Martian Fluid Evolution Recorded in Smectite from the Northwest Africa (Nwa) 817 Nakhlite Meteorite [abstract]

No abstract available

Multiple Aqueous Events in the Nakhlite Meteorite North West Africa (NWA)

Geological records suggest the past existence of abundant water flowing freely on Mars’ surface. Most of this aqueous activity appears to have been restricted to early Mars and although aqueous alteration by thin films of water or acid fog may still occur today, evidence suggests that liquid water has not existed at the surface for the last 3 Ga [1]. The Nakhlites, which are 1.3 Ga old Martian meteorites, contain mineralogical proof for the existence of liquid water within the shallow Martian crust duting the Amazonian [2]. To understand the nature of the water-rich fluids and conditions responsible for aqueous alteration on Mars, thorough characterization of chemical and mineralogical changes resulting from aqueous processes is essential.<p></p> The Nakhlite meteorite North West Africa (NWA) 817 was discovered in the Saharan desert (Morocco) as a single stone of 104g by meteorite hunters in 2000 [4]. In common with most other Nakhlite meteorites, NWA 817 presents mineralogical evidence of interactions with low temperature water-bearing fluids on Mars [5]. Here, we present a petrological and chemical reinvestigation of the alteration products of NWA 817. Our study reveals evidence for multiple fluid infiltrations in Mars subsurface during the Amazonian.<p></p&gt

Secondary Minerals in the Nakhlite Meteorite Yamato 000593: Distinguishing Martian from Terrestrial Alteration Products

The nakhlites are olivine-bearing clinopyroxenites that formed in a Martian lava flow or shallow intrusion 1.3 Ga ago [1, 2]. They are scientifically extremely valuable because they interacted with water-bearing fluids on Mars [3]. Fluid-rock interactions led to the precipitation of secondary minerals, many of which are hydrous. The secondary minerals consist in a mixture of poorly crystalline smectitic material and Fe-oxide, collectively called “iddingsite”, but also carbonate and sulphate [4]. The proportion, chemistry and habit of the secondary minerals vary between members of the Nakhlite group, which is thought to reflect compositional variation of the fluid within the Martian crust [5]. However, some secondary minerals are quite similar to terrestrial alteration products and thus the chemical and textural variations could also reflect terrestrial contamination (deposition or exchange). Identifying the origin of the secondary minerals is not straightforward but essential to unravel the Martian fluid chemistry and conditions.<p></p> Yamato 000593 (Y-000593) is a nakhlite meteorite that was discovered in Antarctica near the Yamato Mountains by the Japanesse Antarctic Research Expedition in 2000-2001 [6]. Most of the meteorite is covered by a black shiny fusion crust but it also has deep erosion features in its underside that probably formed by freeze- thaw cycles. As in most other Nakhlites, Y 000593 contains iddingsite-like alteration products believed to have been formed on Mars because they have devolatilization features at the vicinity of the fusion crust [7]. Additional evidence of Martian aqueous alteration is the presence of laihunite, a high temperature oxidative alteration product of fayalitic olivine [8].<p></p> The secondary minerals in Y-000593 can provide a powerful insight into the Martian hydrosphere from high to low temperature environments with implications for the origin, cycling, and availability of water on Mars. However, it is highly likely that some secondary minerals have formed on Earth which can biased our understanding of the Martian groundwater chemistry. With this in mind, we are trying to identify all the different secondary minerals and document their spatial and textural relations, their mineralogy and chemistry to better constrain their possible origin and the impact that terrestrial fluids may have had on the Martian alteration products.<p></p&gt

A perspective on the Healthgrid initiative

This paper presents a perspective on the Healthgrid initiative which involves European projects deploying pioneering applications of grid technology in the health sector. In the last couple of years, several grid projects have been funded on health related issues at national and European levels. A crucial issue is to maximize their cross fertilization in the context of an environment where data of medical interest can be stored and made easily available to the different actors in healthcare, physicians, healthcare centres and administrations, and of course the citizens. The Healthgrid initiative, represented by the Healthgrid association (http://www.healthgrid.org), was initiated to bring the necessary long term continuity, to reinforce and promote awareness of the possibilities and advantages linked to the deployment of GRID technologies in health. Technologies to address the specific requirements for medical applications are under development. Results from the DataGrid and other projects are given as examples of early applications.Comment: 6 pages, 1 figure. Accepted by the Second International Workshop on Biomedical Computations on the Grid, at the 4th IEEE/ACM International Symposium on Cluster Computing and the Grid (CCGrid 2004). Chicago USA, April 200

Observations of Doppler Boosting in Kepler Lightcurves

Among the initial results from Kepler were two striking lightcurves, for KOI 74 and KOI 81, in which the relative depths of the primary and secondary eclipses showed that the more compact, less luminous object was hotter than its stellar host. That result became particularly intriguing because a substellar mass had been derived for the secondary in KOI 74, which would make the high temperature challenging to explain; in KOI 81, the mass range for the companion was also reported to be consistent with a substellar object. We re-analyze the Kepler data and demonstrate that both companions are likely to be white dwarfs. We also find that the photometric data for KOI 74 show a modulation in brightness as the more luminous star orbits, due to Doppler boosting. The magnitude of the effect is sufficiently large that we can use it to infer a radial velocity amplitude accurate to 1 km/s. As far as we are aware, this is the first time a radial-velocity curve has been measured photometrically. Combining our velocity amplitude with the inclination and primary mass derived from the eclipses and primary spectral type, we infer a secondary mass of 0.22+/-0.03 Msun. We use our estimates to consider the likely evolutionary paths and mass-transfer episodes of these binary systems.Comment: 8 pages, 4 figures, ApJ 715, 51 (v4 is updated to match the published version, including a note added in proof with measured projected rotational velocities)

Low-Ca Pyroxenes in the Nwa 998 Nakhlite Meteorite: Reactive Products of Olivine-Plagioclase Mineral Assemblage [abstract]

No abstract available

Discovery of the Optical Counterparts to Four Energetic Fermi Millisecond Pulsars

In the last few years, over 43 millisecond radio pulsars have been discovered by targeted searches of unidentified gamma-ray sources found by the Fermi Gamma-Ray Space Telescope. A large fraction of these millisecond pulsars are in compact binaries with low-mass companions. These systems often show eclipses of the pulsar signal and are commonly known as black widows and redbacks because the pulsar is gradually destroying its companion. In this paper, we report on the optical discovery of four strongly irradiated millisecond pulsar companions. All four sources show modulations of their color and luminosity at the known orbital periods from radio timing. Light curve modelling of our exploratory data shows that the equilibrium temperature reached on the companion's dayside with respect to their nightside is consistent with about 10-30% of the available spin-down energy from the pulsar being reprocessed to increase the companion's dayside temperature. This value compares well with the range observed in other irradiated pulsar binaries and offers insights about the energetics of the pulsar wind and the production of gamma-ray emission. In addition, this provides a simple way of estimating the brightness of irradiated pulsar companions given the pulsar spin-down luminosity. Our analysis also suggests that two of the four new irradiated pulsar companions are only partially filling their Roche lobe. Some of these sources are relatively bright and represent good targets for spectroscopic follow-up. These measurements could enable, among other things, mass determination of the neutron stars in these systems.Comment: 11 pages, 5 tables, 1 figure, 4 online tables. ApJ submitted and referee

Finding unique PCR products on distributed databases

Thanks to the development of genetic engineering, various kinds of genomic information are being unveiled. Hence, now, it becomes feasible to study in molecular biology by analyzing the entire genomic information. On the other hand, the quantity of the genomic information stocked in database is increasing day after day. In order to process the whole information, we have to develop an effective method to deal with lots of data. It is indispensable not only to make an effective and rapid algorithm but also to use high-speed computer resource so as to analyze the biological information. For this purpose, as one of the most promised computing environments, the grid computing architecture has appeared recently. The European Data Grid (EDG) is one of the grid com-puting environments. In the first stage of designing hybridization probes and PCR primers, it is extremely important to find genuinely unique sequence on a target genome. We deployed a novel method to design PCR primers, which takes into account not only the specificity of the primer itself but also the uniqueness of the product length. In this paper, we improve our proposed method to find unique PCR products on distributed databases. We show also the sequences found by our method, which can not be uniquely observed by any probe sequence but by a pair of PCR primers on S. cerevisiae genome. 1