Search results for "MARS"

On the accretion history of galaxy clusters: temporal and spatial distribution

2020

We analyse the results of an Eulerian AMR cosmological simulation in order to quantify the mass growth of galaxy clusters, exploring the differences between dark matter and baryons. We have determined the mass assembly histories (MAHs) of each of the mass components and computed several proxies for the instantaneous mass accretion rate (MAR). The mass growth of both components is clearly dominated by the contribution of major mergers, but high MARs can also occur during smooth accretion periods. We explored the correlations between MARs, merger events and clusters' environments, finding the mean densities in $1 \leq r/R_{200m} \leq 1.5$ to correlate strongly with $\Gamma_{200m}$ in massive …

The Origin of Life: More Questions Than Answers

1988

AbstractMore than 30 years of experimentation on the origin of life in the fields of chemical and molecular evolution have led to a better perception of the immensity of the problem of the origin of life on Earth rather than to its solution. At present all discussions on principal theories and experiments in the field either end in stalemate or in a confession of ignorance. New lines of thinking and experimentation must be tried. The continued exploration of our solar system, especially a better knowledge of Mars and Venus, of comets and carbonaceous meteorites may also lead to a better understanding of the prebiotic environment on Earth and will thus help us to design more appropriate preb…

Studies of astrophysically interesting nucleus23Al

2010

We have studied the β-delayed proton decay of 23Al with a novel detector setup at the focal plane of the MARS separator at the Texas A&M University to resolve existing controversies about the proton branching of the IAS in 23Mg and to determine the absolute proton branchings by combining our results to the latest βγ-decay data. We have made also a high precision mass measurement of the ground state of 23Al to establish more accurate proton separation energy of 23Al. Here the description of the used techniques along with preliminary results of the experiments are given.

Phononic crystals: Harnessing the propagation of sound, elastic waves, and phonons

2016

Comptes Rendus Physique - In Press.Proof corrected by the author Available online since jeudi 3 mars 2016

Methodological basis and the cogency of criticism: the cases of Clapham (1922) and Sraffa (1926)

1998

A view of extraterrestrial soils

2009

International audience; The nature of soils on celestial bodies other than Earth is a growing area of research in planetary geology. However, disagreement over the significance of these deposits arises in part due to the lack of a unified concept and definition of soil in the literature. The pragmatic definition “medium for plant growth” is taken by some to imply the necessity of biota for soil to exist, and has been commonly adopted in the planetary science community. In contrast, a more complex and informative definition bases on scientific theory: soil is the (bio)geochemically/physically altered material at the surface of a planetary body that encompasses surficial extraterrestrial tell…

Zvaigžņotā Debess: 2009, Pavasaris (203)

2009

Contents: E.R.Mustel, President of the Astronomical Council of the USSR Academy of Sciences. Congratulations to Editorial Board of “Zvaigžņotā debess” ; Z.Alksne. Gould’s Belt ; I.Daube. At the Radioastrophysical Observatory of the Latvian Academy of Sciences ; Z.Alksne, A.Alksnis. Lopsided Galaxies ; A.Alksnis. HII Region Gum 29 – a Stellar Nursery ; D.Docenko. On Collision of Asteroid 2008 TC3 with the Earth ; V.Lapoška. On „Leap Second” ; I.Vilks, M.Gills. Beginning of the International Year of Astronomy in Paris: Impressions by Latvian Delegates ; J.Jaunbergs. Equatorial Ridge on Iapetus ; M.Sudārs. Space Shuttle Is Not Likely to Retire Next Year ; I.Vilks. Planet Satellite Names in Lat…

Polarization and high resolution parametric spectral analysis applied to the seismic signals recorded on the Marsili submarine volcano

2008

Electrochemistry of iron oxide pigments (earths) from pictorial microsamples attached to graphite–polyester composite electrodes

2001

The electrochemical response of different iron pigments attached to graphite–polyester composite electrodes is described. Characteristic differential pulse voltammetric profiles were obtained for green earth, iron oxide red, Mars black, ochre yellow, Sienna raw, umber raw and Van Dyke brown. Proton-assisted reductive dissolution processes occur at the three-phase boundary of the substrate electrode–attached solid–electrolyte solution system. Microsamples extracted from polychromed sculptures, canvas paintings, wall paintings, altarpieces and panel paintings from Spain, Ethiopia and Italy from the 12th to the 20th centuries were electrochemically identified in agreement with polarized light …

The Impact of the Changing Climate on the Supply and Recycling of Nitrate

2009

A high proportion of the nitrogen found in lakes and rivers is present in the form of nitrate. The concentration of nitrate in many surface waters has increased over the last forty years (OECD, 1982; Roberts and Marsh, 1987; Johnes and Burt, 1993). The main source of nitrate is diffuse drainage from agricultural land (Vinten and Smith, 1993) but point sources can be important in populated areas (Jarvey et al., 1998). In 1991, the European Union introduced the Nitrates Directive (91.676) to protect waters from pollution by nitrate leached from agricultural land.