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The expected performance of stellar parametrization with Gaia spectrophotometry  [PDF]
C. Liu,C. A. L. Bailer-Jones,R. Sordo,A. Vallenari,R. Borrachero,X. Luri,P. Sartoretti
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.21797.x
Abstract: Gaia will obtain astrometry and spectrophotometry for essentially all sources in the sky down to a broad band magnitude limit of G=20, an expected yield of 10^9 stars. Its main scientific objective is to reveal the formation and evolution of our Galaxy through chemo-dynamical analysis. In addition to inferring positions, parallaxes and proper motions from the astrometry, we must also infer the astrophysical parameters of the stars from the spectrophotometry, the BP/RP spectrum. Here we investigate the performance of three different algorithms (SVM, ILIUM, Aeneas) for estimating the effective temperature, line-of-sight interstellar extinction, metallicity and surface gravity of A-M stars over a wide range of these parameters and over the full magnitude range Gaia will observe (G=6-20mag). One of the algorithms, Aeneas, infers the posterior probability density function over all parameters, and can optionally take into account the parallax and the Hertzsprung-Russell diagram to improve the estimates. For all algorithms the accuracy of estimation depends on G and on the value of the parameters themselves, so a broad summary of performance is only approximate. For stars at G=15 with less than two magnitudes extinction, we expect to be able to estimate Teff to within 1%, logg to 0.1-0.2dex, and [Fe/H] (for FGKM stars) to 0.1-0.2dex, just using the BP/RP spectrum (mean absolute error statistics are quoted). Performance degrades at larger extinctions, but not always by a large amount. Extinction can be estimated to an accuracy of 0.05-0.2mag for stars across the full parameter range with a priori unknown extinction between 0 and 10mag. Performance degrades at fainter magnitudes, but even at G=19 we can estimate logg to better than 0.2dex for all spectral types, and [Fe/H] to within 0.35dex for FGKM stars, for extinctions below 1mag.
GS-TEC: the Gaia Spectrophotometry Transient Events Classifier  [PDF]
Nadejda Blagorodnova,Sergey E. Koposov,?ukasz Wyrzykowski,Mike Irwin,Nicholas A. Walton
Physics , 2014, DOI: 10.1093/mnras/stu837
Abstract: We present an algorithm for classifying the nearby transient objects detected by the Gaia satellite. The algorithm will use the low-resolution spectra from the blue and red spectro-photometers on board of the satellite. Taking a Bayesian approach we model the spectra using the newly constructed reference spectral library and literature-driven priors. We find that for magnitudes brighter than 19 in Gaia $G$ magnitude, around 75\% of the transients will be robustly classified. The efficiency of the algorithm for SNe type I is higher than 80\% for magnitudes $G\leq$18, dropping to approximately 60\% at magnitude $G$=19. For SNe type II, the efficiency varies from 75 to 60\% for $G\leq$18, falling to 50\% at $G$=19. The purity of our classifier is around 95\% for SNe type I for all magnitudes. For SNe type II it is over 90\% for objects with $G \leq$19. GS-TEC also estimates the redshifts with errors of $\sigma_z \le$ 0.01 and epochs with uncertainties $\sigma_t \simeq$ 13 and 32 days for type SNe I and SNe II respectively. GS-TEC has been designed to be used on partially calibrated Gaia data. However, the concept could be extended to other kinds of low resolution spectra classification for ongoing surveys.
Intraosseous Lipoma of the Ilium
Halil üNALAN,Hilal SEVER,Javid MAJLESI,P?nar I?IK?
Trakya Universitesi Tip Fakultesi Dergisi , 2009,
Abstract: We report a case of intraosseous lipoma of the ilium which to the best of our knowledge, has a very rare incidence. Intraosseous lipoma of bone itself has an incidence of approximately 1/1000 among all bone tumors. The most commonly involved sites are metaphyseal or epiphyseal regions of long bones such as femur, tibia, fibula, and calcaneus. First case of intraosseous lipoma involving the ilium was reported in 1988 and although the exact incidence is not known, based on the literature survey, we can suggest that this bone still seems to be among the least commonly involved bones by this tumor in humans
Gaia  [PDF]
C. Cacciari,E. Pancino,M. Bellazzini
Physics , 2015,
Abstract: A review of the Gaia mission and its science performance after one year of operations will be presented, and the contribution to reconstructing the history of the Milky Way will be outlined.
An insight into the flux calibration of Gaia G-band images and BP/RP spectrophotometry  [PDF]
E. Pancino
Physics , 2010,
Abstract: The Gaia mission is described, focussing on those technical aspects that are necessary to understand the details of its external (absolute) flux calibration. On board of Gaia there will be two (spectro)photometers, the blue one (BP) and the red one (RP) covering the range 330-1050 nm, and the white light (G-band) imager dedicated to astrometry. Given the fact that the focal plane of Gaia will be constituted by 105 CCDs and the sources will cross the the focal plane at constant speed, at different positions in each of the foreseen passages (on average 70--80, but up to 350) in the mission lifetime, the ``simple" problem of calibrating the integrated BP/RP and G-band magnitudes and the low resolution BP/RP spectra flux turns into a very delicate and complicated issue, including CTI effects, LSF variations across the focal plane and with time, CCD gating to avoid saturation and the like. The calibration model requires a carefully selected set of $\simeq$200 SpectroPhotometric Standard Stars (SPSS) with a nominal precision of a few \%, with respect to Vega.
Quantitative determination of formaldehyde by spectrophotometry utilizing multivariate Curve resolution alternating least squares  [cached]
Mohammadreza Khanmohammadi,Nasser Dalali,Farshad Karami,Amir Bagheri Garmarudi
Bulletin of the Chemical Society of Ethiopia , 2012,
Abstract: Formaldehyde is a vastly used material in industry. Nowadays, it is proven that formaldehyde is toxic and carcinogenic. Thus providing a reliable method for its quantitative determination is very important. This study proposes a UV-Vis spectrophotometric based method for determination of formaldehyde. The method is based on reaction between the analyte and Fluoral P. Spectral changes during the time were mathematically analyzed using a chemometrics technique, called "multivariate curve resolution alternating least squares" (MCR-ALS). Data processing by this chemometrics technique enhanced the reliability of the UV-Vis spectrophotometry for quantitative analysis of formaldehyde in real samples.DOI: http://dx.doi.org/10.4314/bcse.v26i2.13
Quantitative determination of formaldehyde by spectrophotometry utilizing multivariate Curve resolution alternating least squares
Mohammadreza Khanmohammadi, Nasser Dalali, Farshad Karami, Amir Bagheri Garmarudi, Hossein Nemati
Bulletin of the Chemical Society of Ethiopia , 2012,
Abstract: Formaldehyde is a vastly used material in industry. Nowadays, it is proven that formaldehyde is toxic and carcinogenic. Thus providing a reliable method for its quantitative determination is very important. This study proposes a UV-Vis spectrophotometric based method for determination of formaldehyde. The method is based on reaction between the analyte and Fluoral P. Spectral changes during the time were mathematically analyzed using a chemometrics technique, called "multivariate curve resolution alternating least squares" (MCR-ALS). Data processing by this chemometrics technique enhanced the reliability of the UV-Vis spectrophotometry for quantitative analysis of formaldehyde in real samples. KEY WORDS: Formaldehyde, Fluoral P, UV-Visible, Multivariate curve resolution alternating least squares; Quantitative analysis Bull. Chem. Soc. Ethiop. 2012, 26(2), 299-304. DOI: http://dx.doi.org/10.4314/bcse.v26i2.13
Formaldehyde in Alcoholic Beverages: Large Chemical Survey Using Purpald Screening Followed by Chromotropic Acid Spectrophotometry with Multivariate Curve Resolution  [PDF]
Julien A. Jendral,Yulia B. Monakhova,Dirk W. Lachenmeier
International Journal of Analytical Chemistry , 2011, DOI: 10.1155/2011/797604
Abstract: A strategy for analyzing formaldehyde in beer, wine, spirits, and unrecorded alcohol was developed, and 508 samples from worldwide origin were analyzed. In the first step, samples are qualitatively screened using a simple colorimetric test with the purpald reagent, which is extremely sensitive for formaldehyde (detection limit 0.1?mg/L). 210 samples (41%) gave a positive purpald reaction. In the second step, formaldehyde in positive samples is confirmed by quantitative spectrophotometry of the chromotropic acid-formaldehyde derivative combined with Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). Calculation of UV-VIS and 13C NMR spectra confirmed the monocationic dibenzoxanthylium structure as the product of the reaction and disproved the widely cited para,para-quinoidal structure. Method validation for the spectrophotometric procedure showed a detection limit of 0.09 mg/L and a precision of 4.2–8.2% CV. In total, 132 samples (26%) contained formaldehyde with an average of 0.27?mg/L (range 0–14.4?mg/L). The highest incidence occurred in tequila (83%), Asian spirits (59%), grape marc (54%), and brandy (50%). Our survey showed that only 9 samples (1.8%) had formaldehyde levels above the WHO IPCS tolerable concentration of 2.6?mg/L. 1. Introduction The International Agency for Research on Cancer (IARC) has upgraded the cancer classification of formaldehyde in 2006 to now being clearly “carcinogenic to humans” (group 1) [1]. More recently, formaldehyde has been implicated by the IARC as a causative agent of leukemia as well as nasopharyngeal cancer in humans [2]. The US EPA provides a reference dose for chronic oral exposure (RfD) of 0.2?mg/kg bodyweight/day [3]. The WHO IPCS [4] has established a tolerable concentration (TC) of 2.6?mg/L in ingested products based on animal experiments [5]. Systematic data are currently lacking regarding the formaldehyde content of alcoholic beverages or indeed of most food in general. Feron et al. [6] estimated that the formaldehyde intake by food may range between 1.5 and 14?mg/person/day, which could, therefore, exceed the RfD in a worst case scenario. As we had previously conducted in-depth research into acetaldehyde content of alcoholic beverages [9, 10], we were recently asked if we had similar data on formaldehyde and if this compound may pose a risk to consumers in addition to the risk of ethanol [11]. We had no such data, because formaldehyde cannot be analyzed along with the other volatiles (e.g., acetaldehyde and methanol) during a typical gas chromatographic reference method [12]. For this
Mapping the stellar populations of the Milky Way with Gaia  [PDF]
Carla Cacciari
Physics , 2014, DOI: 10.1007/978-3-319-10993-0_18
Abstract: Gaia will be ESA's milestone astrometric mission, and is due for launch at the end of 2013. Gaia will repeatedly map the whole sky measuring about one billion sources to V=20-22 mag. Its data products will be {\mu}as accuracy astrometry, optical spectrophotometry and medium resolution spectroscopy. A description of the Gaia space mission and its characteristics and performance is given. The expected impact on Galactic stellar population studies is discussed, with particular attention to the sources of interest for CoRoT and Kepler.
Simultaneous determination and classification of riboflavin, thiamine, nicotinamide and pyridoxine in pharmaceutical formulations, by UV-visible spectrophotometry and multivariate analysis
López-de-Alba, Pedro L.;López-Martínez, Leticia;Cerdá, Vìctor;Amador-Hernández, Judith;
Journal of the Brazilian Chemical Society , 2006, DOI: 10.1590/S0103-50532006000400012
Abstract: soft independent modeling of class analogy and partial least squares regression were used in this work for the identification and quantification of thiamine, riboflavin, nicotinamide and pyridoxine by uv-vis spectrophotometry, without separation or preconcentration steps in the analytical procedure. for quantitative purposes, the working range established was 1-14 mg l-1 for riboflavin, 2-26 mg l-1 for thiamine, 2-30 mg l-1 for nicotinamide, and 2-22 mg l-1 for pyridoxine. recovery results higher than 95% were obtained in all cases during the analysis of synthetic and commercial samples. in the screening of each target vitamin, a classification model was built with two classes: (i) with the vitamin of interest, and (ii) without it. the discriminate capability of each classification model was evaluated for learning, independent testing and commercial samples, resulting in satisfactory findings with exception of riboflavin. thus, a simple and reliable method is proposed for the simultaneous estimation of these compounds.
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