Results 11 to 20 of about 8,069 (192)

Gas release in comet nuclei

The Astrophysical Journal, 1990
The evolution of a comet nucleus is investigated, taking into account the crystallization process by which the gas trapped in the ice is released to flow through the porous ice matrix. The equations of conservation of the energy and of the masses of ice and gas are solved throughout the nucleus, to obtain the evolution of the temperature, gas pressure
D, Prialnik, A, Bar-Nun
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Mid-infrared spectra of comet nuclei [PDF]

Icarus, 2017
Jovian Trojan D-type asteroids have mid-infrared emissivity features strikingly similar to comet comae, suggesting that they have the same compositions and that the surfaces of the Trojans are highly porous. However, a direct comparison between a comet and asteroid surface has not been possible due to the paucity of spectra of comet nuclei at mid ...
Michael S.P. Kelley, Charles E. Woodward, Robert D. Gehrz, William T. Reach, David E. Harker   +4 more
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Development of an automated scoring system for plant comet assay

Frontiers in Genetics, 2015
In plants, an increasing interest for the Comet Assay was shown in the last decade and this versatile technique appears to be promising to detect the genotoxic effect of pollutants and to monitor the environment.
Bertrand Pourrut, Charles Homsy
doaj   +1 more source

THERMAL SHADOWS AND COMPOSITIONAL STRUCTURE IN COMET NUCLEI [PDF]

The Astrophysical Journal, 2011
We use a fully 3-dimensional thermal evolution model to examine the effects of a non-uniform surface albedo on the subsurface thermal structure of comets. Surface albedo markings cast "thermal shadows", with strong lateral thermal gradients. Corresponding compositional gradients can be strong, especially if the crystallization of amorphous water ice is
Guilbert-Lepoutre, A., Jewitt, D.
openaire   +2 more sources

Ice, Ice, Maybe? Investigating 46P/Wirtanen’s Inner Coma for Icy Grains

The Planetary Science Journal, 2023
The release of volatiles from comets is usually from direct sublimation of ices on the nucleus, but for very or hyperactive comets other sources have to be considered to account for the total production rates.
Theodore Kareta, John W. Noonan, Walter M. Harris, Alessondra Springmann   +3 more
doaj   +1 more source

Assessment of protein and DNA polymorphisms in corn (Zea mays) under the effect of non-ionizing electromagnetic radiation

Caryologia, 2023
Many reports highlight biological responses of crop plants after non-ionizing electromagnetic radiation (EMR) exposure based on the phenotypic and physiological levels.
Ekram Abdelhaliem, Hanan M. Abdalla, Ahmed A. Bolbol, Rania S. Shehata   +3 more
doaj   +1 more source

Loss of the Surface Layers of Comet Nuclei [PDF]

Space Science Reviews, 2008
The Deep Impact observations of low thermal inertia for comet 9P/Tempel 1 are of profound importance for the observations to be made by the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. While sub-surface sublimation is necessary to explain the observations, the depth at which this occurs is no more than 2–3 cm and possibly less.
Thomas, N., Alexander, C., Keller, H.
openaire   +6 more sources

Toxoplasma gondii infection can induce retinal DNA damage:an experimental study

International Journal of Ophthalmology, 2014
AIM: To detect whether Toxoplasma gondii (T. gondii) infection of mice can induce retinal DNA damage.METHODS: A total of 20 laboratory-bred male Swiss albino mice were used and divided into four groups:control group (non-infected animals); T ...
Nagwa Mostafa El-Sayed, Eman Mohamed Aly
doaj   +1 more source

Comets beyond 4 au: How pristine are Oort nuclei? [PDF]

Monthly Notices of the Royal Astronomical Society, 2022
Abstract The ESA mission Comet Interceptor will target an Oort or interstellar comet during its first approach to the Sun. Meanwhile, the Vera Rubin LSST Survey will observe hundreds of active comets per month beyond 4 au from the Sun, where water vapor pressure is expected to be too low to eject dust.
Fulle Marco, Lazzarin M, La Forgia F, Zakharov V V, Bertini I, Epifani E Mazzotta, Ammannito E, Buzzoni A, Capria M T, Carbognani A, Da Deppo V, Corte V Della, Fiscale S, Frattin E, Inno L, Migliorini A, Pernechele C, Rotundi A, Sindoni G, Tubiana C, Milani G, Aletti A, Bacci P, Baj G, Bellini F, Bryssinck E, Di Grazia M, Facchini M, Feraco M, Guido E, Ligustri R, Kugel F, Maestripieri M, Tirelli D, Valvasori A, Snodgrass C, Jones G H   +36 more
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The size distribution of Jupiter Family comet nuclei [PDF]

Monthly Notices of the Royal Astronomical Society, 2011
We present an updated cumulative size distribution (CSD) for Jupiter Family comet (JFC) nuclei, including a rigourous assessment of the uncertainty on the slope of the CSD. The CSD is expressed as a power law, N(>r_N) \propto r_N^{-q}, where r_N is the radius of the nuclei and q is the slope.
Snodgrass, Colin, Fitzsimmons, A., Lowry, S. C., Weissman, P.   +3 more
openaire   +6 more sources