, their effects on β-cells in vitro against lipotoxicity have not been elucidated completely. In this study, we investigated whether the GLP-1 receptor agonist exendin-4 displays prosurvival effects in pancreatic β-cells exposed to chronic elevated FFAs. Results showed that exendin-4 inhibited apoptosis induced by palmitate in MIN6 cells. After 24 h of incubation, exendin-4 caused rapid activation of extracellular signal-related kinase 1/2 (ERK1/2 under lipotoxic conditions. The ERK1/2 inhibitor PD98059 blocked the antilipotoxic effect of exendin-4 on MIN6 cells. Exendin-4 also inhibited the mitochondrial pathway of apoptosis. This inhibition is associated with upregulation of BCL-2. Our findings suggested that exendin-4 may exert cytoprotective effects through activation of ERK1/2 and inhibition of the mitochondrial apoptosis pathway.

  19. Effect of Lemongrass Essential Oil Vapors on Microbial Dynamics and Listeria monocytogenes Survival on Rocket and Melon Stored under Different Packaging Conditions and Temperatures

    Science.gov (United States)

    Hadjilouka, Agni; Polychronopoulou, Melissanthi; Paramithiotis, Spiros; Tzamalis, Periklis; Drosinos, Eleftherios H.

    2015-01-01

    The aim of the present study was to examine the effect of lemongrass essential oil vapors on the dynamics of surface microbiota and L. monocytogenes growth on rocket and melon under different packaging conditions and storage temperature. For that purpose, rocket and melon were placed on Expanded Polystyrene (EPS) trays, sprayed with L. monocytogenes to a population of 4.5–5.0 log CFU·g−1, packaged using microperforated Oriented Polypropylene (OPP) film in either air or Microperforated Active Modified Atmosphere (MAMA) (initial atmosphere 5% O2, 10% CO2) including a Whatman paper containing the essential oil, without contact with the product, and stored at 0, 5, 10, and 15 °C. Application of lemongrass exhibited a bactericidal effect on enterococci and a fungistatic effect on yeast-mould populations but only during air storage of rocket. The former took place at all temperatures and the latter only at 10 and 15 °C. No effect on shelf life of both products was recorded. However, an important effect on the sensorial properties was observed; during the first 4–5 days of storage both products were organoleptically unacceptable. Regarding MAMA packaging, it affected only Pseudomonas spp. population resulting in a reduction of 1–2 log CFU·g−1 in both products. PMID:27682104

  20. Biohazard potential of putative Martian organisms during missions to Mars.

    Science.gov (United States)

    Warmflash, David; Larios-Sanz, Maia; Jones, Jeffrey; Fox, George E; McKay, David S

    2007-04-01

    Exploration Class missions to Mars will require precautions against potential contamination by any native microorganisms that may be incidentally pathogenic to humans. While the results of NASA's Viking biology experiments of the 1970s have been generally interpreted as inconclusive for surface organisms, and attributed to active but nonbiological chemistries, the possibility of native surface life has never been ruled out completely. It is possible that, prior to the first human landing on Mars, robotic craft and sample return missions will provide enough data to know with certainty whether future human landing sites harbor extant life forms. If native life were found to exist, it would be problematic to determine whether any of its species might present a medical danger to astronauts. Therefore, it will become necessary to assess empirically the risk that the planet contains pathogens based on terrestrial examples of pathogenicity and to take a reasonably cautious approach to biohazard protection. A survey of terrestrial pathogens was conducted with special emphasis on those whose evolution has not depended on the presence of animal hosts. The history of the development and implementation of Apollo anti-contamination protocol and recommendations of the National Research Council's Space Studies Board regarding Mars were reviewed. Organisms can emerge in Nature in the absence of indigenous animal hosts and both infectious and non-infectious human pathogens are therefore theoretically possible on Mars. Although remote, the prospect of Martian surface life, together with the existence of a diversity of routes by which pathogenicity has emerged on Earth, suggests that the probability of human pathogens on Mars, while low, is not zero. Still, since the discovery and study of Martian life can have long-term benefits for humanity, the risk that Martian life might include pathogens should not be an obstacle to human exploration. As a precaution, it is recommended that EVA

  1. Innovations’ Survival

    Directory of Open Access Journals (Sweden)

    Jakub Tabas

    2016-01-01

    Full Text Available Innovations currently represent a tool of maintaining the going concern of a business entity and its competitiveness. However, effects of innovations are not infinite and if an innovation should constantly preserve a life of business entity, it has to be a continual chain of innovations, i.e. continual process. Effective live of a single innovation is limited while the limitation is derived especially from industry. The paper provides the results of research on innovations effects in the financial performance of small and medium-sized enterprises in the Czech Republic. Objective of this paper is to determine the length and intensity of the effects of technical innovations in company’s financial performance. The economic effect of innovations has been measured at application of company’s gross production power while the Deviation Analysis has been applied for three years’ time series. Subsequently the Survival Analysis has been applied. The analyses are elaborated for three statistical samples of SMEs constructed in accordance to the industry. The results obtained show significant differences in innovations’ survival within these three samples of enterprises then. The results are quite specific for the industries, and are confronted and discussed with the results of authors’ former research on the issue.

  2. Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric CO2 by the Phoenix Lander

    Science.gov (United States)

    Niles, Paul B.; Boynton, W. V.; Hoffman, J. H.; Ming, D. W.; Hamara, D.

    2010-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars [1]. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (<1%) has yet to be achieved. Given the elevated Delta(sup 13)C values measured in carbonates in martian meteorites [2-4] it has been proposed that the martian atmosphere was enriched in 13C [8]. This was supported by measurements of trapped CO2 gas in EETA 79001[2] which showed elevated Delta(sup 13)C values (Table 1). More recently, Earth-based spectroscopic measurements of the martian atmosphere have measured the martian CO2 to be depleted in C-13 relative to CO2 in the terrestrial atmosphere[ 7, 9-11]. The Thermal and Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander [12] included a magnetic-sector mass spectrometer (EGA) [13] which had the goal of measuring the isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils.

  3. Fractionated Noble Gases in Martian Meteorite ALH 84001 — An Indicator for Water-Rock Interaction, or a Sample of Ancient Atmosphere?

    Science.gov (United States)

    Schwenzer, S. P.; Bart, G.; Bridges, J. C.; Crowther, S. A.; Filiberto, J.; Gilmour, J. D.; Herrmann, S.; Hicks, L. J.; Kelley, S. P.; Miller, M. A.; Ott, U.; Steer, E. D.; Swindle, T. D.; Treiman, A. H.

    2017-10-01

    Noble gases in the nakhlite and ALH84001 Martian meteorites are still a mystery, but could tell us about either the history of the Martian atmosphere, Martian water rock interaction or - likely - both!

  4. Preparing for InSight: An Invitation to Participate in a Blind Test for Martian Seismicity

    Science.gov (United States)

    Clinton, J. F.

    2017-07-01

    The InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) lander will deploy a seismic monitoring package on Mars in November 2018. In preparation for the data return, we prepared a blind test in which we invite participants to detect and characterize seismicity included in a synthetic dataset of continuous waveforms from a single station that mimics both the streams of data that will be available from InSight, as well as expected tectonic and impact seismicity and noise conditions on Mars. We expect that the test will ultimately improve and extend the current set of methods that the InSight team plan to use in routine analysis of the Martian dataset.

  5. They're Alive! Present-Day Evolution of Martian Dunes

    Science.gov (United States)

    Diniega, S.; Bridges, N.; Hansen, C.

    2011-01-01

    The sharp brinks and margins, smooth and steep lee slopes, and lack of superimposed landforms (such as small impact craters) on many Martian sand dunes suggests that these features are geologically young clean brinks and smooth/steep lee slopes (HiRISE image PSP_010413_1920; 20 deg N,79 deg E; image widthis about 500m).Within the last decade, and often primarily through the detailed inspection of high-resolution (HiRISE) images, we have finally found clear evidence that many dunes of Mars are active -- through both aeolian and seasonal (frost) processes. However, it is yet unclear if active dune formation does occur or if we are observing surficial modification of dunes which formed under different climate conditions.

  6. (U-Th)/He ages of phosphates from Zagami and ALHA77005 Martian meteorites: Implications to shock temperatures

    Science.gov (United States)

    Min, Kyoungwon; Farah, Annette E.; Lee, Seung Ryeol; Lee, Jong Ik

    2017-01-01

    Shock conditions of Martian meteorites provide crucial information about ejection dynamics and original features of the Martian rocks. To better constrain equilibrium shock temperatures (Tequi-shock) of Martian meteorites, we investigated (U-Th)/He systematics of moderately-shocked (Zagami) and intensively shocked (ALHA77005) Martian meteorites. Multiple phosphate aggregates from Zagami and ALHA77005 yielded overall (U-Th)/He ages 92.2 ± 4.4 Ma (2σ) and 8.4 ± 1.2 Ma, respectively. These ages correspond to fractional losses of 0.49 ± 0.03 (Zagami) and 0.97 ± 0.01 (ALHA77005), assuming that the ejection-related shock event at ∼3 Ma is solely responsible for diffusive helium loss since crystallization. For He diffusion modeling, the diffusion domain radius is estimated based on detailed examination of fracture patterns in phosphates using a scanning electron microscope. For Zagami, the diffusion domain radius is estimated to be ∼2-9 μm, which is generally consistent with calculations from isothermal heating experiments (1-4 μm). For ALHA77005, the diffusion domain radius of ∼4-20 μm is estimated. Using the newly constrained (U-Th)/He data, diffusion domain radii, and other previously estimated parameters, the conductive cooling models yield Tequi-shock estimates of 360-410 °C and 460-560 °C for Zagami and ALHA77005, respectively. According to the sensitivity test, the estimated Tequi-shock values are relatively robust to input parameters. The Tequi-shock estimates for Zagami are more robust than those for ALHA77005, primarily because Zagami yielded intermediate fHe value (0.49) compared to ALHA77005 (0.97). For less intensively shocked Zagami, the He diffusion-based Tequi-shock estimates (this study) are significantly higher than expected from previously reported Tpost-shock values. For intensively shocked ALHA77005, the two independent approaches yielded generally consistent results. Using two other examples of previously studied Martian meteorites

  7. Constraining Hesperian martian PCO2 from mineral analysis at Gale crater

    Science.gov (United States)

    Bristow, T.; Haberle, R. M.; Blake, D. F.; Vaniman, D. T.; Grotzinger, J. P.; Siebach, K. L.; Des Marais, D. J.; Rampe, E. B.; Eigenbrode, J. L.; Sutter, B.; Fairén, A. G.; Mischna, M.; Vasavada, A. R.

    2016-12-01

    Carbon dioxide is an essential atmospheric component in martian climate models that attempt to reconcile a faint young sun with widespread evidence of liquid water at the planet's surface in the Noachian and Early Hesperian. Current estimates of ancient martian CO2 levels, derived from global inventories of carbon, and orbital detections of Noachian and Early Hesperian clay mineral-bearing terrains indicate CO2 levels that are unable to support warm and wet conditions. These estimates are subject to various sources of uncertainty however. Mineral and contextual sedimentary environmental data collected by the Mars Science Laboratory rover Curiosity in Gale Crater provide a more direct means of estimating the atmospheric partial pressure of CO2 (PCO2) coinciding with a long-lived lake system in Gale crater at 3.5 Ga. Results from a reaction-transport model, which simulates mineralogy observed within the Sheepbed member at Yellowknife Bay by coupling mineral equilibria with carbonate precipitation kinetics and rates of sedimentation, indicate atmospheric levels in the 10's mbar range. At such low PCO2 levels, climate models are unable to warm Hesperian Mars anywhere near the freezing point of water and other gases are required to raise atmospheric pressure to prevent lakes from boiling away. Thus, lacustrine features of Gale formed in a cold environment by a mechanism yet to be determined, or the climate models lack an essential component that would serve to elevate surface temperatures, at least temporally and/or locally, on Hesperian Mars. Our results also impose restrictions on the potential role of atmospheric CO2 in inferred warmer conditions of the Noachian.

  8. P21C-2113: Constraining Hesperian Martian PCO2 from Mineral Analysis at Gale Crater

    Science.gov (United States)

    Bristow, Thomas; Haberle, Robert Michael; Blake, David Frederick; Vaniman, David T.; Grotzinger, John P.; Siebach, Kirsten L.; Des Marais, David J.; Rampe, Elizabeth B.; Eigenbrode, Jennifer L.; Sutter, Brad; hide

    2016-01-01

    Carbon dioxide is an essential atmospheric component in martian climate models that attempt to reconcile a faint young sun with widespread evidence of liquid water at the planet's surface in the Noachian and Early Hesperian. Current estimates of ancient martian CO levels, derived from global inventories of carbon, and orbital detections of Noachian and Early Hesperian clay mineralbearing terrains indicate CO levels that are unable to support warm and wet conditions. These estimates are subject to various sources of uncertainty however. Mineral and contextual sedimentary environmental data collected by the Mars Science Laboratory rover Curiosity in Gale Crater provide a more direct means of estimating the atmospheric partial pressure of CO (P ) coinciding with a long-lived lake system in Gale crater at approximately 3.5 Ga. Results from a reaction transport model, which simulates mineralogy observed within the Sheepbed member at Yellowknife Bay by coupling mineral equilibria with carbonate precipitation kinetics and rates of sedimentation, indicate atmospheric levels in the 10's mbar range. At such low P levels, climate models are unable to warm Hesperian Mars anywhere near the freezing point of water and other gases are required to raise atmospheric pressure to prevent lakes from boiling away. Thus, lacustrine features of Gale formed in a cold environment by a mechanism yet to be determined, or the climate models lack an essential component that would serve to elevate surface temperatures, at least temporally and/or locally, on Hesperian Mars. Our results also impose restrictions on the potential role of atmospheric CO in inferred warmer conditions of the Noachian.

  9. Changes in thermo-tolerance and survival under simulated gastrointestinal conditions of Salmonella Enteritidis PT4 and Salmonella Typhimurium PT4 in chicken breast meat after exposure to sequential stresses.

    Science.gov (United States)

    Melo, Adma Nadja Ferreira de; Souza, Geany Targino de; Schaffner, Donald; Oliveira, Tereza C Moreira de; Maciel, Janeeyre Ferreira; Souza, Evandro Leite de; Magnani, Marciane

    2017-06-19

    This study assessed changes in thermo-tolerance and capability to survive to simulated gastrointestinal conditions of Salmonella Enteritidis PT4 and Salmonella Typhimurium PT4 inoculated in chicken breast meat following exposure to stresses (cold, acid and osmotic) commonly imposed during food processing. The effects of the stress imposed by exposure to oregano (Origanum vulgare L.) essential oil (OVEO) on thermo-tolerance were also assessed. After exposure to cold stress (5°C for 5h) in chicken breast meat the test strains were sequentially exposed to the different stressing substances (lactic acid, NaCl or OVEO) at sub-lethal amounts, which were defined considering previously determined minimum inhibitory concentrations, and finally to thermal treatment (55°C for 30min). Resistant cells from distinct sequential treatments were exposed to simulated gastrointestinal conditions. The exposure to cold stress did not result in increased tolerance to acid stress (lactic acid: 5 and 2.5μL/g) for both strains. Cells of S. Typhimurium PT4 and S. Enteritidis PT4 previously exposed to acid stress showed higher (psurvived the sequential stress exposure (resistant) showed higher tolerance (psurvival rates (psurvival under gastrointestinal conditions of S. Enteritidis PT4 and S. Typhimurium PT4. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Constraints on the Martian cratering rate imposed by the SNC meteorites and Vallis Marineris layered deposits

    Science.gov (United States)

    Brandenburg, J. E.

    1993-01-01

    Following two independent lines of evidence -- estimates of the age and formation time of a portion of the Martian geologic column exposed in the layered deposits and the crystallization and ejection ages of the SNC meteorites -- it appears that the Martian cratering rate must be double the lunar rate or even higher. This means models such as NHII or NHIII (Neukum and Hiller models II and III), which estimate the Martian cratering rate as being several times lunar are probably far closer to reality on Mars than lunar rates. The effect of such a shift is profound: Mars is transformed from a rather Moon-like place into a planet with vigorous dynamics, multiple large impacts, erosion, floods, and volcanism throughout its history. A strong shift upward in cratering rates on Mars apparently solves some glaring problems; however, it creates others. The period of time during which Earth-like atmospheric conditions existed, the liquid water era on Mars, persists in NHIII up to only 0.5 b.y. ago. Scenarios of extended Earth-like conditions on Mars have been discounted in the past because they would have removed many of the craters from the early bombardment era found in the south. It does appear that some process of crater removal was quite vigorous in the north during Mars' past. Evidence exists that the northern plains may have been the home of long-lived seas or perhaps even a paleo-ocean, so models exist for highly localized destruction of craters in the north. However, the question of how the ancient crater population could be preserved in the south under a long liquid-water era found in any high-cratering-rate models is a serious question that must be addressed. It does appear to be a higher-order problem because it involves low-energy dynamics acting in localized areas, i.e., erosion of craters in the south of Mars, whereas the two problems with the low-cratering-rate models involve high-energy events acting over large areas: the formation of the Vallis Marineris

  11. Whole-Body Exposure to (28)Si-Radiation Dose-Dependently Disrupts Dentate Gyrus Neurogenesis and Proliferation in the Short Term and New Neuron Survival and Contextual Fear Conditioning in the Long Term.

    Science.gov (United States)

    Whoolery, Cody W; Walker, Angela K; Richardson, Devon R; Lucero, Melanie J; Reynolds, Ryan P; Beddow, David H; Clark, K Lyles; Shih, Hung-Ying; LeBlanc, Junie A; Cole, Mara G; Amaral, Wellington Z; Mukherjee, Shibani; Zhang, Shichuan; Ahn, Francisca; Bulin, Sarah E; DeCarolis, Nathan A; Rivera, Phillip D; Chen, Benjamin P C; Yun, Sanghee; Eisch, Amelia J

    2017-11-01

    neurogenesis indices in male and female mice, although only male mice showed fewer surviving BrdU(+) cells in the long-term group. Fluorescent immunolabeling and confocal phenotypic analysis revealed that most surviving BrdU(+) cells in the long-term group expressed the neuronal marker NeuN, definitively confirming that exposure to 1 Gy (28)Si radiation decreased the number of surviving adult-generated neurons in male mice relative to both 0- and 0.2-Gy-irradiated mice. For hippocampal function assessment, 9-week-old male C57BL/6J mice received whole-body (28)Si-particle exposure and were then assessed long-term for performance on contextual and cued fear conditioning. In the context test the animals that received 0.2 Gy froze less relative to control animals, suggesting decreased hippocampal-dependent function. However, in the cued fear conditioning test, animals that received 1 Gy froze more during the pretone portion of the test, relative to controls and 0.2-Gy-irradiated mice, suggesting enhanced anxiety. Compared to previously reported studies, these data suggest that (28)Si-radiation exposure damages neurogenesis, but to a lesser extent than (56)Fe radiation and that low-dose (28)Si exposure induces abnormalities in hippocampal function, disrupting fear memory but also inducing anxiety-like behavior. Furthermore, exposure to (28)Si radiation decreased new neuron survival in long-term male groups but not females suggests that sex may be an important factor when performing brain health risk assessment for astronauts traveling in space.

  12. Agrobacterium tumefaciens Zur Regulates the High-Affinity Zinc Uptake System TroCBA and the Putative Metal Chaperone YciC, along with ZinT and ZnuABC, for Survival under Zinc-Limiting Conditions.

    Science.gov (United States)

    Chaoprasid, Paweena; Dokpikul, Thanittra; Johnrod, Jaruwan; Sirirakphaisarn, Sirin; Nookabkaew, Sumontha; Sukchawalit, Rojana; Mongkolsuk, Skorn

    2016-06-15

    Agrobacterium tumefaciens has a cluster of genes (Atu3178, Atu3179, and Atu3180) encoding an ABC-type transporter, here named troA, troB, and troC, respectively, which is shown here to be a zinc-specific uptake system. Reverse transcription (RT)-PCR analysis confirmed that troA, troB, and troC are cotranscribed, with troC as the first gene of the operon. The yciC (Atu3181) gene is transcribed in the opposite orientation to that of the troCBA operon and belongs to a metal-binding GTPase family. Expression of troCBA and yciC was inducible under zinc-limiting conditions and was controlled by the zinc uptake regulator, Zur. Compared to the wild type, the mutant strain lacking troC was hypersensitive to a metal chelator, EDTA, and the phenotype could be rescued by the addition of zinc, while the strain with a single yciC mutation showed no phenotype. However, yciC was important for survival under zinc limitation when either troC or zinT was inactivated. The periplasmic zinc-binding protein, ZinT, could not function when TroC was inactivated, suggesting that ZinT may interact with TroCBA in zinc uptake. Unlike many other bacteria, the ABC-type transporter ZnuABC was not the major zinc uptake system in A. tumefaciens However, the important role of A. tumefaciens ZnuABC was revealed when TroCBA was impaired. The strain containing double mutations in the znuA and troC genes exhibited a growth defect in minimal medium. A. tumefaciens requires cooperation of zinc uptake systems and zinc chaperones, including TroCBA, ZnuABC, ZinT, and YciC, for survival under a wide range of zinc-limiting conditions. Both host and pathogen battle over access to essential metals, including zinc. In low-zinc environments, physiological responses that make it possible to acquire enough zinc are important for bacterial survival and could determine the outcome of host-pathogen interactions. A. tumefaciens was found to operate a novel pathway for zinc uptake in which ZinT functions in concert with

  13. Astrobiological Significance of Definitive Mineralogical Analysis of Martian Surface Samples Using the CheMin XRD/XRF Instrument

    Science.gov (United States)

    Feldman, S. M.; Blake, D. F.; Sarrazin, P.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Collins, S.

    2004-01-01

    The search for evidence of habitability, or of extant or extinct life on Mars, will initially be a search for evidence of past or present conditions supportive of life. The three key requirements for the emergence of life are thought to be liquid water; a suitable energy source; and chemical building blocks. CheMin is a miniaturized XRD/XRF (X-Ray diffraction / X-ray fluorescence) instrument which has been developed for definitive mineralogic analysis of soils and rocks on the Martian surface. The CheMin instrument can provide information that is highly relevant to each of these habitability requirements as summarized below.

  14. Remote sensing of impact crater-exposed subsurface lithologies and Martian rayed crater systems

    Science.gov (United States)

    Tornabene, Livio Leonardo

    Impact cratering is ubiquitous, energetic and fundamental geologic process acting on the solid planetary bodies. As a consequence, craters provide planetary scientists with useful information regarding the surface and subsurface properties of planetary bodies. Specific mineral and lithologic compositions can be ascertained via craters in two ways: (1) by the remote sensing of crater-exposed subsurface materials, or (2) by studying the differentiated meteorites (e.g., lunar, Martian, etc.) ejected from their surfaces by high-energy impacts under specific conditions. As a proof of concept for subsurface-crater mapping, remote sensing techniques were applied to a terrestrial impact structure. Visible-near infrared (VNIR), short- wavelength infrared (SWIR), and thermal infrared (TIR) data were used to map the subsurface geology of a portion of Devon Island (High Canadian Arctic) via the impact-exposed subsurface lithologies of the 23-kilometer diameter Haughton impact structure. The results from the "blind" remote sensing of Haughton suggest that the spectral and lithologic mapping techniques used in this study can also be used to understand subsurface geology of Mars. TIR images from Thermal Emission Imaging System (THEMIS) onboard Mars Odyssey were used in a similar fashion to spectrally map craters within the Isidis basin on Mars. Complementary hyperspectral information from the Thermal Emission Spectrometer (TES) allowed mineral and litho-type compositional determinations, albeit at a much lower spatial resolution. An olivine-rich basaltic unit mapped at the surface and was linked with a subsurface occurrence via exposure from impact craters occurring within the basin. These two studies (Chapters 2 and 3) demonstrate that, in conjunction with surface mapping, impact craters provide a natural "window" for understanding the stratigraphy and petrogenesis of planetary crusts. In another project presented here (Chapter 4), rayed crater systems on Mars, which are

  15. REMS Ultraviolet Sensor: First UV measurements from the Martian surface.

    Science.gov (United States)

    Zorzano, María-Paz; Martín-Torres, Francisco Javier; Navarro-Gonzalez, Rafael; Martín-Soler, Javier; Javier Gómez-Elvira, REMS Team; the MSL Science Team

    2013-04-01

    From its arrival to the Martian surface on August 2012, the REMS-UVS (Ultra Violet Sensor) has monitored, daily, the down-welling UV irradiance. These are the first UV irradiance measurements ever acquired from the surface of another planet. The UVS consists of one SiC photodiode dedicated to the full UV spectrum 200-400 nm together with 5 filtered photodiodes for narrower band channels. It has a physical aperture of 30° pointing to the sky. When the solar zenith angle of the Sun is beyond this angle, the sensor monitors only the diffuse irradiance of the sky. Furthermore during the daily usual rover operation it can also be protected from the direct irradiance by shadows casted by the rover mast or arm, allowing for a continuous independent monitoring of the direct and diffuse components of the global UV surface irradiance. The measurements delivered from Gale crater, the landing site of the Mars Science Laboratory (MSL) Rover Curiosity, right after the beginning of operations provide an upper limit to the incident UV irradiance because: i) Gale is almost in the Equator; ii) the Sun-Mars distance was minimal; and (ii) the sky was clear of dust aerosols. These measurements are critical values for the estimates of UV doses on the Martian surface with relevant implications for habitability, and atmospheric and surface photo-chemistry modelling. With the onset of the dust season, and as the total column of dust above Gale increases, the UVS measurements shows an expected depletion on the irradiance reaching the surface as the UV radiation is significantly blocked. The REMS-UVS will deliver all through its operational life daily, hourly, values of these quantities providing an unique dataset that will allow to study the interaction of the solar irradiance with the Martian atmosphere and surface and to monitor the dust cycle.

  16. Rocket dust storms and detached layers in the Martian atmosphere

    Science.gov (United States)

    Spiga, A.; Faure, J.; Madeleine, J.; Maattanen, A. E.; Forget, F.

    2012-12-01

    Airborne dust is the main climatic agent in the Martian environment. Local dust storms play a key role in the dust cycle; yet their life cycle is poorly known. Here we use mesoscale modeling with radiatively-active transported dust to predict the evolution of a local dust storm monitored by OMEGA onboard Mars Express. We show that the evolution of this dust storm is governed by deep convective motions. The supply of convective energy is provided by the absorption of incoming sunlight by dust particles, in lieu of latent heating in moist convection on Earth. We propose to use the terminology "rocket dust storm", or conio-cumulonimbus, to describe those storms in which rapid and efficient vertical transport takes place, injecting dust particles at high altitudes in the Martian troposphere (30 to 50 km). Combined to horizontal transport by large-scale winds, rocket dust storms form detached layers of dust reminiscent of those observed with instruments onboard Mars Global Surveyor and Mars Reconnaissance Orbiter. Detached layers are stable over several days owing to nighttime sedimentation being unable to counteract daytime convective transport, and to the resupply of convective energy at sunrise. The peak activity of rocket dust storms is expected in low-latitude regions at clear season, which accounts for the high-altitude tropical dust maximum unveiled by Mars Climate Sounder. Our findings on dust-driven deep convection have strong implications for the Martian dust cycle, thermal structure, atmospheric dynamics, cloud microphysics, chemistry, and robotic and human exploration.ensity-scaled dust optical depth at local times 1400 1600 and 1800 (lat 2.5°S, Ls 135°) hortwave heating rate at local time 1500 and latitude 2.5°S.

  17. "Martian Boneyards": Sustained Scientific Inquiry in a Social Digital Game

    Science.gov (United States)

    Asbell-Clarke, Jordis

    Social digital gaming is an explosive phenomenon where youth and adults are engaged in inquiry for the sake of fun. The complexity of learning evidenced in social digital games is attracting the attention of educators. Martian Boneyards is a proof-of-concept game designed to study how a community of voluntary gamers can be enticed to engage in sustained, high-quality scientific inquiry. Science educators and game designers worked together to create an educational game with the polish and intrigue of a professional-level game, striving to attract a new audience to scientific inquiry. Martian Boneyards took place in the high-definition, massively multiplayer online environment, Blue Mars, where players spent an average of 30 hours in the game over the 4-month implementation period, with some exceeding 200 hours. Most of the players' time was spent in scientific inquiry activities and about 30% of the players' in-game interactions were in the analysis and theory-building phases of inquiry. Female players conducted most of the inquiry, in particular analysis and theory building. The quality of scientific inquiry processes, which included extensive information gathering by players, and the resulting content were judged to be very good by a team of independent scientists. This research suggests that a compelling storyline, a highly aesthetic environment, and the emergent social bonds among players and between players and the characters played by designers were all responsible for sustaining high quality inquiry among gamers in this free-choice experience. The gaming environment developed for Martian Boneyards is seen as an evolving ecosystem with interactions among design, players' activity, and players' progress.

  18. Martian climate - An empirical test of possible gross variations

    Science.gov (United States)

    Owen, T.

    1974-01-01

    There appears to be evidence for a cyclic behavior of the Martian climate in which the surface pressure periodically reaches values compatible with the flow of water in equatorial regions on the planet. A relatively simple test of such hypotheses is pointed out. The premise on which cyclic models are based is that a substantial reservoir of volatils exist in frozen form at one or both poles. The proposed test involves a determination of the relative abundances of neon and argon isotopes. The required measurements may be made after the soft landing next February of Soviet spacecraft presently en route to the planet.

  19. Martian cave air-movement via Helmholtz resonance

    Directory of Open Access Journals (Sweden)

    Kaj E. Williams

    2017-09-01

    Full Text Available Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs on Tharsis, suggested as candidate cave entrance locations. The results show that, for several possible cave air movement periods, we are able to infer the approximate cave volumes. The utility of inferring cave volumes for planetary cave exploration is discussed.

  20. TDEM for Martian in situ resource prospecting missions

    Directory of Open Access Journals (Sweden)

    G. Tacconi

    2003-06-01

    Full Text Available This paper presents a TDEM (Time Domain Electromagnetic Methods application, addressed to the search for water on Mars. In this context, the opportunities for a TDEM system as payload in a future mission are investigated for different in situ exploration scenarios. The TDEM sounding capability is evaluated with respect to the expected Martian environment, and some considerations are made about the many unknown variables (above all the background EM noise and the subsoil composition altogether with the limited resources availability (mission constraints in mass, time and power and the way they could represent an obstacle for operations and measurements.

  1. An astrobiological study of high latitude martian analogue environments

    OpenAIRE

    Cousins, C.R.

    2010-01-01

    The search for life on Mars is in part reliant on the understanding of Martian environments, both past and present, in terms of what life may inhabit these environments, how this life may be preserved in the rock record, and how this rock record may be detected during future missions to Mars. In particular, the upcoming European Space Agency mission ‘ExoMars’ has the primary aim to identify evidence of past or present life on Mars, and the work presented here is carried out within this ...

  2. Photo-induced free radicals on a simulated Martian surface

    Science.gov (United States)

    Tseng, S.-S.; Chang, S.

    1974-01-01

    Results of an electron spin resonance study of free radicals in the ultraviolet irradiation of a simulated Martian surface suggest that the ultraviolet photolysis of CO or CO2, or a mixture of both, adsorbed on silica gel at minus 170 C involves the formation of OH radicals and possibly of H atoms as the primary process, followed by the formation of CO2H radicals. It is concluded that the photochemical synthesis of organic compounds could occur on Mars if the siliceous surface dust contains enough silanol groups and/or adsorbed H2O in the form of bound water.

  3. Martian cave air-movement via Helmholtz resonance

    Science.gov (United States)

    Williams, Kaj; Titus, Timothy N.; Okubo, Chris; Cushing, Glen

    2017-01-01

    Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs) on Tharsis, suggested as candidate cave entrance locations. The results show that, for several possible cave air movement periods, we are able to infer the approximate cave volumes. The utility of inferring cave volumes for planetary cave exploration is discussed.

  4. Gaussian-based filters for detecting Martian dust devils

    Science.gov (United States)

    Yang, F.; Mlsna, P.A.; Geissler, P.

    2006-01-01

    The ability to automatically detect dust devils in the Martian atmosphere from orbital imagery is becoming important both for scientific studies of the planet and for the planning of future robotic and manned missions. This paper describes our approach for the unsupervised detection of dust devils and the preliminary results achieved to date. The algorithm centers upon the use of a filter constructed from Gaussian profiles to match dust devil characteristics over a range of scale and orientation. The classification step is designed to reduce false positive errors caused by static surface features such as craters. A brief discussion of planned future work is included. ?? 2006 IEEE.

  5. Martian water: are there extant halobacteria on Mars?

    Science.gov (United States)

    Landis, G. A.

    2001-01-01

    On Earth, life exists in all niches where water exists in liquid form for at least a portion of the year. On Mars, any liquid water would have to be a highly concentrated brine solution. It is likely, therefore, that any present-day Martian microorganisms would be similar to terrestrial halophiles. Even if present-day life does not exist on Mars, it is an interesting speculation that ancient bacteria preserved in salt deposits could be retrieved from an era when the climate of Mars was more conducive to life.

  6. Martian Water: Are There Extant Halobacteria on Mars?

    OpenAIRE

    Landis, Geoffrey A.

    2001-01-01

    On Earth, life exists in all niches where water exists in liquid form for at least a portion of the year. On Mars, any liquid water would have to be a highly concentrated brine solution. It is likely, therefore, that any present-day Martian microorganisms would be similar to terrestrial halophiles. Even if present-day life is not present on Mars, it is an interesting speculation that ancient bacteria preserved in salt deposits could be retrieved from an era when the climate of Mars was mor...

  7. Summary of the Issues Regarding The Martian Subsurface Explorer

    Science.gov (United States)

    Eustes, A. W., III; Gertsch, L. S.; Lu, N.; Bridgford, E.; Tischler, A.; Stoner, M. S.; Wilcox, B. H.

    2000-01-01

    This is a summary of research work accomplished to date for the Jet Propulsion Laboratory by the Colorado School of Mines and the Michigan Technological University for the Martian Subsurface Explorer (SSX). The task involved a thorough review of the state of the art in drilling in the petroleum and mining industries in the following areas: 1) Drilling mechanics and energy requirements. 2) Sidewall friction in boreholes. 3) Rock property characteristics of basalt, permafrost, and ice. 4) Cuttings transport and recompaction of cuttings. and 5) Directional control at odd angle interfaces.

  8. Simulating hyperspectral images for Martian 3D scenes.

    Science.gov (United States)

    Douté, S.

    2017-09-01

    We present a tool for simulating hyperspectral images for 3D Martian scenes. Several lines of development are considered for achieving a high degree of realism : high resolution digital elevation models, description of material distribution with fractal characteristics, bidirectional reflectance measured in the laboratory as a function of geometry and wavelength for a series analogue materials, mixing of spectral signatures at different scales, 3D radiative transfer between atmosphere and surface. The simulator addresses two main needs (i) developing and testing methods for the correction of atmospheric and photometric effects images taken by orbiter around Mars (ii) developing and testing methods for the linear and nonlinear spectral unmixing applied to hyperspectral images.

  9. Implications of abundant hygroscopic minerals in the Martian regolith

    Science.gov (United States)

    Clark, B. C.

    1978-01-01

    Converging lines of evidence suggest that a significant portion of the Martian surface fines may consist of salts and smectite clays. Salts can form stoichiometric hydrates as well as eutectic solutions with depressed freezing points; clays contain bound water of constitution and adsorb significant quantities of water from the vapor phase. The formation of ice may be suppressed by these minerals in some regions on Mars, and their presence in abundance would imply important consequences for atmospheric and geologic processes and the prospects for exobiology.

  10. Solar-driven chemical energy source for a Martian biota

    Science.gov (United States)

    Clark, B. C.

    1979-01-01

    Microorganisms deep in the Martian soil could derive energy indirectly from the sun via chemical reactions involving atmospheric photolysis products of the solar ultraviolet flux. The Viking discovery of a chemically uniform regolith which, though poor in organics, is rich in sulfur-containing compounds suggests reaction sequences in which sulfur is recycled through reduced and oxidized states by biologically catalyzed reactions