401 research outputs found
Древнерусская надпись-граффито в аббатстве Сен-Жиль на юге Франции
The abbey of Saint-Gilles-du-Gard near Arles in the south of France was one of the most prominent pilgrimage sites in medieval Europe.Recent archaeological investigation has shown that construction of the abbey church, one of the most significant Romanesque pilgrimage churches in southern France, began ca. 1170/1180. The lower church (crypt) with the tomb of St. Giles (Lat. Aegidius, Fr. Gilles) and some of the walls of the upper church belong to that period.A well-preserved Cyrillic graffito was discovered on a pier of the upper church, close to the spot where the tomb of St. Giles is located in the crypt below. The text contains a prayer with a common formula: GI POMЪZI | RABU SVЪ|EMU SЬMKЪ|VI NINOSLA|VICHIU ‘Lord, help your servant Semko, son of Ninoslav.’ Palaeographic and linguistic analysis shows that the graffito is of Russian origin. It was probably made at some time between 1180 and 1250 by a pilgrim travelling from Russia to Santiago de Compostela, and it is the most geographically remote Old Russian graffito inscription discovered so far in western Europe.Одним из значительных паломнических центров средневековой Европы было аббатство Сен-Жиль-дю-Гар недалеко от Арля на Юге Франции. Согласно недавним археологическим исследованиям, возведение собора аббатства, одной из наиболее крупных позднероманских паломнических церквей на Юге Франции, началось около 1170/1180 года. К первой стадии строительства относятся нижний храм (крипта) с гробницей святого Эгидия (лат. Aegidius, фр. Gilles) и часть стен верхней церкви.Хорошо сохранившееся кириллическое граффито было обнаружено на колонне верхней церкви, расположенной рядом с тем местом, под котором в крипте находится гробница св. Эгидия. Текст состоит из молитвы, записанной при помощи типичной формулы: ГИ ПОМЪЗИ | РАБУ СВЪ|ЕМУ СЬМКЪ|ВИ НИНОСЛА|ВИЧЮ ‘Господи, помоги рабу своему Семку Нинославичу’. По палеографическим и лингвистическим данным граффито является древнерусским и датируется временем не позже конца XIII века, предпочтительно — не позже середины XIII века.Вероятно, найденное граффито было оставлено паломником, следовавшим из Руси в Сантьяго-де-Компостела примерно между 1180 и 1250 годами. На сегодняшний день это самая западная из выявленных древнерусских надписей-граффити
Stellar pollution and [Fe/H] in the Hyades
The Hyades open cluster presents a unique laboratory for planet formation and
stellar pollution studies because all of the stars have essentially the same
age and were born from the same cloud of gas. Furthermore, with an age of
roughly 650 Myr most of the intermediate and low mass stars are on the main
sequence. Given these assumptions, the accretion of metal rich material onto
the surface of a star during and shortly after the formation of planetary
systems should be evident via the enhanced metallicity of the star. Building on
previous work, stellar evolution models which include the effects of stellar
pollution are applied to the Hyades. The results of several Monte Carlo
simulations, in which the amount of accreted material is drawn at random from a
Gaussian distribution with standard deviation equal to half the mean, are
presented. An effective temperature-[Fe/H] relation is produced and compared to
recent observations. The theoretical predictions presented in this letter will
be useful in future searches for evidence of stellar pollution due to planet
formation. It is concluded that stellar pollution effects at the mean level of
>=2 Earth masses of iron are ruled out by current observational data.Comment: 10 pages, 3 figures, AASTeX, accepted to the ApJ
SPIRAL facility at GANIL : ion beam simulation and optimisation method for the CIME cyclotron injection system
International audienc
Characterization of nanomedicines’ surface coverage using molecular probes and capillary electrophoresis
International audienceA faithful characterization of nanomedicine (NM) is needed for a better understanding of their in vivo outcomes. Size and surface charge are studied with well-established methods. However, other relevant parameters for the understanding of NM behavior in vivo remain largely inaccessible. For instance, the reactive surface of nanomedicines, which are often grafted with macromolecules to decrease their recognition by the immune system, is excluded from a systematic characterization. Yet, it is known that a subtle modification of NMs' surface characteristics (grafting density, molecular architecture and conformation of macromolecules) is at the root of major changes in the presence of biological components. In this work, a method that investigates the steric hindrance properties of the NMs’ surface coverage based on its capacity to exclude or allow adsorption of well-defined proteins was developed based on capillary electrophoresis. A series of proteins with different molecular weights (MW) were used as molecular probes to screen their adsorption behavior on nanoparticles bearing different molecular architectures at their surface. This novel strategy evaluating to some degree a functionality of NMs can bring additional information about their shell property and might allow for a better perception of their behavior in the presence of biological components. The developed method could discriminate nanoparticles with a high surface coverage excluding high MW proteins from nanoparticles with a low surface coverage that allowed high MW proteins to adsorb on their surface. The method has the potential for further standardization and automation for a routine use. It can be applied in quality control of NMs and to investigate interactions between proteins and NM in different situations
Chemical composition of A and F dwarfs members of the Pleiades open cluster
Abundances of 18 chemical elements have been derived for 16 A (normal and
chemically peculiar CP) and 5 F dwarfs members of the Pleiades open cluster in
order to set constraints on evolutionary models. The abundances, rotational
velocities and microturbulent velocities were derived by iteratively adjusting
synthetic spectra to observations at high resolution (R~42000 and R~75000) and
high signal-to-noise (S/N) ratios. The abundances obtained do not exhibit any
clear correlation with the effective temperature nor the projected rotational
velocity. Interestingly, A stars exhibit larger star-to-star variations in C,
Sc, Ti, V, Cr, Mn, Sr, Y, Zr and Ba than F stars. F stars exhibit solar
abundances for almost all the elements. In A stars, the abundances of Si, Ti
and Cr are found to be correlated with that of Fe, the [X/Fe] ratios being
solar for these three elements. The derived abundances have been compared to
the predictions of published evolutionary models at the age of Pleiades (100
Myr). For the F stars, the predicted slight underabundances of light elements
and overabundances of Cr, Fe and Ni are indeed confirmed by our findings. For A
stars, the predicted overabundances in iron peak elements are confirmed in a
few stars only. The large scatter of the abundances in A stars, already found
in the Hyades, Coma Berenices and the UMa group and in field stars appears to
be a characteristic property of dwarf A stars. The occurence of hydrodynamical
processes competing with radiative diffusion in the radiative zones of the A
dwarfs might account for the found scatter in abundances.Comment: 7 pages, 3 figures, accepted in A&
Chemical composition of A and F dwarf members of the Coma Berenices open cluster
Abundances of 18 chemical elements have been derived for 11 A (normal and Am)
and 11 F dwarfs members of the Coma Berenices open cluster in order to set
constraints on evolutionary models including transport processes (radiative and
turbulent diffusion)calculated with the Montreal code. A spectral synthesis
iterative procedure has been applied to derive the abundances from selected
high quality lines in high resolution high signal-to-noise echelle spectra
obtained with ELODIE at the Observatoire de Haute Provence. The chemical
pattern found for the A and F dwarfs in Coma Berenices is reminiscent of that
found in the Hyades and the UMa moving group. In graphs representing the
abundances [X/H] versus the effective temperature, the A stars often display
abundances much more scattered around their mean values than the F stars do.
Large star-to-star variations are detected for A stars in their abundances
which we interpret as evidence of transport processes competing with radiative
diffusion. The F stars have solar abundances for almost all elements except for
Mg, Si, V and Ba. The derived abundances patterns, [X/H] versus atomic number,
for the slow rotator HD108642 (A2m) and the moderately fast rotator HD106887
(A4m) were compared to the predictions of self consistent evolutionary model
codes including radiative and different amounts of turbulent diffusion. None of
the models reproduces entirely the overall shape of the abundance pattern.
While part of the discrepancies between derived and predicted abundances may be
accounted for by non-LTE effects, the inclusion of competing processes such as
rotational mixing in the radiative zones of these stars seems necessary to
improve the agreement between observed and predicted abundance patterns.Comment: 25 pages, 20 figure
Determining the Physical Properties of the B Stars I. Methodology and First Results
We describe a new approach to fitting the UV-to-optical spectra of B stars to
model atmospheres and present initial results. Using a sample of lightly
reddened stars, we demonstrate that the Kurucz model atmospheres can produce
excellent fits to either combined low dispersion IUE and optical photometry or
HST FOS spectrophotometry, as long as the following conditions are fulfilled:
1) an extended grid of Kurucz models is employed,
2) the IUE NEWSIPS data are placed on the FOS absolute flux system using the
Massa & Fitzpatrick (1999) transformation, and
3) all of the model parameters and the effects of interstellar extinction are
solved for simultaneously.
When these steps are taken, the temperatures, gravities, abundances and
microturbulence velocities of lightly reddened B0-A0 V stars are determined to
high precision. We also demonstrate that the same procedure can be used to fit
the energy distributions of stars which are reddened by any UV extinction curve
which can be expressed by the Fitzpatrick & Massa (1990) parameterization
scheme.
We present an initial set of results and verify our approach through
comparisons with angular diameter measurements and the parameters derived for
an eclipsing B star binary. We demonstrate that the metallicity derived from
the ATLAS 9 fits to main sequence B stars is essentially the Fe abundance. We
find that a near zero microturbulence velocity provides the best-fit to all but
the hottest or most luminous stars (where it may become a surrogate for
atmospheric expansion), and that the use of white dwarfs to calibrate UV
spectrophotometry is valid.Comment: 17 pages, including 2 pages of Tables and 6 pages of Figures.
Astrophysical Jounral, in pres
Spectroscopy of Blue Stragglers and Turnoff Stars in M67 (NGC 2682)
We have analyzed high-resolution spectra of relatively cool blue stragglers
and main sequence turnoff stars in the old open cluster M67 (NGC 2682). We
attempt to identify blue stragglers whose spectra are least contaminated by
binary effects (contamination by a binary companion or absorption by
circumstellar material). These ``best'' stragglers have metallicities ([Fe/H] =
-0.05) and abundance ratios of the blue stragglers are not significantly
different from those of the turnoff stars. Based on arguments from
hydrodynamical models of stellar collisions, we assert that the current upper
limits for the lithium abundances of all blue stragglers observed in M67 (by us
and others) are consistent with no mixing during the formation process,
assuming pre-main sequence and main sequence depletion patterns observed for
M67 main sequence stars. We discuss composition signatures that could more
definitively distinguish between blue straggler formation mechanisms in open
cluster stars.
We confirm the spectroscopic detection of a binary companion to the straggler
S 1082. From our spectra, we measure a projected rotational speed of 90+/-20
km/sec for the secondary, and find that its radial velocity varies with a
peak-to-peak amplitude of ~ 25 km/sec. Because the radial velocities do not
vary with a period corresponding to the partial eclipses in the system, we
believe this system is currently undergoing mass transfer. In addition we
present evidence that S 984 is a true blue straggler (and not an unresolved
pair). If this can be proven, our detection of lithium may indicate a
collisional origin.Comment: 20 pages, 4 figures, to appear in October 2000 A
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