Quantifying goodness of story narratives

In the present study an additional measure of story narrative performance, story completeness, is evaluated. The completeness measure involves a tally of the critical story components mentioned by a storyteller. It was hypothesized that by combining organizational (story grammar) and completeness measures, story “goodness” could be quantified. Data from 46 normal adults indicated that this analysis was relatively sensitive in that it classified the story narratives of the group into four distinct categories of story “goodness”. This analysis should prove useful for the study of narrative discourse of brain-injured populations

Quantifying goodness of story narratives

In the present study an additional measure of story narrative performance, story completeness, is evaluated. The completeness measure involves a tally of the critical story components mentioned by a storyteller. It was hypothesized that by combining organizational (story grammar) and completeness measures, story “goodness” could be quantified. Data from 46 normal adults indicated that this analysis was relatively sensitive in that it classified the story narratives of the group into four distinct categories of story “goodness”. This analysis should prove useful for the study of narrative discourse of brain-injured populations

MICRO PHOTO IONIZATION DETECTOR FOR VOLATILE ORGANIC COMPOUNDS

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MICRO PHOTO IONIZATION DETECTOR FOR BTEX ANALYSIS: REVIEW REPORT OF PERFORMANCE INFLUENCING PARAMETERS

International audienceVolatile Organic Compounds (VOCs) are gaseous chemical species emitted from solids and liquids that may cause short and long term adverse health effects. They are present in both outdoor and indoor air. In open environments, automotive exhausts and industrial waste are major sources of VOCs. They are also emitted from building materials, varnishes, paints, solvents, etc. [1]. Within the VOCs, BTEX (benzene, toluene, ethylbenzene, xylenes) are of greatest concern due to their health effects. Benzene, for example, is highly carcinogenic and the World Health Organization reports no safe level of exposure [2]. Gas chromatographs (GC) monitor air quality and can detect VOCs, these equipment are heavy, lab-based and non-portable. In 2016, Nasreddine [3] reported a miniaturized gas analyzer that can detect BTEX at ppb levels and weights 4 kg. In order to further reduce the size of this equipment and the consumption of carrier gas, its main components must be miniaturized and operate under low gas flow rate. The detector is one of the main components of the gas chromatograph, responsible for quantifying the chemicals sampled. This paper is centered on the type of detector named photo ionization detector (PID). The objective of this work is to present the main factors that affect the analytical PID performance. The information summarized here should be used as guidelines to design a future micro PID.Fig. 1 shows the basic elements of a photo ionization detector. In this device, a gas sample containing the chemicals flows through the ionization chamber, where photons emitted by the ionization source (UV lamp and window) reach the sample molecules. As a general rule, if the ionization energy of the photon is greater than the ionization potential of the molecule, ionization occurs. The electrodes establish then an electric field in the ionization chamber where the ionized molecules generate an ionization current proportional to the concentration of molecules in the gas sample.The performance of the PID is affected by design choices at the ionization source, ionization chamberand electrodes. The ionization source is selected according to the desired photon energy output,considering the target compounds to be detected. In theory, an ionization source with energy greater orequal to 9.3 ionizes all the BTEX molecules. However, Driscoll and Duffy [4] suggests to use the 10.2eV ionization source since it has the highest photon flux resulting in high PID sensitivity. The ionizationchamber should ensure uniform flow, otherwise the sensitivity of the PID is reduced [5]. Besides that,the ionization chamber volume should be as low as possible to reduce response time, thereby increasingsensitivity. A small volume also avoids remixing of organic species that have been previously separatedin the gas chromatograph and ensures uniform ionization of the sample, contributing positively to thelinearity and sensitivity of the signal. The electrodes inside the ionization chamber directly influencethe ion collection efficiency, which affects the sensitivity of the PID. Important electrode design aspectsinfluencing the ions collection efficiency are the electric field in the ionization chamber, the area of theelectrodes and the position of the electrodes in the ionization chamber [5].Micro and nanofabrication techniques can be used to miniaturize the PID with the possibility to improveits performance [5,6]. In the future, a micro PID design will be proposed and the most suitable microand nanofabrication technique for its fabrication will be evaluated. The new design will be based on themajor guidelines presented in this work with focus in diminishing both the ionization chamber volumeand the associated gas flow rate while maintaining low detection limit. The prototype will be evaluatedand compared to commercial PIDs

Differential stellar population models: how to reliably measure [Fe/H] and [alpha/Fe] in galaxies

We present differential stellar population models, which allow improved determinations of the ages, iron and alpha-element abundances of old stellar populations from spectral fitting. These new models are calibrated at solar abundances using the predictions from classical, semi-empirical stellar population models. We then use the predictive power of fully synthetic models to compute predictions for different [Fe/H] and [alpha/Fe]. We show that these new differential models provide remarkably accurate fits to the integrated optical spectra of the bulge globular clusters NGC6528 and NGC6553, and that the inferred [Fe/H] and [alpha/Fe] agree with values derived elsewhere from stellar photometry and spectroscopy. The analysis of a small sample of SDSS early-type galaxies further confirms that our alpha-enhanced models provide a better fit to the spectra of massive ellipticals than the solar-scaled ones. Our approach opens new opportunities for precision measurements of abundance ratios in galaxies.Comment: 5 pages, 5 figures, MNRAS in pres

Structure determination of Split-soret Cytochrome from a Desulfovibrio species isolated from a human abdominal abcess

The determined structure of the split-soret cytochrome (SSC) isolated from Desulfovibrio desulfuricans ATCC 27774 (D.d.) revealed a new Heme arrangement, which suggests that this protein constitutes a new cytochrome class.. SSC is a 52.6kDa homodimer containing four hemes at one end of the molecule. In each monomer the two hemes have their edges overlapped within van der Waals contacts. The polypeptide chain of each monomer supplies the sixth ligand to the heme-iron of the other monomer. A similar protein was recently purified from a homologous Desulfovibrio clinical strain isolated from an abdominal wall abscess in human patient2. Crystals of this SSC were grown using vapour diffusion method in the presence of agarose gel. Diffraction data were collected using X-ray synchrotron radiation at the ESRF, beamline, ID 14-1. The structure will be solved by molecular replacement using the structure of the D.d. as a starting model

MICROFLUIDIC PHOTOIONIZATION DETECTOR: CHANNEL GEOMETRY AND SIGNAL EVALUATION

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Challenges in Stellar Population Studies

The stellar populations of galaxies contain a wealth of detailed information. From the youngest, most massive stars, to almost invisible remnants, the history of star formation is encoded in the stars that make up a galaxy. Extracting some, or all, of this informationhas long been a goal of stellar population studies. This was achieved in the last couple of decades and it is now a routine task, which forms a crucial ingredient in much of observational galaxy evolution, from our Galaxy out to the most distant systems found. In many of these domains we are now limited not by sample size, but by systematic uncertainties and this will increasingly be the case in the future. The aim of this review is to outline the challenges faced by stellar population studies in the coming decade within the context of upcoming observational facilities. I will highlight the need to better understand the near-IR spectral range and outline the difficulties presented by less well understood phases of stellar evolution such as thermally pulsing AGB stars, horizontal branch stars and the very first stars. The influence of rotation and binarity on stellar population modeling is also briefly discussed.Comment: Plenary review talk at IAU GA in Rio de Janeiro to be published in the proceedings of IAU Symposium 262. Movies and talk slides available at http://www.strw.leidenuniv.nl/~jarle/IAU0

Modeling the color evolution of luminous red galaxies - improvements with empirical stellar spectra

Predicting the colors of Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS) has been a long-standing problem. The g,r,i colors of LRGs are inconsistent with stellar population models over the redshift range 0.1<z<0.7. The g-r colors in the models are on average redder than the data while the r-i colors in the models are bluer towards low redshift. Beyond redshift 0.4, the predicted r-i color becomes instead too red, while the predicted g-r agrees with the data. We provide a solution to this problem, through a combination of new astrophysics and a fundamental change to the stellar population modeling. We find that the use of the empirical library of Pickles (1998) instead of theoretical spectra modifies the predicted colors exactly in the way suggested by the data. The reason is a lower flux in the empirical libraries, with respect to the theoretical ones, in the wavelength range 5500-6500 AA. The discrepancy increases with decreasing effective temperature independently of gravity. This result has general implications for a variety of studies from globular clusters to high-redshift galaxies. The astrophysical part of our solution regards the composition of the stellar populations of these massive Luminous Red Galaxies. We find that on top of the previous effect one needs to consider a model in which ~3% of the stellar mass is in old metal-poor stars. Other solutions such as substantial blue Horizontal Branch at high metallicity or young stellar populations can be ruled out by the data. Our new model provides a better fit to the g-r and r-i colors of LRGs and gives new insight into the formation histories of these most massive galaxies. Our model will also improve the k- and evolutionary corrections for LRGs which are critical for fully exploiting present and future galaxy surveys.Comment: Submitted to ApJ Letters. High resolution version available at http://www.maraston.eu/Maraston_etal_2008.pd

Bridging Model and Observed Stellar Spectra

Accurate model stellar fluxes are key for the analysis of observations of individual stars or stellar populations. Model spectra differ from real stellar spectra due to limitations of the input physical data and adopted simplifications, but can be empirically calibrated to maximise their resemblance to actual stellar spectra. I describe a least-squares procedure of general use and test it on the MILES library.Comment: 7 pages, 6 figures, accepted for publication in MNRA