Showing papers by "DSM published in 2003"
DSM1
TL;DR: In this article, a CdTe gamma-ray camera is operating in space for the first time in the history of high energy astronomy, and it shows no signs of degradation after 9 months in orbit.
Abstract: For the first time in the history of high energyastronomy, a large CdTe gamma-ray camera is operating in space. ISGRI is the low-energy camera of the IBIS telescope on board the INTEGRAL satellite. This paper details its design and itsin-flight behavior and performances. Having a sensitive area of 2621 cm$^2$ with a spatial resolution of 4.6 mm, a low threshold around 12 keV and an energy resolution of $\sim$ 8\% at 60 keV, ISGRI shows absolutely no signs of degradation after 9 months in orbit. All aspects of its in-flight behavior and scientific performance are fully nominal, and in particular the observedbackground level confirms the expected sensitivity of 1 milliCrab for a 10$^6$s observation.
848 citations
TL;DR: Expect many new industrial applications of biocatalysis to be realized, from single-step enzymatic conversions to customized multistep microbial synthesis by means of metabolic pathway engineering.
Abstract: Biocatalysis has emerged as an important tool in the industrial synthesis of bulk chemicals, pharmaceutical and agrochemical intermediates, active pharmaceuticals, and food ingredients. However, the number and diversity of the applications are modest, perhaps in part because of perceived or real limitations of biocatalysts, such as limited enzyme availability, substrate scope, and operational stability. Recent scientific breakthroughs in genomics, directed enzyme evolution, and the exploitation of biodiversity should help to overcome these limitations. As a result, we expect many new industrial applications of biocatalysis to be realized, from single-step enzymatic conversions to customized multistep microbial synthesis by means of metabolic pathway engineering.
775 citations
TL;DR: SPI as discussed by the authors is a high spectral resolution gamma-ray telescope on board the ESA mission INTEGRAL (International Gamma Ray Astrophysics Laboratory), which consists of an array of 19 closely packed germanium detectors surrounded by an active anticoincidence shield of BGO.
Abstract: SPI is a high spectral resolution gamma-ray telescope on board the ESA mission INTEGRAL (International Gamma Ray Astrophysics Laboratory). It consists of an array of 19 closely packed germanium detectors surrounded by an active anticoincidence shield of BGO. The imaging capabilities of the instrument are obtained with a tungsten coded aperture mask located 1.7 m from the Ge array. The fully coded field-of-view is 16degrees, the partially coded field of view amounts to 31degrees, and the angular resolution is 2.5degrees. The energy range extends from 20 keV to 8 MeV with a typical energy resolution of 2.5 keV at 1.3 MeV. Here we present the general concept of the instrument followed by a brief description of each of the main subsystems. INTEGRAL was successfully launched in October 2002 and SPI is functioning extremely well.
621 citations
TL;DR: In this paper, the authors observed a narrow state near 2.32 GeV/c(2) in the inclusive D(+)(s)pi(0) invariant mass distribution from e(+)e(-) annihilation data at energies near 10.6 GeV.
Abstract: We have observed a narrow state near 2.32 GeV/c(2) in the inclusive D(+)(s)pi(0) invariant mass distribution from e(+)e(-) annihilation data at energies near 10.6 GeV. The observed width is consistent with the experimental resolution. The small intrinsic width and the quantum numbers of the final state indicate that the decay violates isospin conservation. The state has natural spin-parity and the low mass suggests a J(P)=0(+) assignment. The data sample corresponds to an integrated luminosity of 91 fb(-1) recorded by the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) storage ring.
497 citations
DSM1
TL;DR: Ligand-free Pd(OAc)(2) can be used as a catalyst in the Heck reaction of aryl bromides as long as the amount of catalyst is kept between 0.01 and 0.1 mol %.
495 citations
TL;DR: A broad overview of the state of the art in this field, examining theoretical models for densely grafted polymers (brushes), experimental techniques for their preparation and the properties of the ensuing structures is presented.
370 citations
TL;DR: The specific transcriptional responses of Saccharomyces cerevisiaeto growth limitation by carbon, nitrogen, phosphorus, or sulfur were characterized and functional annotations of these genes indicated cellular metabolism was altered to meet the growth requirements for nutrient-limited growth.
361 citations
TL;DR: In this article, K-band imaging observations of ten gamma-ray burst (GRB) host galaxies for which an optical and/or radio afterglow associated with the GRB event was clearly identified.
Abstract: We present K-band imaging observations of ten gamma-ray burst (GRB) host galaxies for which an optical and/or radio afterglow associated with the GRB event was clearly identified. Data were obtained with the Very Large Telescope and New Technology Telescope at ESO (Chile), and with the Gemini-North telescope at Mauna Kea (Hawaii). Adding to our sample nine other GRB hosts with K-band photometry and determined redshifts published in the literature, we compare their observed and absolute K magnitudes as well as their R K colours with those of other distant sources detected in various optical, near- infrared, mid-infrared and submillimeter deep surveys. We find that the GRB host galaxies, most of them lying at 0:5< z< 1:5, exhibit very blue colours, comparable to those of the faint blue star-forming sources at high redshift. They are sub-luminous in the K-band, suggesting a low stellar mass content. We do not find any GRB hosts harbouring R -a ndK-band properties similar to those characterizing the luminous infrared/submillimeter sources and the extremely red starbursts. Should GRBs be regarded as an unbiased probe of star-forming activity, this lack of luminous and/or reddened objects among the GRB host sample might reveal that the detection of GRB optical afterglows is likely biased toward unobscured galaxies. It would moreover support the idea that a large fraction of the optically-dark GRBs occur within dust-enshrouded regions of star formation. On the other hand, our result might also simply reflect intrinsic properties of GRB host galaxies experiencing a first episode of very massive star formation and characterized by a rather weak underlying stellar population. Finally, we compute the absolute B magnitudes for the whole sample of GRB host galaxies with known redshifts and detected at optical wavelengths. We find that the latter appear statistically even less luminous than the faint blue sources which mostly contributed to the B-band light emitted at high redshift. This indicates that the formation of GRBs could be favoured in particular systems with very low luminosities and, therefore, low metallicities. Such an intrinsic bias toward metal-poor environments would be actually consistent with what can be expected from the currently-favoured scenario of the "collapsar". The forthcoming launch of the SWIFT mission at the end of 2003 will provide a dramatic increase of the number of GRB-selected sources. A detailed study of the chemical composition of the gas within this sample of galaxies will thus allow us to further analyse the potential eect of metallicity in the formation of GRB events.
308 citations
TL;DR: The coded-mask imaging gamma-ray telescope onboard the INTEGRAL satellite (IBIS) provides high-resolution (12') sky images of 29° x 29° in the energy range from 15 keV to 10 MeV with typical on-axis sensitivity of 1 mCrab at 100 keV (3σ, 10 6 s exposure).
Abstract: The gamma-ray astronomical observatory INTEGRAL, succesfully launched on 17th October 2002, carries two large gamma-ray telescopes. One of them is the coded-mask imaging gamma-ray telescope onboard the INTEGRAL satellite (IBIS) which provides high-resolution (12') sky images of 29° x 29° in the energy range from 15 keV to 10 MeV with typical on-axis sensitivity of 1 mCrab at 100 keV (3σ, 10 6 s exposure). We report here the general description of the IBIS coded-mask imaging system and of the standard IBIS science data analysis procedures. These procedures reconstruct, clean and combine IBIS sky images providing at the same time detection, identification and preliminary analysis of point-like sources present in the field. Spectral extraction has also been implemented and is based on simultaneous fitting of source and background shadowgram models to detector images. The procedures are illustrated using some of the IBIS data collected during the inflight calibrations and present performance is discussed. The analysis programs described here have been integrated as instrument specific software in the Integral Science Data Center (ISDC) analysis software packages currently used for the Quick Look, Standard and Off-line Scientific Analysis.
302 citations
DSM1
TL;DR: In this article, the authors present an industrial view on the current developments in the field of reactive separations, particularly reactive distillation, reactive adsorption and membrane reactors, and their place in the intensification of chemical manufacturing and processing.
Abstract: The paper presents an industrial view on the current developments in the field of reactive separations, particularly reactive distillation, reactive adsorption and membrane reactors, and their place in the intensification of chemical manufacturing and processing. Several cases of successfully commercialized reactive separation technologies are presented. Barriers hindering a wider introduction of reactive separations in the industry are discussed, together with the most likely scenarios of further developments in the field.
278 citations
DSM1
TL;DR: Not all cells withFLT3 ITD express significant amounts of the mutated receptor protein, signals downstream from wild-type and mutant FLT3 receptors are not 100% idential, and MV4-11 represents a model cell line for FLT 3 ITD signalling.
Abstract: Internal tandem duplications (ITD) and D835 point mutations of the receptor tyrosine kinase (RTK) FLT3 are found in a high proportion of cases with acute myeloid leukemia (AML). These genetic aberrations may lead to the constitutive activation of the receptor, thus providing the molecular basis for a persisting growth stimulus. We have screened 69 AML-derived cell lines for FLT3 mutations. Four of these cell lines showed ITD of the FLT3 gene, none carried a D835 point mutation. Two cell lines (MUTZ-11 and MV4-11) expressed exclusively the mutated allele, the other two cell lines (MOLM-13 and PL-21) displayed a mutated and the wild-type version of the gene. Although mutationally activated FLT3 is supposed to substitute for the stimulatory signal of a growth factor, one of these cell lines (MUTZ-11) was strictly cytokine-dependent. FLT3 transcripts were found in all four cell lines, but the constitutively phosphorylated receptor protein was clearly detectable only in cell line MV4-11, possibly explaining why MUTZ-11 cells were growth-factor dependent. Thus, not all FLT3 ITD-positive cells express high levels of the active receptor protein, a finding that might be of relevance for a possible future application of a kinase inhibitor as therapeutic agent. It had been described that STAT-5 phosphorylation was part of the FLT3 signalling chain and that STAT-5 molecules were constitutively phosphorylated in FLT3 ITD-positive cells. Although we observed the constitutive phosphorylation of STAT-5 molecules in FLT3-mutant cells, FLT3 ligand (FL) did not induce STAT-5 phosphorylation in FLT3 wild-type cells. These results suggest that the signalling mechanisms of the mutated FL receptor differ at least to some extent from those conferred by wild-type FLT3. In conclusion, (1) not all cells with FLT3 ITD express significant amounts of the mutated receptor protein; (2) signals downstream from wild-type and mutant FLT3 receptors are not 100% identical; and (3) MV4-11 represents a model cell line for FLT3 ITD signalling.
TL;DR: In this paper, the first measurements of the 511 keV line emission from the Galactic Centre (GC) region performed with the spectrometer SPI on the space observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory).
Abstract: We report the first measurements of the 511 keV line emission from the Galactic Centre (GC) region performed with the spectrometer SPI on the space observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory). Taking into account the range of spatial distribution models which are consistent with the data, we derive a flux of 9:9 +4:7 2:1 10 4 ph cm 2 s 1 and an intrinsic line width of 2:95 +0:45 0:51 keV (FWHM). The results are consistent with other high-spectroscopy measurements, though the width is found to be at the upper bound of previously reported values.
TL;DR: In this paper, the gamma-ray emission expected from the jet-wind hadronic interaction with high-mass stellar companions has been investigated and the detectability of the phenomenon at high energies has been discussed.
Abstract: The jets of microquasars with high-mass stellar companions are exposed to the dense matter field of the stellar wind. We present estimates of the gamma-ray emission expected from the jet-wind hadronic interaction and we discuss the detectability of the phenomenon at high energies. The proposed mechanism could explain some of the unidentified gamma-ray sources detected by EGRET instrument on the galactic plane.
Cardiff University1, University of Paris2, University of Paris-Sud3, University of Toulouse4, California Institute of Technology5, Jet Propulsion Laboratory6, Institut d'Astrophysique de Paris7, Sapienza University of Rome8, University of Oxford9, University of Grenoble10, University of Minnesota11, Maynooth University12, Landau Institute for Theoretical Physics13, DSM14
TL;DR: In this paper, the cosmological constraints that Archeops places on adiabatic cold dark matter models with passive power-law initial fluctuations were analyzed, and the spectral index n was measured to be 1.04 (+0.10, 0.12) when the optical depth to reionization, tau, is allowed to vary as a free parameter, and 0.96 (+ 0.03,0.04) when tau is fixed to zero, both in good agreement with inflation.
Abstract: We analyze the cosmological constraints that Archeops places on adiabatic cold dark matter models with passive power-law initial fluctuations. Because its angular power spectrum has small bins in l and large l coverage down to COBE scales, Archeops provides a precise determination of the first acoustic peak in terms of position at multipole l_peak=220 +- 6, height and width. An analysis of Archeops data in combination with other CMB datasets constrains the baryon content of the Universe, Omega(b)h^2 = 0.022 (+0.003,-0.004), compatible with Big-Bang nucleosynthesis and with a similar accuracy. Using cosmological priors obtainedfrom recent non-CMB data leads to yet tighter constraints on the total density, e.g. Omega(tot)=1.00 (+0.03,-0.02) using the HST determination of the Hubble constant. An excellent absolute calibration consistency is found between Archeops and other CMB experiments, as well as with the previously quoted best fit model.The spectral index n is measured to be 1.04 (+0.10,-0.12) when the optical depth to reionization, tau, is allowed to vary as a free parameter, and 0.96 (+0.03,-0.04) when tau is fixed to zero, both in good agreement with inflation.
01 Aug 2003
TL;DR: In this article, the authors reported the high S/N observation on October 3, 2002 with XMM-Newton of the brightest X-ray flare detected so far from Sgr A* with a duration shorter than one hour (∼ 2.7 ks).
Abstract: We report the high S/N observation on October 3, 2002 with XMM-Newton of the brightest X-ray flare detected so far from Sgr A* with a duration shorter than one hour (∼ 2.7 ks). The light curve is almost symmetrical with respect to the peak flare, and no significant difference between the soft and hard X-ray range is detected. The overall flare spectrum is well represented by an absorbed power-law with a soft photon spectral index of r = 2.5 ′ 0.3, and a peak 2-10 keV luminosity of 3.6 + 0 . 3 -0.4 × 10 3 5 erg s - 1 , i.e. a factor 160 higher than the Sgr A* quiescent value. No significant spectral change during the flare is observed. This X-ray flare is very different from other bright flares reported so far: it is much brighter and softer. The present accurate determination of the flare characteristics challenge the current interpretation of the physical processes occuring inside the very close environment of Sgr A* by bringing very strong constraints for the theoretical flare models.
TL;DR: In situ atomic force microscopy experiments are reported which reveal the presence of nanoscale damage cavities ahead of a stress-corrosion crack tip in glass, which might explain the departure from linear elasticity observed in the vicinity of a crack tip.
Abstract: We report in situ atomic force microscopy experiments which reveal the presence of nanoscale damage cavities ahead of a stress-corrosion crack tip in glass. Their presence might explain the departure from linear elasticity observed in the vicinity of a crack tip in glass. Such a ductile fracture mechanism, widely observed in the case of metallic materials at the micrometer scale, might be also at the origin of the striking similarity of the morphologies of fracture surfaces of glass and metallic alloys at different length scales.
DSM1
TL;DR: Engineering the uptake of carbon, the regulatory circuits, central metabolism and the common aromatic pathway including shikimic acid import that have all been targeted to effect higher productivities and lower by-product formation are discussed.
TL;DR: The coded-mask imaging gamma-ray telescope onboard the INTEGRAL satellite (IBIS) provides high-resolution sky images of 29deg x 29deg in the energy range from 15 keV to 10 MeV with typical on-axis sensitivity of 1 mCrab at 100 keV (3 sigma, 10E6 s exposure) as discussed by the authors.
Abstract: The gamma-ray astronomical observatory INTEGRAL, succesfully launched on 17th October 2002, carries two large gamma-ray telescopes. One of them is the coded-mask imaging gamma-ray telescope onboard the INTEGRAL satellite (IBIS) which provides high-resolution (~ 12') sky images of 29deg x 29deg in the energy range from 15 keV to 10 MeV with typical on-axis sensitivity of ~ 1 mCrab at 100 keV (3 sigma, 10E6 s exposure). We report here the general description of the IBIS coded-mask imaging system and of the standard IBIS science data analysis procedures. These procedures reconstruct, clean and combine IBIS sky images providing at the same time detection, identification and preliminary analysis of point-like sources present in the field. Spectral extraction has also been implemented and is based on simultaneous fitting of source and background shadowgram models to detector images. The procedures are illustrated using some of the IBIS data collected during the inflight calibrations and present performance is discussed. The analysis programs described here have been integrated as instrument specific software in the Integral Science Data Center (ISDC) analysis software packages currently used for the Quick Look, Standard and Off-line Scientific Analysis.
TL;DR: In reconstructed epidermis the content of linoleic acid in all three acylceramides fraction was significantly lower, which together with a lower content of free fatty acids may explain the differences between native and reconstructed tissue in stratum corneum lipid organization observed earlier by X-ray diffraction.
Cardiff University1, University of Paris2, University of Paris-Sud3, University of Toulouse4, California Institute of Technology5, Institut d'Astrophysique de Paris6, Sapienza University of Rome7, University of Oxford8, University of Grenoble9, University of Minnesota10, Maynooth University11, Landau Institute for Theoretical Physics12, DSM13
TL;DR: In this paper, the angular power spectrum of the cosmic microwave background anisotropy in 16 bins over the multipole range l=15-350 was determined by the Archeops experiment.
Abstract: We present a determination by the Archeops experiment of the angular power spectrum of the cosmic microwave background anisotropy in 16 bins over the multipole range l=15-350. Archeops was conceived as a precursor of the Planck HFI instrument by using the same optical design and the same technology for the detectors and their cooling. Archeops is a balloon-borne instrument consisting of a 1.5 m aperture diameter telescope and an array of 21 photometers maintained at ~100 mK that are operating in 4 frequency bands centered at 143, 217, 353 and 545 GHz. The data were taken during the Arctic night of February 7, 2002 after the instrument was launched by CNES from Esrange base (Sweden). The entire data cover ~ 30% of the sky.This first analysis was obtained with a small subset of the dataset using the most sensitive photometer in each CMB band (143 and 217 GHz) and 12.6% of the sky at galactic latitudes above 30 degrees where the foreground contamination is measured to be negligible. The large sky coverage and medium resolution (better than 15 arcminutes) provide for the first time a high signal-to-noise ratio determination of the power spectrum over angular scales that include both the first acoustic peak and scales probed by COBE/DMR. With a binning of Delta(l)=7 to 25 the error bars are dominated by sample variance for l below 200. A companion paper details the cosmological implications.
TL;DR: In this paper, the authors reported the high S/N observation on October 3, 2002 with XMM-Newton of the brightest X-ray flare detected so far from SgrA* with a duration shorter than one hour (~ 2.7 ks).
Abstract: We report the high S/N observation on October 3, 2002 with XMM-Newton of the brightest X-ray flare detected so far from SgrA* with a duration shorter than one hour (~ 2.7 ks). The light curve is almost symmetrical with respect to the peak flare, and no significant difference between the soft and hard X-ray range is detected. The overall flare spectrum is well represented by an absorbed power-law with a soft photon spectral index of Gamma=2.5+/-0.3, and a peak 2-10 keV luminosity of 3.6 (+0.3-0.4) x 10^35 erg/s, i.e. a factor 160 higher than the Sgr A* quiescent value. No significant spectral change during the flare is observed. This X-ray flare is very different from other bright flares reported so far: it is much brighter and softer. The present accurate determination of the flare characteristics challenge the current interpretation of the physical processes occuring inside the very close environment of SgrA* by bringing very strong constraints for the theoretical flare models.
Patent•
DSM1
TL;DR: In this paper, a nucleic acid sequence encoding eukaryotic xylose isomerases and xylulose kinases was obtained from an anaerobic yeast or a filamentous fungus.
Abstract: The present invention relates to host cells transformed with a nucleic acid sequence encoding a eukaryotic xylose isomerase obtainable from an anaerobic fungus. When expressed, the sequence encoding the xylose isomerase confers to the host cell the ability to convert xylose to xylulose which may be further metabolised by the host cell. Thus, the host cell is capable of growth on xylose as carbon source. The host cell preferably is a eukaryotic microorganism such as a yeast or a filamentous fungus. The invention further relates to processes for the production of fermentation products such as ethanol, in which a host cell of the invention uses xylose for growth and for the production of the fermentation product. The invention further relates to nucleic acid sequences encoding eukaryotic xylose isomerases and xylulose kinases as obtainable from anaerobic fungi.
TL;DR: Very high enantioselectivities were obtained with MonoPhos, the simplest member of this class, a ligand that is prepared in a single step from BINOL and HMPT, and this invention might well lead to a broader application of asymmetric olefin hydrogenation for the production of enantiopure amino acids and amines.
Abstract: Monodentate phosphoramidites based on BINOL or substituted BINOL are excellent ligands for the rhodium-catalysed asymmetric hydrogenation of olefins. Very high enantioselectivities were obtained with MonoPhos (7a) the simplest member of this class, a ligand that is prepared in a single step from BINOL and HMPT. Turnover numbers up to 6000 have been obtained in the hydrogenation of dehydroamino acid derivatives. Enantioselectivities in the hydrogenation of dehydroamino acids are solvent dependent; in non-protic solvents they range from 95 - 99%. Itaconic acid and its dimethyl ester could be hydrogenated with 96 and 94% e.e., respectively. Hydrogenation of aromatic enamides gave the corresponding acylated amines in 86 - 94% e.e. Several analogous phosphoramidite ligands have been prepared. Surprisingly, bidentate ligands gave poorer results, both in terms of rate as well as enantioselectivity. Taddol-based phosphoramidites led to poor e.e. and slow rates. Methyl substituents at the 3,3'-position of BINOL led to a sharply reduced rate and a somewhat lower enantioselectivity. Bromo substituents at the 6,6'-position led to a slightly reduced rate but little effect was seen on enantioselectivity. Use of octahydro-MonoPhos (11) gave results that were very similar to those obtained with 7a. ne rate of the reaction is dependent on the hydrogen pressure, however, the enantioselectivity is not affected. The rate of the dehydroamino acid hydrogenation also increases if the ligand to rhodium ratio is reduced from 2.2 to 1.5 or even to 1.0; yet, there is no deleterious effect on the enantioselectivity. Catalytic activity ceases with L/Rh=3 when dehydroamino acid derivatives were used as substrate. The reaction shows a positive non-linear effect, which confirms the presence of Rh-complexes with more than one ligand. Following the hydrogenation of methyl 2-acetamidocinnnamate with Rh(nbd)(2)BF(4)/7a by electrospray mass spectrometry showed the presence of several rhodium species. Notable are the presence of [Rh(7a)(3)(+) and [Rh(7a)](4)(+). There is at present insufficient evidence to conclude if the active catalytic species carries one or two ligands. In view of the low cost of MonoPhos this invention might well lead to a broader application of asymmetric olefin hydrogenation for the production of enantiopure amino acids and amines.
TL;DR: In this article, the authors present new mid-infrared spectroscopy of the emission from warm circumstellar dust grains in Herbig Ae/Be stars and find a correla- tion between the strength of the silicate feature and its shape.
Abstract: We present new mid-infrared spectroscopy of the emission from warm circumstellar dust grains in Herbig Ae/Be stars. Our survey significantly extends the sample that was studied by Bouwman et al. (2001). We find a correla- tion between the strength of the silicate feature and its shape. We interpret this as evidence for the removal of small (0.1m) grains from the disk surface while large (1-2m) grains persist. If the evolution of the grain size distribution is dominated by gravitational settling, large grains are expected to disappear first, on a timescale which is much shorter than the typical age of our programme stars. Our observations thus suggest a continuous replenishment of micron sized grains at the disk surface. If the grain replenishment is due to the dredge-up of dust from the disk interior, the mineralogy we observe is representative of the bulk composition of dust in these stars.
TL;DR: In this paper, the authors investigated the spatial distribution, and the properties and chemical composition of the dust orbiting HD100546, which is remarkably different from other isolated Herbig Ae/Be stars in both the strength of the mid-IR excess and the composition of circumstellar dust.
Abstract: the date of receipt and acceptance should be inserted later Abstract. We have investigated the spatial distribution, and the properties and chemical composition of the dust orbiting HD100546. This system is remarkably different from other isolated Herbig Ae/Be stars in both the strength of the mid-IR excess and the composition of the circumstellar dust. To explain spectral features and the amount of mid-IR dust emission the presence of a component of small (< 10 µm) grains radiating at ∼200 K is required, which is not seen in other well investigated Herbig Ae/Be systems. This additional component is inconsistent with a uniform flaring disk model. The fraction of intercepted stellar light that is absorbed and re-emitted in the mid-IR is so large (∼ 70%) that it requires the disk to be more 'puffed up' at about 10AU, where the grains have T ∼ 200 K. This may occur if a proto-Jupiter clears out a gap at this distance allowing direct stellar light to produce an extended rim at the far side of the gap. The other remarkable difference with other isolated Herbig Ae/Be systems is the presence of a much larger mass fraction of the crystalline silicate forsterite in the circumstellar dust. We find that the mass fraction of crystalline silicates in HD100546 increases with decreasing temperature, i.e. with larger radial distances from the central star. This distribution of crystalline dust is inconsistent with radial mixing models where the crystalline silicates are formed by thermal annealing above the glass temperature in the very inner parts of the disk, and are subsequently transported outwards and mixed with amorphous material. We speculate that the formation and spatial distribution of the crystalline dust may be linked to the formation of a proto-Jupiter in the disk around HD100546. Such a proto-Jupiter could gravitationally stir the disk leading to a collisional cascade of asteroidal sized objects producing small crystalline grains, or it could cause shocks by tidal interaction with the disk which might produce crystalline dust grains through flash heating. As shown by Malfait et al. (1998), the infrared spectrum of HD100546 is very similar to that of C/1995 O1 Hale-Bopp (Crovisier et al. 1997). Using an identical methodology, we have therefore also studied this solar system comet. Both objects have an almost identical grain composition, but with the important difference that the individual dust species in Hale-Bopp are in thermal contact with each other, while this is not the case in HD100546. This suggests that if similar processes leading to the dust composition as seen in HD100546 also occurred in our own solar system, that Hale-Bopp formed after the formation of one or more proto-gas giants.
DSM1
TL;DR: These findings provide a rationale for mandating the procurement of reputably sourced LL cell lines and their regular authentication thereafter and discuss the impact of cross-contamination on scientific research, the reluctance of scientists to address the problem, and possible solutions.
Abstract: Human leukemia–lymphoma (LL) cell lines represent an extremely important resource for research in a variety of fields and disciplines. As the cell lines are used as in vitro model systems in lieu of primary cell material, it is crucial that the cells in the culture flasks faithfully correspond to the purported objects of study. Obviously, proper authentication of cell line derivation and precise characterization are indispensable requirements to use as model systems. A number of studies has shown an unacceptable level of LL cell lines to be false. We present here the results of authenticating a comprehensively large sample (n = 550) of LL cell lines mainly by DNA fingerprinting and cytogenetic evaluation. Surprisingly, near-identical incidences (ca 15%) of false cell lines were observed among cell lines obtained directly from original investigators (59/395: 14.9%) and from secondary sources (23/155: 14.8%) implying that most cross-contamination is perpetrated by originators, presumably during establishment. By comparing our data with those published, we were further able to subclassify the false cell lines as (1) virtual: cross-contaminated with and unretrievably overgrown by other cell lines during initiation, never enjoying independent existence; (2) misidentified: cross-contaminated subsequent to establishment so that an original prototype may still exist; or (3) misclassified: unwittingly established from an unintended (often normal) cell type. Prolific classic leukemia cell lines were found to account for the majority of cross-contaminations, eg CCRF-CEM, HL-60, JURKAT, K-562 and U-937. We discuss the impact of cross-contaminations on scientific research, the reluctance of scientists to address the problem, and consider possible solutions. These findings provide a rationale for mandating the procurement of reputably sourced LL cell lines and their regular authentication thereafter.
TL;DR: In this paper, the SPI spectrometer was used for sky observation in the 20 keV-8 MeV energy range using 19 germanium detectors, which achieved a resolution of 2.5 keV at 1.1 MeV.
Abstract: The SPI instrument has been launched on-board the INTEGRAL observatory on October 17, 2002. SPI is a spectrometer devoted to the sky observation in the 20 keV-8 MeV energy range using 19 germanium detectors. The performance of the cryogenic system is nominal and allows to cool the 19 kg of germanium down to 85 K with a comfortable margin. The energy resolution of the whole camera is 2.5 keV at 1.1 MeV. This resolution degrades with time due to particle irradiation in space. We show that the annealing process allows the recovery of the initial performance. The anticoincidence shield works as expected, with a low threshold at 75 keV, reducing the GeD background by a factor of 20. The digital front-end electronics system allows the perfect alignement in time of all the signals as well as the optimisation of the dead time (12%). We demonstrate that SPI is able to map regions as complex as the galactic plane. The obtained spectrum of the Crab nebula validates the present version of our response matrix. The 3sigma sensitivity of the instrument at 1 MeV is 8x10(-7) ph cm(-2) s(-1) keV(-1) for the continuum and 3x10(-5) ph cm(-2) s(-1) for narrow lines.
TL;DR: In this article, the authors provide constraints on the morphology of the 511 keV line emission from the galactic center region on basis of data taken with the spectrometer SPI on the INTEGRAL gamma-ray observatory.
Abstract: We provide first constraints on the morphology of the 511 keV line emission from the galactic centre region on basis of data taken with the spectrometer SPI on the INTEGRAL gamma-ray observatory. The data suggest an azimuthally symmetric galactic bulge component with FWHMof 9 with a 2 uncertainty range covering 6 18. The 511 keV line flux in the bulge component amounts to 9:9 +4:7
DSM1
TL;DR: The extent and efficiency of charge transfer is discussed as a function of sequence dependent energetics, of temperature dependent base-base couplings, and in relation with experiments.
Abstract: We report on coherent charge transport studies in periodic Poly(dG)-Poly(dC) and aperiodic lambda-phage DNA sequences. The extent and efficiency of charge transfer is discussed as a function of sequence dependent energetics, of temperature dependent base-base couplings, and in relation with experiments.
TL;DR: Investigation of microbial biodiversity and its physiological potential in formation waters of the Samotlor high-temperature oil reservoir (Western Siberia, Russia) revealed the presence of several groups of microorganisms that escaped cultivation, suggesting that their distribution may be much wider than suspected.
Abstract: Activity measurements by radioisotopic methods and cultural and molecular approaches were used in parallel to investigate the microbial biodiversity and its physiological potential in formation waters of the Samotlor high-temperature oil reservoir (Western Siberia, Russia). Sulfate reduction with rates not exceeding 20 nmol of H(2)S liter(-1) day(-1) occurred at 60 and 80 degrees C. In upper horizons (AB, A, and B), methanogenesis (lithotrophic and/or acetoclastic) was detected only in wells in which sulfate reduction did not occur. In some of the wells from deeper (J) horizons, high-temperature sulfate reduction and methanogenesis occurred simultaneously, the rate of lithotrophic methanogenesis exceeding 80 nmol of CH(4) liter(-1) day(-1). Enrichment cultures indicated the presence of diverse physiological groups representing aerobic and anaerobic thermophiles and hyperthermophiles; fermentative organotrophs were predominant. Phylogenetic analyses of 15 isolates identified representatives of the genera Thermotoga, Thermoanaerobacter, Geobacillus, Petrotoga, Thermosipho, and Thermococcus, the latter four being represented by new species. Except for Thermosipho, the isolates were members of genera recovered earlier from similar habitats. DNA obtained from three samples was hybridized with a set of oligonucleotide probes targeting selected microbial groups encompassing key genera of thermophilic bacteria and archaea. Oligonucleotide microchip analyses confirmed the cultural data but also revealed the presence of several groups of microorganisms that escaped cultivation, among them representatives of the Aquificales/Desulfurobacterium-Thermovibrio cluster and of the genera Desulfurococcus and Thermus, up to now unknown in this habitat. The unexpected presence of these organisms suggests that their distribution may be much wider than suspected.