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The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created.

Context. NGC 205 is a peculiar dwarf elliptical galaxy hosting in its center a population of young blue stars. Their origin is still matter of debate, the central fresh star formation activity possibly being related to dynamical interactions between NGC 205 and M 31.

Context.About 500 new variable stars enter the General Catalogue of Variable Stars (GCVS) every year. Most of them however lack spectroscopic observations, which remains critical for a correct assignement of the variability type and for the understanding of the object.

Context.The Sagittarius dwarf spheroidal galaxyis the nearest neighbor of the Milky Way. Moving along a short period quasi-polar orbit within the Halo, it is being destroyed by the tidal interaction with our Galaxy, losing its stellar content along a huge stellar stream.

Context.The Sagittarius (Sgr) dwarf spheroidal galaxy is currently being disrupted under the strain of the Milky Way. A reliable reconstruction of Sgr star formation history can only be obtained by combining core and stream information.

We present a quantitative comparison between the Horizontal Branch morphology in the core of the Sagittarius dwarf spheroidal galaxy (Sgr) and in a wide field sampling a portion of its tidal stream (Sgr Stream), located tens of kpc away from the center of the parent galaxy. We find that the Blue Horizontal Branch (BHB) stars in that part of the Stream are five times more abundant than in the Sgr core, relative to Red Clump stars. The difference in the ratio of BHB to RC stars between the two fields is significant at the $\ga$$4.8\sigma$level. This indicates that the old and metal-poor population of Sgr was preferentially stripped from the galaxy in past peri-Galactic passages with respect to the intermediate-age metal rich population that presently dominates the bound core of Sgr, probably due to a strong radial gradient that was settled within the galaxy before its disruption. The technique adopted in the present study allows to trace population gradients along the whole extension of the Stream.

We present a statistically decontaminated Color Magnitude Diagram of a $1\degr\times 1\degr$field in the core of the Sagittarius dSph galaxy. Coupling this CMD with the most recent metallicity distributions obtained from high resolution spectroscopy we derive robust constraints on the mean age of the stellar population that dominates the galaxy (Pop A). Using three different sets of theoretical isochrones in the metallicity range $-0.4\le [{\rm M/H}]\le -0.7$and taking into consideration distance moduli in the range $16.90\le (m-M)_0\le 17.20$we find that the mean age of Pop A is larger than 5 Gyr, and the best-fit value is age = $8.0\pm 1.5$Gyr. Since Pop A provides the vast majority of the M giants that traces the tidal stream of Sgr dSph all over the sky, our estimate resolves the so called “M giant conundrum” (Majewski et al. 2003, ApJ, 599, 1082). The time needed by the M giants that currently populates the stream to diffuse within the main body of Sgr and to reach the extremes of the tidal tails once torn apart from the parent galaxy ($\simeq$$3{-}4$Gyr) can be easily accommodated into the time lapsed since their birth ($\simeq$$5.5{-}9.5$Gyr).

We present iron and αelement (Mg, Ca, Ti) abundances for a sample of 15 Red Giant Branch stars belonging to the main body of the Sagittarius dwarf Spheroidal galaxy. Abundances have been obtained from spectra collected using the high resolution spectrograph FLAMES-UVES mounted at the VLT. Stars of our sample have a mean metallicity of [ Fe/H$]=-0.41\pm0.20$with a metal-poor tail extending to [ Fe/H$]=-1.52$. The αelement abundance ratios are slightly subsolar for metallicities higher than $\rm [Fe/H]\ga-1$, suggesting a slow star formation rate. The [ α/Fe] of stars having $\rm [Fe/H]<-1$are compatible to what observed in Milky Way stars of comparable metallicity.

In this study, alternatives to corrosion-resistant cadmium coatings on high strength steel fasteners are explored. Nanocrystalline Zn-Ni and Zn-Ni-Co electrodeposits, synthesized by electrochemical deposition, were analyzed by potentiodynamic polarization in a 1M NaCl aqueous solution, to determine the corrosion behaviour of the alloys. Sample coatings were characterized using scanning electron microscopy to examine differences in surface morphology that can affect corrosion resistance. Energy dispersive x-ray spectroscopy was used to relate composition to corrosion resistance and to characterize the corrosion behavior during polarization. All coatings showed corrosion potentials at equivalent, or lower values than that of cadmium, suggesting that both alloys are viable as cadmium replacements. Specific compositions showed slightly passivating regions, but the brittle film formed during polarization is unstable. Comparatively, Zn-Ni shows a better resistance to corrosion than Zn-Ni-Co. The effect of composition on the corrosion resistance can be explained on the basis of the sacrificial depletion of Zn over Ni.

Aim of the study: We intended to use a radioguided technique for pre-operative localization of neck node recurrences in patients with papillary thyroid cancer (PTC) already submitted to thyroidectomy and radioiodine treatment. Patients and methods: We selected 20 patients affected by PTC with evidence of neck nodes recurrences at ultrasound examination. Our method has been derived from the Radioguided Occult Lesion Localization technique used for pre-operative localization of occult breast lesions. The technique involves the inoculation of human albumin macroaggregates labeled with radioactive technetium (0.4 mCi in a volume of 0.05 ml) directly in the suspicious lesion, under ultrasound guidance. The persistence of the radioactive tracer in the nodes is confirmed by a scintigraphy performed 2 h after injection. During surgery, a gamma detecting probe is used to locate the suspicious lesions as “hot spots”. Results: Fifty lymph-nodes were injected with the tracer. All radiolabeled lymph-nodes were located and removed during surgery. At histology, metastasis of PTC was confirmed in 38/50 (76%) lymph-nodes. At least one metastatic lymph-node per patient was removed. In 8/20 (40%) patients, reactive lymphoid hyperplasia was found in 12/50 (24%) lymph-nodes. Conclusions: This radioguided technique has been highly effective for localization and surgical treatment of suspicious lymph-node detected at neck ultrasound and may play a valuable role in case of node metastases of thyroid cancer that show no radioiodine uptake.

Aims. We present lithium abundance determination for a sample of K giant stars in the Galactic bulge. The stars presented here are the only 13 stars with a detectable lithium line (6767.18??) among ~400 stars for which we have spectra in this wavelength range, half of them in Baade's Window (b=-4?) and half in a field at b=-6?.Methods. The stars were observed with the GIRAFFE spectrograph of FLAMES mounted on VLT, with a spectral resolution of R?20000. Abundances were derived from spectral synthesis and the results are compared with those of stars with similar parameters, but no detectable Li?line.Results. We find 13 stars with a detectable Li?line, among which 2 have abundances A(Li)>2.7. No clear correlations were found between the Li abundance and those of other elements. With the exception of the two most Li? rich stars, the others follow a fairly tight A(Li)-Teffcorrelation.Conclusions. There is strong indication of a Li?production phase during the red giant branch (RGB), acting either on a very short timescale, or selectively only in some stars. That the proposed Li?production phase is associated with the RGB?bump cannot be excluded, although our targets are significantly brighter than the predicted RGB?bump magnitude for a population at 8?kpc.

Context. High resolution observations of the asteroids Iris and Juno have been performed by means of the UV-Visual Echelle Spectrograph (UVES) at the European Southern Observatory (ESO) Very Large Telescope (VLT) to obtain the effective accuracy of the spectrograph's radial velocity. The knowledge of this quantity has important bearings on studies searching for a variability in the fine structure constant carried out with this instrument.Aims. Asteroids provide a precise radial velocity reference at the level of 1?m?s-1, which allows for instrumental calibration and the recognition of small instrumental drifts and calibration systematics. In particular, radial velocity drifts due to nonuniform slit illumination and slit optical misalignment in the two UVES spectrograph arms can be investigated.Methods. We compare the position of the solar spectrum reflected by the asteroids with the solar wavelength positions and with that of asteroid and twilight observations at other epochs to asses the UVES instrumental accuracy.Results. We observe radial velocities offsets in the range of ?10-50?m?s-1, likely due to a nonuniform slit illumination. However, no radial velocity patterns with wavelengths are detected and the two UVES arms provide consistent radial velocities. These results suggest that the detected ??/?variability by Levshakov et?al. (2007) deduced from a drift of -180 ? 85?m?s-1? at zabs?=?1.84, between two sets of Fe?II?lines falling in the two UVES arms, may be real or induced by other kinds of systematics than those investigated here. The proposed technique allows us to make a real time quality check of the spectrograph and should be followed for very accurate measurements.

The effect of cerium on corrosion inhibition of Al 6061 T6/Al2O3p 10% (v/v) metal matrix composite in aerated 3.5% NaCl solution after different immersion times at room temperature and pressure was investigated.

The effect of cerium on corrosion inhibition of Al 6061 T6/Al2O3p 10% (v/v) metal matrix composite in aerated 3.5% NaCl solution after different immersion times at room temperature and pressure was investigated. Experimental tests were conducted at different inhibitor agent concentrations (0, 200, 1000 and 2000 ppm of cerium) and for exposure times ranging from 2 h to 30 days. Corrosion inhibition power evaluation and surface layer characterization have been carried out by electrochemical (polarization potentiodynamic curves and impedance measurements) and free corrosion tests followed by several instrumental analyses (optical microscopy, x-ray photoelectron spectroscopy, scanning electron microscopy). Electrochemical data have shown that cerium compounds offer a noticeable inhibition level against localized corrosion in all considered cases and that the maximum protective power against corrosion attack is evident when the inhibitor is added at a 200 ppm concentration. Surface analysis revealed chemical and morphological characteristics of the passive layer. In particular, a higher amount of inhibitor led to the formation of a surface film with a higher content of cerium but without homogeneous distribution. This behaviour decreased the protection power of the passive layer while increasing composite substrate corrosion tendency. Copyright © 2002 John Wiley & Sons, Ltd.

Sexual homicide by juveniles is a rare phenomenon, and information regarding the psychological and behavioral characteristics of this group is limited. No studies exist which have investigated anger experience and styles of anger expression, and the relationship between anger, sadistic personality disorder, and psychopathy, in this type of youthful offender. These areas were explored by evaluating 14 juvenile sexual homicide offenders through clinical assessment, the State-Trait Anger Expression Inventory (STAXI), the Schedule for Nonadaptive and Adaptive Personality (SNAP), the Revised Psychopathy Checklist (PCL-R), and review of correctional records. Descriptive information for the STAXI scales and internal consistency data are presented. Trait Anger was significantly higher than State Anger for the youth, but still comparable to adolescent norms. The difference between Anger-In and Anger-Out scale scores was not significant. Unexpectedly, Anger Control scale scores were significantly higher than Anger Out scale scores, clinically consistent with efforts by some of these boys to resist sadistic impulses. Those four (31%) participants who met criteria for sadistic personality had significantly higher Anger-Out scale scores than those without the disorder, and were also higher on Trait Anger to a marginally significant degree. Psychopathy was significantly negatively associated with Anger Control. This study is intended to contribute to the scant literature on juvenile sexual homicide, and lends some support to the validity and utility of sadistic personality disorder as a diagnosis in younger forensic populations. The findings did not support the contention that this form of violence is necessarily an outgrowth of excessive anger.

We have constructed a plasmid, pLM8, containing the coding sequence of the mature human apoA‐1 fused to the coding sequence of the IgG‐binding domains of protein A (PA) from Staphylococcus aureus. The hybrid gene is transcribed in Escherichia coli under the control of a heat‐sensitive repressor, leading to the synthesis of large amounts of hybrid protein (apoA‐1–PA). The hybrid protein was purified by denaturation with urea and alkali, renaturation and affinity chromatography on an IgG Sepharose column. ApoA‐1–PA is soluble and has an Mr of 316 kd, as determined by gel filtration. This is five times the monomer size of 62 kd, predicted from the sequence and found by SDS‐PAGE analysis. Cell surface binding activity of the hybrid protein was tested using two different cell types (J774 macrophages and Fao hepatocytes) and compared to human high density lipoprotein (HDL). High‐affinity binding was found for both ligands in both cell lines (Kd = 3.4 X 10(‐8)M in Fao cells, 4.9 X 10(‐8) M in J774 cells for apoA‐1–PA and 3.0 X 10(‐8) M in Fao cells, 2.8 X 10(‐8) M in J774 cells for HDL), with approximately 2 X 10(5) high‐affinity binding sites per cell. ApoA‐1–PA and HDL effectively competed with each other for binding to the cell surface. Additionally, they both bound to a 110‐kd polypeptide on a ligand blot, identifying an HDL receptor. The binding parameters of HDL were very similar to those of apoA‐1–PA.(ABSTRACT TRUNCATED AT 250 WORDS)

The localization of adenosine receptors in rat testicular cells was investigated by evaluating the binding of cyclohexyladenosine (CHA) to somatic and germ cells and by assessing the effect of purine nucleosides on the function of testicular cells. Most of the specific binding of CHA in the testicular homogenate was found in the seminiferous tubule fraction, with little specific binding present in the interstitial compartment. Specific binding was also detected in a total-cell suspension prepared by dispersion of the seminiferous tubules. However, the specific activity of the binding did not increase when such a suspension was fractionated to produce germ cells at different stages of spermatogenesis. Adenosine receptors were present in the crude particulate fraction prepared from testes of rats from 10 to 90 days of age. While the affinity of these receptors did not vary as the testis matured, the number of binding sites per testis increased markedly up to 60 days after birth. Conversely, when binding activity was expressed per mg of testicular protein, no major changes in the specific activity of the binding were detected in testes up to 90 days of age. Sertoli cell-enriched cultures possessed a large number of binding sites, with a receptor density of 722 ± 147 fmoles bound/mg protein (mean ± SE; n = 5) and an affinity constant (Kd) of 1–2 nM. Among the characteristics of this binding site were kinetics constants and specificity similar to those measured in total particulate fractions of the testis and in the brain. Specific binding of CHA was not detected in cultures of testicular peritubular cells. In agreement with the binding study, the adenosine analog phenylisopropyladenosine (PIA) inhibited cyclic adenosine 3′ :5′-monophosp hate (cAMP) and estrogen accumulations which were dependent on follicle-stimulating hormone (FSH) Sertoli cell-enriched cultures. Such inhibitory activity was present in cells on different days of culture and after contaminating germ cells had been removed by brief hypotonic treatment. In addition, accumulation of cAMP was inhibited by PIA when whole testes or mechanically dispersed testes were exposed to FSH in vitro.These data indicate that adenosine receptors observed in the testis are mainly localized in the Sertoli cell of the seminiferous tubules, and that these receptors are functional and associated with an inhibition of cell response.

The human apoAI gene was expressed in E. coliby in‐frame fusion to a modified β‐galactosidase gene present in plasmid pUR291. The fused β‐galactosidase‐apoAI gene product was expressed at a high level and was recognized by an anti‐human apoAI antiserum. Besides the fused protein, at least one degradation product having an Mrsimilar to that of β‐galactosidase was present in high amounts in bacterial extracts. These results and those of a pulse‐chase experiment indicate that degradation took place only in the apoAI moiety of the chimeric protein.

ADP-ribosylation factors (ARFs) are approximately 20-kDa proteins that act as GTP-dependent allosteric activators of cholera toxin. With deoxyinosine-containing degenerate oligonucleotide primers corresponding to conserved GTP-binding domains in ARFs, the polymerase chain reaction (PCR) was used to amplify simultaneously from human DNA portions of three ARF genes that include codons for 102 amino acids, with intervening sequences. Amplification products that differed in size because of differences in intron sizes were separated by agarose gel electrophoresis. One amplified DNA contained no introns and had a sequence different from those of known ARFs. Based on this sequence, selective oligonucleotide probes were prepared and used to isolate clone psi ARF 4, a putative ARF pseudogene, from a human genomic library in lambda phage EMBL3. Reverse transcription-PCR was then used to clone from human poly(A)+ RNA the cDNA corresponding to the expressed homolog of psi ARF 4, referred to as human ARF 4. It appears that psi ARF 4 arose during human evolution by integration of processed ARF 4 mRNA into the genome. Human ARF 4 differs from previously identified mammalian ARFs 1, 2, and 3. Hybridization of ARF 4-specific oligonucleotide probes with human, bovine, and rat RNA revealed a single 1.8-kilobase mRNA, which was clearly distinguished from the 1.9-kilobase mRNA for ARF 1 in these tissues. The PCR provides a powerful tool for investigating diversity in this and other multigene families, especially with primers targeted at domains believed to have functional significance.

We have constructed a plasmid, pLM8, containing the coding sequence of the mature human apoA‐1 fused to the coding sequence of the IgG‐binding domains of protein A (PA) from Staphylococcus aureus. The hybrid gene is transcribed in Escherichia coli under the control of a heat‐sensitive repressor, leading to the synthesis of large amounts of hybrid protein (apoA‐1–PA). The hybrid protein was purified by denaturation with urea and alkali, renaturation and affinity chromatography on an IgG Sepharose column. ApoA‐1–PA is soluble and has an Mr of 316 kd, as determined by gel filtration. This is five times the monomer size of 62 kd, predicted from the sequence and found by SDS‐PAGE analysis. Cell surface binding activity of the hybrid protein was tested using two different cell types (J774 macrophages and Fao hepatocytes) and compared to human high density lipoprotein (HDL). High‐affinity binding was found for both ligands in both cell lines (Kd = 3.4 X 10(‐8)M in Fao cells, 4.9 X 10(‐8) M in J774 cells for apoA‐1–PA and 3.0 X 10(‐8) M in Fao cells, 2.8 X 10(‐8) M in J774 cells for HDL), with approximately 2 X 10(5) high‐affinity binding sites per cell. ApoA‐1–PA and HDL effectively competed with each other for binding to the cell surface. Additionally, they both bound to a 110‐kd polypeptide on a ligand blot, identifying an HDL receptor. The binding parameters of HDL were very similar to those of apoA‐1–PA.(ABSTRACT TRUNCATED AT 250 WORDS)

This paper describes the production of a recombinant protein from the expression system based on the methylotrophic yeast Pichia pastoris. Efficient production of rat high-mobility-group 1 (HMG1) protein was obtained using the system. Two forms of HMG1 were secreted into the culture medium: a 24.5-kDa species corresponding to the native HMG1 and a 32-kDa glycosylated derivative. Non-glycosylated recombinant HMG1 was purified easily and shown to possess the same DNA-binding properties as HMG1 purified from calf thymus. Plasmid DNA complexed to the recombinant HMG1 is taken up by a variety of mammalian cells in culture. Transient expression of a luciferase reporter gene was observed. Under selective conditions, stable expression of a neomycin gene was established as a result of integration into the genome. HMG1-mediated gene delivery was as efficient as calcium phosphate-mediated transfection but without associated cell damage. In addition, stable transfectants obtained after selection for G418 resistance usually integrated only one copy of the transfected DNA in contrast to the high unpredictable number obtained by the calcium phosphate method. HMG1 transfection complexes were not toxic to cultured cells, even at high concentrations.

The human apoAI gene was expressed in E. coliby in-frame fusion to a modified β-galactosidase gene present in plasmid pUR291. The fused β-galactosidase-apoAI gene product was expressed at a high level and was recognized by an anti-human apoAI antiserum. Besides the fused protein, at least one degradation product having an Mrsimilar to that of β-galactosidase was present in high amounts in bacterial extracts. These results and those of a pulse-chase experiment indicate that degradation took place only in the apoAI moiety of the chimeric protein.

Transcription factor CREM (cAMP-responsive element modulator) plays a pivotal role in the nuclear response to cAMP in neuroendocrine cells. We have previously shown that follicle-stimulating hormone (FSH) directs CREM expression in male germ cells. The physiological importance of FSH in Sertoli cell function prompted us to analyze its effect on CREM expression in these cells. We observed a dramatic and specific increase in the CREM isoform ICER (inducible cAMP early repressor) expression, with a peak 4 h after FSH treatment of primary Sertoli cells. Interestingly, induced levels of ICER protein persist for a considerably longer time. Induction of the repressor ICER accompanies early down-regulation of the FSH receptor transcript, which leads to long-term desensitization. Here we show that ICER represses FSH receptor expression by binding to a CRE-like sequence in the regulatory region of the gene. Our results confirm the crucial role played by CREM in hormonal control and suggest its role in the long-term desensitization phenomenon of peptide membrane receptors.

Growth‐induced defects in lysozyme crystals were observed by white‐beam and monochromatic X‐ray topography at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL). The topographic methods were non‐destructive to the extent that traditional diffraction data collection could be performed to high resolution after topography. It was found that changes in growth parameters, defect concentration as detected by X‐ray topography, and the diffraction quality obtainable from the crystals were all strongly correlated. In addition, crystals with fewer defects showed lower mosaicity and higher diffraction resolution as expected.

Endothelin (ET) is an extremely potent vasoconstrictor peptide of 21 amino acids, originally found in the supernatant of cultured vascular endothelial cells. To gain insights into its biosynthetic pathway, we expressed a synthetic RNA coding for the 212-amino acid precursor of human ET-1 (preproET-1) in Xenopus oocytes. Cell homogenates and oocyte incubation medium were tested by RIA using an anti-ET-1 serum. ET-1-like immunoreactivity was detected in oocytes injected with preproET-1 synthetic RNA but not in control oocytes and was much higher in medium than in cell homogenates. When preproET-1 was expressed in oocytes treated with monensin, a dramatic decrease in secretion of immunoreactive material was observed, indicating that secretion is mediated by the Golgi complex. ET-1-like immunoreactive material present in oocyte incubation medium was fractionated by reverse-phase HPLC into two main peaks, corresponding to the retention times of human big ET-1 and ET-1. Incubation medium of oocytes expressing the synthetic preproET-1 RNA elicited a characteristic vasoconstrictor response on rabbit vena cava, consistent with the biological activity that would be predicted from the amount of ET-1-like immunoreactivity measured. These results suggest that common pathways of ET maturation exist in widely different cells and that Xenopus oocytes may represent a useful tool in studying the cell biology of ET-1 synthesis.

Nicotinic acetylcholine receptors (nAcChoRs) of skeletal muscle are heterosubunit ligand-gated channels that mediate signal transmission from motor nerves to muscle. While cloning murine nAcChoR subunits, to gain an insight into the receptor diversity across species, we detected two forms of gamma subunits in the myogenic C2C12 cell line. Both forms are functional when expressed in Xenopus oocytes. One gamma subunit [long gamma (gamma 1)] was almost identical to that previously cloned in the murine BC3H-1 tumor cell line. The second form of gamma subunit [short gamma (gamma s)] lacked 156 bp (52 amino acids) in the extracellular N terminus, adjoining the hydrophobic segment M1, which corresponds to the fifth exon of the gamma-subunit gene. The two forms of gamma subunit coexist during myogenesis in vitro and in 17-day embryonic and denervated adult muscle fibers in vivo. However, the gamma s variant was the only form of gamma subunit in newborn muscle. In dissociated muscle fibers of newborn mice, AcCho-evoked channel openings were more prolonged when compared with C2C12 myotubes or denervated adult muscle fibers. The gamma s subunit may, thus, contribute to the structural and functional diversity of nAcChoRs in muscle cells.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

We analyze spectra of 18 stars belonging to the faintest subgiant branch in ωCentauri (the SGB-a), obtained with GIRAFFE@VLT at a resolution of R≃ 17   000 and a S/Nratio between 25 and 50. We measure abundances of Al, Ba, Ca, Fe, Ni, Si, and Ti and we find that these stars have  ⟨[Fe/H]⟩  =  −0.73 ± 0.14 dex, similarly to the corresponding red giant branch population (the RGB-a). We also measure  ⟨[α/Fe]⟩  =  + 0.40 ± 0.16 dex, and  ⟨[Ba/Fe]⟩  =  + 0.87 ± 0.23 dex, in general agreement with past studies. It is very interesting to note that we found a uniform Al abundance,  ⟨[Al/Fe]⟩  =  + 0.32 ± 0.14 dex, for all the 18 SGB-a stars analysed here, thus supporting past evidence that the usual (anti-)correlations are not present in this population, and suggesting a non globular cluster-like origin of this particular population. In the dwarf galaxy hypothesis for the formation of ωCen, this population might be the best candidate for the field population of its putative parent galaxy, although some of its properties appear contradictory. It has also been suggested that the most metal-rich population in ωCen is significantly enriched in helium. If this is true, the traditional abundance analysis techniques, based on model atmospheres with normal helium content, might lead to errors. We have computed helium enhanced atmospheres for three stars in our sample and verified that the abundance errors due to the use of non-enhanced atmospheres are negligible. Additional, indirect support to the enhanced helium content of the SGB-a population comes from our Li upper limits.

Context.Extremely metal-poor stars (EMP) are very rare objects that hold in their atmospheres the fossil record of the chemical composition of the early phases of Galactic evolution. Finding these objects and determining their chemical composition provides important constraints on these early phases.

Context.Lithium is a fragile element, which is easily destroyed in the stellar interior. The existence of lithium-rich giants still represents a challenge for stellar evolution models.

We analysed high-resolution UVES spectra of six stars belonging to the subgiant branch of ωCentauri, and derived abundance ratios of 19 chemical elements (namely Al, Ba, C, Ca, Co, Cr, Cu, Fe, La, Mg, Mn, N, Na, Ni, Sc, Si, Sr, Ti, and Y). A comparison with previous abundance determinations for red giants provided remarkable agreement and allowed us to identify the sub-populations to which our targets belong. We found that three targets belong to a low-metallicity population at [Fe/H]  ≃  –2.0 dex, [α/Fe]  ≃  +0.4 dex and [s/Fe]  ≃  0 dex. Stars with similar characteristics were found in small amounts by past surveys of red giants. We discuss the possibility that they belong to a separate sub-population that we name VMP (very metal-poor, at most 5% of the total cluster population), which – in the self-enrichment hypothesis – is the best-candidate first stellar generation in ωCen. Two of the remaining targets belong to the dominant metal-poor population (MP) at [Fe/H]  ≃  –1.7 dex, and the last one to the metal-intermediate (MInt) one at [Fe/H]  ≃  –1.2 dex. The existence of the newly defined VMP population could help to understand some puzzling results based on low-resolution spectroscopy for age differences determinations, because the metallicity resolution of these studies was probably not enough to detect the VMP population. The VMP could also correspond to some of the additional substructures of the subgiant-branch region found in the latest HST photometry. After trying to correlate chemical abundances with substructures in the subgiant branch of ωCen, we found that the age difference between the VMP and MP populations should be small (0  ±  2 Gyr), while the difference between the MP and MInt populations could be slightly larger (2  ±  2 Gyr).

Context.Palomar 1 is a peculiar globular cluster (GC). It is the youngest Galactic GC and it has been tentatively associated to several of the substructures recently discovered in the Milky Way (MW), including the Canis Major (CMa) overdensity and the Galactic Anticenter Stellar Structure (GASS).

Context. A discrepancy has emerged between the cosmic lithium abundance inferred by the WMAP satellite measurement coupled with the prediction of the standard big-bang nucleosynthesis theory, and the constant Li abundance measured in metal-poor halo dwarf stars (the so-called Spite plateau). Several models are being proposed to explain this discrepancy, involving either new physics, in situ depletion, or the efficient depletion of Li in the pristine Galaxy by a generation of massive first stars. The realm of possibilities may be narrowed considerably by observing stellar populations in different galaxies, which have experienced different evolutionary histories.Aims. The ωCentauri stellar system is commonly considered as the remnant of a dwarf galaxy accreted by the Milky Way. We investigate the lithium content of a conspicuous sample of unevolved stars in this object.Methods. We obtained moderate resolution (R= 17 000) spectra for 91 main-sequence/early sub-giant branch (MS/SGB) ωCen stars using the FLAMES-GIRAFFE/VLT spectrograph. Lithium abundances were derived by matching the equivalent width of the Li iresonance doublet at 6708 Å  to the prediction of synthetic spectra computed with different Li abundances. Synthetic spectra were computed using the SYNTHE code along with ATLAS–9 model atmospheres. The stars effective temperatures are derived by fitting the wings of the H$_\alpha$line with synthetic profiles.Results. We obtain a mean content of A(Li) = 2.19 ±0.14 dex for ωCentauri MS/SGB stars. This is comparable to what is observed in Galactic halo field stars of similar metallicities and temperatures.Conclusions. The Spite plateau seems to be an ubiquitous feature of old, warm metal-poor stars. It exists also in external galaxies, if we accept the current view about the origin of ωCen. This implies that the mechanism(s) that causes the “cosmological lithium problem” may be the same in the Milky Way and other galaxies.

Context. A discrepancy has emerged between the cosmic lithium abundance inferred by the WMAP satellite measurement coupled with the prediction of the standard big-bang nucleosynthesis theory, and the constant Li abundance measured in metal-poor halo dwarf stars (the so-called Spite plateau). Several models are being proposed to explain this discrepancy, involving either new physics, in situ depletion, or the efficient depletion of Li in the pristine Galaxy by a generation of massive first stars. The realm of possibilities may be narrowed considerably by observing stellar populations in different galaxies, which have experienced different evolutionary histories.

With now well established procedures for rapid chemical synthesis of oligodeoxyribonucleotides, these compounds have found widespread application in molecular biology research. In particular, the total synthesis of genes has become an attractive basis for the molecular design of proteins. Since synthetic genes have the advantage of being constructed from a set of short oligonucleotides (fragments), new gene variants can be generated conveniently by replacing some of the fragments.

CAFFEINE is one of the main constituents of the coffee bean. In spite of the existence of a limited but expanding market for decaffeinated coffee, most people still seem to prefer the normal product with caffeine. So important is the caffeine in coffee that Chevalier1separated all 18 coffee species of Madagascar and Mascarene Islands into a special section Mascarocoffea, on the basis of the presence, or absence, of caffeine. On the other hand, the Eucoffea section, which includes the cultivated coffee species, comprises only species with caffeine.