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Artykuły w czasopismach na temat „Fractional Abundances”

Autor: Grafiati

Data publikacji: 5 czerwca 2025

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1

Patterson, R. Timothy, and Evan Fishbein. "Re-examination of the statistical methods used to determine the number of point counts needed for micropaleontological quantitative research." Journal of Paleontology 63, no. 2 (1989): 245–48. http://dx.doi.org/10.1017/s0022336000019272.

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Currently some controversy exists in the micropaleontological community concerning the statistically correct number of counts required for quantitative examinations, particularly with respect to the effect of variations in the number of species between samples and the significance of varying fractional abundances on the reliability of results. This analysis of the various statistical methods used to determine the number of required counts has shown that the number of species has no relationship to the number of counts required to measure accurately fractional abundances. As part of the study,

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2

Koirala, Bikram, Mahdi Khodadadzadeh, Cecilia Contreras, Zohreh Zahiri, Richard Gloaguen, and Paul Scheunders. "A Supervised Method for Nonlinear Hyperspectral Unmixing." Remote Sensing 11, no. 20 (2019): 2458. http://dx.doi.org/10.3390/rs11202458.

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Due to the complex interaction of light with the Earth’s surface, reflectance spectra can be described as highly nonlinear mixtures of the reflectances of the material constituents occurring in a given resolution cell of hyperspectral data. Our aim is to estimate the fractional abundance maps of the materials from the nonlinear hyperspectral data. The main disadvantage of using nonlinear mixing models is that the model parameters are not properly interpretable in terms of fractional abundances. Moreover, not all spectra of a hyperspectral dataset necessarily follow the same particular mixing m

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3

Harada, Nanase, Sergio Martín, Jeffrey G. Mangum, et al. "ALCHEMI Finds a “Shocking” Carbon Footprint in the Starburst Galaxy NGC 253." Astrophysical Journal 938, no. 1 (2022): 80. http://dx.doi.org/10.3847/1538-4357/ac8dfc.

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Abstract The centers of starburst galaxies may be characterized by a specific gas and ice chemistry due to their gas dynamics and the presence of various ice desorption mechanisms. This may result in a peculiar observable composition. We analyse the abundances of CO2, a reliable tracer of ice chemistry, from data collected as part of the Atacama Large Millimeter/submillimeter Array large program ALCHEMI, a wide-frequency spectral scan toward the starburst galaxy NGC 253 with an angular resolution of 1.″6. We constrain the CO2 abundances in the gas phase using its protonated form HOCO+. The dis

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4

Kishor.P., Kadam. "Investigation of the Emission of Ionic Species." 'Journal of Research & Development' 14, no. 7 (2023): 105–10. https://doi.org/10.5281/zenodo.7810289.

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Ionization rate coefficients, recombination rate coefficients, electron impact excitation coefficients and fractional abundances of the different ionic species of the elements have been investigated. We have computed the radiative as well as dielectronic recombination and total recombination rate coefficients of Cu II, Cu III and Cu IV as a function of electron temperature. We obtained the fractional abundances of the elements like Cu, Zn, Li, Na, K, and Mg as a function of electron temperature. The computations show that the fractional abundance of the species changes as the electron temperat

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5

Notsu, Shota, Ewine F. van Dishoeck, Catherine Walsh, Arthur D. Bosman, and Hideko Nomura. "X-ray-induced chemistry of water and related molecules in low-mass protostellar envelopes." Astronomy & Astrophysics 650 (June 2021): A180. http://dx.doi.org/10.1051/0004-6361/202140667.

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Context. Water is a key molecule in star- and planet-forming regions. Recent water line observations toward several low-mass protostars suggest low water gas fractional abundances (<10−6 with respect to total hydrogen density) in the inner warm envelopes (r < 102 au). Water destruction by X-rays is thought to influence the water abundances in these regions, but the detailed chemistry, including the nature of alternative oxygen carriers, is not yet understood. Aims. Our aim is to understand the impact of X-rays on the composition of low-mass protostellar envelopes, focusing specifically o

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6

Massalkhi, S., M. Agúndez, J. Cernicharo, and L. Velilla-Prieto. "The abundance of S- and Si-bearing molecules in O-rich circumstellar envelopes of AGB stars." Astronomy & Astrophysics 641 (September 2020): A57. http://dx.doi.org/10.1051/0004-6361/202037900.

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Aims. We aim to determine the abundances of SiO, CS, SiS, SO, and SO2 in a large sample of oxygen-rich asymptotic giant branch (AGB) envelopes covering a wide range of mass loss rates to investigate the potential role that these molecules could play in the formation of dust in these environments. Methods. We surveyed a sample of 30 oxygen-rich AGB stars in the λ 2 mm band using the IRAM 30m telescope. We performed excitation and radiative transfer calculations based on the large velocity gradient method to model the observed lines of the molecules and to derive their fractional abundances in t

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7

Cavalli, Rosa Maria. "Spatial Validation of Spectral Unmixing Results: A Case Study of Venice City." Remote Sensing 14, no. 20 (2022): 5165. http://dx.doi.org/10.3390/rs14205165.

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Since remote sensing images offer unique access to the distribution of land cover on earth, many countries are investing in this technique to monitor urban sprawl. For this purpose, the most widely used methodology is spectral unmixing which, after identifying the spectra of the mixed-pixel constituents, determines their fractional abundances in the pixel. However, the literature highlights shortcomings in spatial validation due to the lack of detailed ground truth knowledge and proposes five key requirements for accurate reference fractional abundance maps: they should cover most of the area,

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8

Minh, Y. C., W. M. Irvine, and P. Friberg. "Molecular Abundances in the Sgr a Molecular Cloud." Symposium - International Astronomical Union 150 (1992): 223–24. http://dx.doi.org/10.1017/s0074180900090057.

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We have obtained column densities for HCO+, HCO, HCS+, C3H2, HC5N, SiO, OCS, HCOOH, CH3CH2 OH, and CH3CCH toward Sgr A. The fractional abundance of SiO relative to molecular hydrogen in Sgr A is comparable to that for the Orion plateau, ~ 10−7 − 10−8, which may be a typical value for hot clouds. The abundances of HCO, CH3CH2OH and CH3CCH all appear to be enhanced relative to other molecular clouds suc as Sgr B2.

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9

Massalkhi, S., M. Agúndez, and J. Cernicharo. "Study of CS, SiO, and SiS abundances in carbon star envelopes: assessing their role as gas-phase precursors of dust." Astronomy & Astrophysics 628 (August 2019): A62. http://dx.doi.org/10.1051/0004-6361/201935069.

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Aims. We aim to determine the abundances of CS, SiO, and SiS in a large sample of carbon star envelopes covering a wide range of mass loss rates to investigate the potential role that these molecules could play in the formation of dust in the surroundings of the central AGB star. Methods. We surveyed a sample of 25 carbon-rich AGB stars in the λ 2 mm band, more concretely in the J = 3−2 line of CS and SiO, and in the J = 7−6 and J = 8−7 lines of SiS, using the IRAM 30 m telescope. We performed excitation and radiative transfer calculations based on the large velocity gradient (LVG) method to m

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10

Bernhardt, V., A. Grumpe, and C. Wöhler. "SPECTRAL UNMIXING BASED CONSTRUCTION OF LUNAR MINERAL ABUNDANCE MAPS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W1 (July 25, 2017): 7–14. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w1-7-2017.

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In this study we apply a nonlinear spectral unmixing algorithm to a nearly global lunar spectral reflectance mosaic derived from hyper-spectral image data acquired by the Moon Mineralogy Mapper (M<sup>3</sup>) instrument. Corrections for topographic effects and for thermal emission were performed. A set of 19 laboratory-based reflectance spectra of lunar samples published by the Lunar Soil Characterization Consortium (LSCC) were used as a catalog of potential endmember spectra. For a given spectrum, the multi-population population-based incremental learning (MPBIL) algorithm was us

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11

Chi, Junhwa, and Hyun-Cheol Kim. "FORECASTING ANTARCTIC SEA ICE CONCENTRATIONS USING RESULTS OF TEMPORAL MIXTURE ANALYSIS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (June 23, 2016): 459–62. http://dx.doi.org/10.5194/isprs-archives-xli-b8-459-2016.

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Sea ice concentration (SIC) data acquired by passive microwave sensors at daily temporal frequencies over extended areas provide seasonal characteristics of sea ice dynamics and play a key role as an indicator of global climate trends; however, it is typically challenging to study long-term time series. Of the various advanced remote sensing techniques that address this issue, temporal mixture analysis (TMA) methods are often used to investigate the temporal characteristics of environmental factors, including SICs in the case of the present study. This study aims to forecast daily SICs for one

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12

Chi, Junhwa, and Hyun-Cheol Kim. "FORECASTING ANTARCTIC SEA ICE CONCENTRATIONS USING RESULTS OF TEMPORAL MIXTURE ANALYSIS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (June 23, 2016): 459–62. http://dx.doi.org/10.5194/isprsarchives-xli-b8-459-2016.

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Sea ice concentration (SIC) data acquired by passive microwave sensors at daily temporal frequencies over extended areas provide seasonal characteristics of sea ice dynamics and play a key role as an indicator of global climate trends; however, it is typically challenging to study long-term time series. Of the various advanced remote sensing techniques that address this issue, temporal mixture analysis (TMA) methods are often used to investigate the temporal characteristics of environmental factors, including SICs in the case of the present study. This study aims to forecast daily SICs for one

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13

Lodders, Katharina, and Bruce Fegley. "Condensation Chemistry of Circumstellar Grains." Symposium - International Astronomical Union 191 (1999): 279–90. http://dx.doi.org/10.1017/s0074180900203185.

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Thermochemical equilibrium calculations are successful in predicting the mineralogy as well as the major and trace element chemistry of circumstellar grains found in meteorites. The calculations also explain observations of dust close to AGB stars (within 1–3 stellar radii). The trace element chemistry in circumstellar graphite, SiC, and other refractory carbide grains agrees with equilibrium condensation calculations for circumstellar shells of carbon stars. Observed trace element abundance patterns in N stars are complementary to those found in SiC grains indicating fractional condensation i

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14

Abdel-Salam, Emad A. B., Mohamed I. Nouh, Yosry A. Azzam, and M. S. Jazmati. "Conformable Fractional Models of the Stellar Helium Burning via Artificial Neural Networks." Advances in Astronomy 2021 (March 16, 2021): 1–18. http://dx.doi.org/10.1155/2021/6662217.

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The helium burning phase represents the second stage that the star used to consume nuclear fuel in its interior. In this stage, the three elements, carbon, oxygen, and neon, are synthesized. The present paper is twofold: firstly, it develops an analytical solution to the system of the conformable fractional differential equations of the helium burning network, where we used, for this purpose, the series expansion method and obtained recurrence relations for the product abundances, that is, helium, carbon, oxygen, and neon. Using four different initial abundances, we calculated 44 gas models co

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15

Vargas, Hector, Ariolfo Camacho Velasco, and Henry Arguello. "Spectral unmixing approach in hyperspectral remote sensing: a tool for oil palm mapping." TecnoLógicas 22, no. 45 (2019): 129–43. http://dx.doi.org/10.22430/22565337.1228.

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Oil palm plantations typically span large areas; therefore, remote sensing has become a useful tool for advanced oil palm monitoring. This work reviews and evaluates two approaches to analyze oil palm plantations based on hyperspectral remote sensing data: linear spectral unmixing and spectral variability. Moreover, a computational framework based on spectral unmixing for the estimation of fractional abundances of oil palm plantations is proposed in this study. Such approach also considers the spectral variability of hyperspectral image signatures. More specifically, the proposed computational

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16

Feng, Yanan, Xiaohu Li, Xiaofeng Yang, et al. "Observations of Molecular CN toward S-type Asymptotic Giant Branch Stars." Astronomical Journal 168, no. 6 (2024): 285. http://dx.doi.org/10.3847/1538-3881/ad8ba6.

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Abstract S-type asymptotic giant branch (AGB) stars are defined by their carbon-to-oxygen (C/O) ratio approaching unity. However, observations of circumstellar molecules in these stars are limited and challenging. In this study, we used the James Clerk Maxwell Telescope to search for cyanide (CN) in 12 selected S-type AGB stars, with only 4 of these stars displaying CN spectral line signals. The column density and fractional abundance of CN were calculated assuming local thermodynamic equilibrium, and the average CN-to-hydrogen-cyanide (HCN) abundance ratio of the four sources is about 0.036.

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17

Sutton, Edmund C., and Andrej M. Sobolev. "Abundances of Organic Molecules in Molecular Cloud Cores." Symposium - International Astronomical Union 213 (2004): 173–76. http://dx.doi.org/10.1017/s0074180900193210.

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Molecular cloud cores are often found to contain regions with high abundances of organic molecules such as formaldehyde, methanol, ethanol, dimethyl ether, and methyl formate. First we will review the status of observations of these molecules in a number of sources and discuss some of the limitations of present techniques. Then we will discuss systematic factors involved in the conversion of column densities into fractional abundances and introduce an independent method of calibrating that conversion. Finally we will present recent results from high spatial resolution observations of W3(OH).

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18

Riquelme, D., M. A. Amo-Baladrón, J. Martín-Pintado, et al. "Footpoints of the giant molecular loops in the Galactic center region." Astronomy & Astrophysics 613 (May 2018): A42. http://dx.doi.org/10.1051/0004-6361/201629065.

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Aims. We aim to reveal the morphology, chemical composition, kinematics, and to establish the main processes prevalent in the gas at the footpoints of the giant molecular loops (GMLs) in the Galactic center region. Methods. Using the 22-m Mopra telescope, we mapped the M−3.8+0.9 molecular cloud, placed at the footpoints of a GML, in 3-mm range molecular lines. To derive the molecular hydrogen column density, we also observed the 13CO(2 − 1) line at 1 mm using the 12-m APEX telescope. From the 3 mm observations 12 molecular species were detected, namely HCO+, HCN, H13CN, HNC, SiO, CS, CH3OH, N2

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19

Taft, Sarah H., Robert D. Gehrz, Charles E. Woodward, Nathan Smith, Isabelle Perron, and Annalisa Citro. "Simulating Chemical Abundances in the Circumstellar Nebula of the Late Stage Binary RY Scuti." Astronomical Journal 169, no. 5 (2025): 271. https://doi.org/10.3847/1538-3881/adc251.

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Abstract RY Scuti, thought to be a Wolf–Rayet (WR) progenitor, is a massive post-main-sequence binary star system undergoing Roche-lobe overflow (RLOF). SOFIA (+FORCAST) spectroscopy of the inner, ionized region of RY Scuti’s double ringed toroidal nebula affirms the previous detection of the well-studied 12.81 μm Ne ii forbidden transition and reveals four distinct emission lines, including three previously undetected transitions, S iii, Fe iii, and S iii. Cloudy photoionization modeling of the four neon, sulfur, and iron lines was performed to derive fractional abundances (log( X H )) of neo

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20

Lu, Huimin, Ying Li, and Bingxin Liu. "Energy-Based Unmixing Method for Low Background Concentration Oil Spills at Sea." Remote Sensing 15, no. 8 (2023): 2079. http://dx.doi.org/10.3390/rs15082079.

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Marine oil spills have caused severe environmental pollution with long-term toxic effects on marine ecosystems and coastal habitants. Hyperspectral remote sensing is currently used in efforts to respond to oil spills. Spectral unmixing plays a key role in hyperspectral imaging because of its ability to extract accurate fractional abundances of constituent materials from spectrums collected by sensors. However, multiple oil-propagating processes provide different mixing states of oil and water, thereby involving complicated, nonlinear mixing effects between in-depth elements in water, especiall

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21

Zhi, Yuyou, Tiantian Guo, Jiachun Shi, Lingzao Zeng, and Laosheng Wu. "Expressing lead isotopic compositions by fractional abundances for environmental source apportionment." Environmental Pollution 218 (November 2016): 446–52. http://dx.doi.org/10.1016/j.envpol.2016.07.024.

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Feng, Ruyi, Lizhe Wang, and Yanfei Zhong. "Least Angle Regression-Based Constrained Sparse Unmixing of Hyperspectral Remote Sensing Imagery." Remote Sensing 10, no. 10 (2018): 1546. http://dx.doi.org/10.3390/rs10101546.

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Sparse unmixing has been successfully applied in hyperspectral remote sensing imagery analysis based on a standard spectral library known in advance. This approach involves reformulating the traditional linear spectral unmixing problem by finding the optimal subset of signatures in this spectral library using the sparse regression technique, and has greatly improved the estimation of fractional abundances in ubiquitous mixed pixels. Since the potentially large standard spectral library can be given a priori, the most challenging task is to compute the regression coefficients, i.e., the fractio

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23

Danilovich, T., S. Ramstedt, D. Gobrecht, L. Decin, E. De Beck, and H. Olofsson. "Sulphur-bearing molecules in AGB stars." Astronomy & Astrophysics 617 (September 2018): A132. http://dx.doi.org/10.1051/0004-6361/201833317.

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Context. Sulphur has long been known to form different molecules depending on the chemical composition of its environment. More recently, the sulphur-bearing molecules SO and H2S have been shown to behave differently in oxygen-rich asymptotic giant branch (AGB) circumstellar envelopes of different densities. Aims. By surveying a diverse sample of AGB stars for CS and SiS emission, we aim to determine in which environments these sulphur-bearing molecules most readily occur. We include sources with a range of mass-loss rates and carbon-rich, oxygen-rich, and mixed S-type chemistries. Where these

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24

Nomura, H., A. Higuchi, N. Sakai, et al. "ALMA observations of sulfur-bearing molecules in protoplanetary disks." Proceedings of the International Astronomical Union 14, S345 (2018): 360–61. http://dx.doi.org/10.1017/s1743921319002072.

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AbstractIt is thought that protoplanets formed in protoplanetary disks excite the orbital motion of the surrounding planetesimals, and the bow shocks caused by the highly excited planetesimals heat their icy component evaporating into gas. We have performed model calculations to study the evolution of molecular abundances of the evaporated icy component, which suggests sulfur-bearing molecules can be good tracers of icy planetesimal evaporation. Here we report the result of our ALMA observations of sulfur-bearing molecules towards protoplanetary disks. The lines were undetected but the obtaine

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Agúndez, M., N. Marcelino, J. Cernicharo, and M. Tafalla. "Detection of interstellar HCS and its metastable isomer HSC: new pieces in the puzzle of sulfur chemistry." Astronomy & Astrophysics 611 (March 2018): L1. http://dx.doi.org/10.1051/0004-6361/201832743.

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We present the first identification in interstellar space of the thioformyl radical (HCS) and its metastable isomer HSC. These species were detected toward the molecular cloud L483 through observations carried out with the IRAM 30 m telescope in the λ3 mm band. We derive beam-averaged column densities of 7 × 1012 cm−2 for HCS and 1.8 × 1011 cm−2 for HSC, which translate into fractional abundances relative to H2 of 2 × 10−10 and 6 × 10−12, respectively. Although the amount of sulfur locked by these radicals is low, their detection allows placing interesting constraints on the chemistry of sulfu

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Rubin, R. H., N. J. Bhatt, R. J. Dufour, et al. "Temperature Variations from HST Imagery and Spectroscopy of NGC 7009." Symposium - International Astronomical Union 209 (2003): 361–62. http://dx.doi.org/10.1017/s0074180900209017.

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We obtained new HST/STIS long-slit spectra and WFPC2 imagery of the planetary nebula NGC 7009 in order to obtain high spatial resolution of the intrinsic flux ratio [O III] 4364/5008, which is a well-known diagnostic for electron temperature (Te). Our primary purpose was to quantify Te variations across the nebula. We address whether the observational data support the possibility that the [fractional] mean-square Te variation (t2) (Peimbert 1967) in NGC 7009 may be as large as ~0.1. Such large values are required to reconcile the “abundance dichotomy” by Te variations alone. The abundance dich

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Rivière-Marichalar, P., A. Fuente, J. R. Goicoechea, et al. "Abundances of sulphur molecules in the Horsehead nebula." Astronomy & Astrophysics 628 (July 29, 2019): A16. http://dx.doi.org/10.1051/0004-6361/201935354.

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Context. Sulphur is one of the most abundant elements in the Universe (S/H ~ 1.3 × 10−5) and plays a crucial role in biological systems on Earth. The understanding of its chemistry is therefore of major importance. Aims. Our goal is to complete the inventory of S-bearing molecules and their abundances in the prototypical photodissociation region (PDR) the Horsehead nebula to gain insight into sulphur chemistry in UV irradiated regions. Based on the WHISPER (Wide-band High-resolution Iram-30 m Surveys at two positions with Emir Receivers) millimeter (mm) line survey, our goal is to provide an i

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Velilla-Prieto, L., J. Cernicharo, M. Agúndez та ін. "IRC + 10°216 mass loss properties through the study of λ3 mm emission". Astronomy & Astrophysics 629 (вересень 2019): A146. http://dx.doi.org/10.1051/0004-6361/201834717.

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Low-mass evolved stars are major contributors to interstellar medium enrichment as a consequence of the intense mass-loss process these stars experience at the end of their lives. The study of the gas in the envelopes surrounding asymptotic giant branch (AGB) stars through observations in the millimetre wavelength range provides information about the history and nature of these molecular factories. Here we present ALMA observations at subarsecond resolution, complemented with IRAM-30 m data, of several lines of SiO, SiS, and CS towards the best-studied AGB circumstellar envelope, IRC + 10°216.

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Koelemay, L. A., and L. M. Ziurys. "NO and c-C₃H₂ in the Outer Galaxy: High Molecular Abundances at R _GC > 13 kpc." Astrophysical Journal 986, no. 2 (2025): 122. https://doi.org/10.3847/1538-4357/add32d.

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Abstract Observations of the J Ka, Kc = 41,4 → 30,3, 40,4 → 31,3, and 22,0 → 11,1 rotational lines of c-C3H2 and the J = 3/2 → 1/2, Ω = 1/2 transition of NO (X2Πr) were conducted at 2 mm toward 20 Galactic edge clouds with R GC = 10.8–23.5 kpc using the Arizona Radio Observatory 12 m telescope. The c-C3H2 molecule was detected in all 20 objects in the sample, based typically on 2–3 transitions. NO, which exhibits a distinct pattern of lambda doubling and hyperfine splitting in the measured line, was identified in 16 clouds, with distances as far as R GC ∼ 23.5 kpc. While a 3 mm transition of c

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Raberg, Jonathan H., David J. Harning, Sarah E. Crump, et al. "Revised fractional abundances and warm-season temperatures substantially improve brGDGT calibrations in lake sediments." Biogeosciences 18, no. 12 (2021): 3579–603. http://dx.doi.org/10.5194/bg-18-3579-2021.

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Abstract. Distributions of branched glycerol dialkyl glycerol tetraethers (brGDGTs) are frequently employed for reconstructing terrestrial paleotemperatures from lake sediment archives. Although brGDGTs are globally ubiquitous, the microbial producers of these membrane lipids remain unknown, precluding a full understanding of the ways in which environmental parameters control their production and distribution. Here, we advance this understanding in three ways. First, we present 43 new high-latitude lake sites characterized by low mean annual air temperatures (MATs) and high seasonality, fillin

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Krudysz-Amblo, Jolanta, Mark E. Jennings, Dwight E. Matthews, Kenneth G. Mann, and Saulius Butenas. "Differences in the fractional abundances of carbohydrates of natural and recombinant human tissue factor." Biochimica et Biophysica Acta (BBA) - General Subjects 1810, no. 4 (2011): 398–405. http://dx.doi.org/10.1016/j.bbagen.2010.12.003.

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Lee, H. H., R. P. A. Bettens, and E. Herbst. "Fractional abundances of molecules in dense interstellar clouds: A compendium of recent model results." Astronomy and Astrophysics Supplement Series 119, no. 1 (1996): 111–14. http://dx.doi.org/10.1051/aas:1996232.

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Goodwin, Nicholas, Nicholas C. Coops, and Christine Stone. "Assessing plantation canopy condition from airborne imagery using spectral mixture analysis and fractional abundances." International Journal of Applied Earth Observation and Geoinformation 7, no. 1 (2005): 11–28. http://dx.doi.org/10.1016/j.jag.2004.10.003.

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Riedlova, Petra, Dagmar Kramna, Silvie Ostrizkova, Hana Tomaskova, and Vitezslav Jirik. "The Effectiveness of ddPCR for Detection of Point Mutations in Poor-Quality Saliva Samples." Healthcare 10, no. 5 (2022): 947. http://dx.doi.org/10.3390/healthcare10050947.

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Background: The noninvasive collection of saliva samples for DNA analyses is simple, and its potential for research and diagnostic purposes is great. However, DNA isolates from such samples are often of inferior quality to those from blood. Aim: The aim of this study was to investigate the robustness and sensitivity of the ddPCR instrument for genetic analyses from saliva samples of poor quality by comparing their results to those obtained using an established method from blood samples. Methods: Blood and saliva were collected from 47 university students, which was followed by manual isolation

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Syeda, Mahrukh M., Miranda Ortega, Christine Cordova, Alexandra Michelle Miller, and David Polsky. "Development and validation of a droplet digital PCR (ddPCR) assay to detect MGMT promoter methylation in FFPE tumors of glioblastoma (GBM) patients." Journal of Clinical Oncology 43, no. 16_suppl (2025): 2072. https://doi.org/10.1200/jco.2025.43.16_suppl.2072.

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2072 Background: Methylation of the MGMT gene promoter (MGMTp) is a critical biomarker to inform GBM prognosis and guide treatment decisions, including clinical trial eligibility. Rapid reporting of MGMTp methylation can help stratify patients early and facilitate clinical trial referral during the crucial post-operative period where treatment options are being considered by patients and physicians alike. Methods: We developed a probe-based ddPCR method to detect and quantify MGMTp methylation. Assay specificity was assessed using bisulfite-converted, unmethylated DNA. Assay linearity and Limi

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Tans, Pieter P., Andrew M. Crotwell, and Kirk W. Thoning. "Abundances of isotopologues and calibration of CO<sub>2</sub> greenhouse gas measurements." Atmospheric Measurement Techniques 10, no. 7 (2017): 2669–85. http://dx.doi.org/10.5194/amt-10-2669-2017.

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Abstract. We have developed a method to calculate the fractional distribution of CO2 across all of its component isotopologues based on measured δ13C and δ18O values. The fractional distribution can be used with known total CO2 to calculate the amount of substance fraction (mole fraction) of each component isotopologue in air individually. The technique is applicable to any molecule where isotopologue-specific values are desired. We used it with a new CO2 calibration system to account for isotopic differences among the primary CO2 standards that define the WMO X2007 CO2-in-air calibration scal

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Miettinen, O. "What did the seahorse swallow? APEX 170 GHz observations of the chemical conditions in the Seahorse infrared dark cloud." Astronomy & Astrophysics 639 (July 2020): A65. http://dx.doi.org/10.1051/0004-6361/202037817.

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Context. Infrared dark clouds (IRDCs) are useful target sources for the studies of molecular cloud substructure evolution and early stages of star formation. Determining the chemical composition of IRDCs helps to constrain the initial conditions and timescales (via chemical clocks) of star formation in these often filamentary, dense interstellar clouds. Aims. We aim to determine the fractional abundances of multiple different molecular species in the filamentary IRDC G304.74+01.32, nicknamed the Seahorse IRDC, and to search for relationships between the abundances and potential evolutionary tr

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Higgins, Michael D., and R. Doig. "Geochemical constraints on the differentiation processes that were active in the Sept Iles complex." Canadian Journal of Earth Sciences 23, no. 5 (1986): 670–81. http://dx.doi.org/10.1139/e86-067.

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Major- and trace-element abundances in the major units (gabbro, anorthosite, monzonite, syenite, and granite) of the unmetamorphosed Sept Iles complex have been evaluated to determine if these rocks can be related by simple magmatic processes or if it is necessary to invoke separately derived magmas. Major-element mass-balance and trace-element distribution calculations indicate that the diorite and quartz syenite were produced by fractional crystallization of plagioclase and augite, together with minor hypersthene and ilmenite, from a parental gabbroic magma. The Sr depletion of the granite,

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Fuente, A., D. G. Navarro, P. Caselli, et al. "Gas phase Elemental abundances in Molecular cloudS (GEMS)." Astronomy & Astrophysics 624 (April 2019): A105. http://dx.doi.org/10.1051/0004-6361/201834654.

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GEMS is an IRAM 30 m Large Program whose aim is determining the elemental depletions and the ionization fraction in a set of prototypical star-forming regions. This paper presents the first results from the prototypical dark cloud Taurus molecular cloud (TMC) 1. Extensive millimeter observations have been carried out with the IRAM 30 m telescope (3 and 2 mm) and the 40 m Yebes telescope (1.3 cm and 7 mm) to determine the fractional abundances of CO, HCO+, HCN, CS, SO, HCS+, and N2H+ in three cuts which intersect the dense filament at the well-known positions TMC 1-CP, TMC 1-NH3, and TMC 1-C, c

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Schmidt, D. R., and L. M. Ziurys. "The Remarkable Molecular Content of Planetary Nebulae." Proceedings of the International Astronomical Union 13, S332 (2017): 218–24. http://dx.doi.org/10.1017/s1743921317011589.

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AbstractIn order to further define the molecular content of planetary nebulae (PNe), we have conducted searches for HCN, HCO+, HNC, and CCH at millimeter wavelengths in a sample of seventeen PNe using the new 12 m and Sub-Millimeter Telescopes of the Arizona Radio Observatory (ARO). HCN and HCO+ were identified in 75% of the PNe, with corresponding fractional abundances of f(HCN/H2) ~ 0.1-9.1 × 10−7 and f(HCO+/H2) ~ 0.04-7.4 × 10−7. HNC was subsequently identified in twelve PNe with f(HNC/H2) ~ 0.02-2.2 × 10−7. The [HCN]/[HNC] ratio was found to be ~1-8 in nebulae observed. CCH was also detect

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An, Rui, Ethan O. Nadler, Andrew Benson, and Vera Gluscevic. "COZMIC. II. Cosmological Zoom-in Simulations with Fractional non-CDM Initial Conditions." Astrophysical Journal 986, no. 2 (2025): 128. https://doi.org/10.3847/1538-4357/adce83.

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Abstract We present 24 cosmological dark matter (DM)-only zoom-in simulations of a Milky Way analog with initial conditions appropriate for scenarios where non-cold dark matter (NCDM) is a fraction of the total DM abundance (f-NCDM models) as the second installment of the COZMIC suite. We initialize our simulations using transfer functions, T f − NCDM ( k ) ≡ P f − NCDM ( k ) / P CDM ( k ) (where P(k) is the linear matter power spectrum), with an initial suppression similar to thermal-relic warm dark matter (WDM) followed by a constant-amplitude plateau. We simulate suppression wavenumbers [22

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Bernal, J. J., C. D. Sephus, and L. M. Ziurys. "Methanol at the Edge of the Galaxy: New Observations to Constrain the Galactic Habitable Zone." Astrophysical Journal 922, no. 2 (2021): 106. http://dx.doi.org/10.3847/1538-4357/ac27a6.

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Abstract The Galactic Habitable Zone (GHZ) is a region believed hospitable for life. To further constrain the GHZ, observations have been conducted of the J = 2 → 1 transitions of methanol (CH3OH) at 97 GHz, toward 20 molecular clouds located in the outer Galaxy (R GC = 12.9–23.5 kpc), using the 12 m telescope of the Arizona Radio Observatory. Methanol was detected in 19 out of 20 observed clouds, including sources as far as R GC = 23.5 kpc. Identification was secured by the measurement of multiple asymmetry and torsional components in the J = 2 → 1 transition, which were resolved in the narro

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Vale Asari, N., G. S. Couto, R. Cid Fernandes, et al. "Diffuse ionized gas and its effects on nebular metallicity estimates of star-forming galaxies." Monthly Notices of the Royal Astronomical Society 489, no. 4 (2019): 4721–33. http://dx.doi.org/10.1093/mnras/stz2470.

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ABSTRACT We investigate the impact of the diffuse ionized gas (DIG) on abundance determinations in star-forming (SF) galaxies. The DIG is characterized using the H α equivalent width (WH α). From a set of 1 409 SF galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey, we calculate the fractional contribution of the DIG to several emission lines using high-S/N data from SF spaxels (instead of using noisy emission-lines in DIG-dominated spaxels). Our method is applicable to spectra with observed WH α ≳ 10 Å (which are not dominated by DIG emission). Since the DIG contribution depends o

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Bordiu, C., J. R. Rizzo, F. Bufano та ін. "First Detection of Silicon-bearing Molecules in η Car". Astrophysical Journal Letters 939, № 2 (2022): L30. http://dx.doi.org/10.3847/2041-8213/ac9b10.

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Abstract We present ALMA band 6 observations of the luminous blue variable η Car obtained within the ALMAGAL program. We report SiO J = 5 → 4, SiS J = 12 → 11, and SiN N = 5 → 4 emission in the equatorial region of the Homunculus nebula, constituting the first detection of silicon- and sulfur-bearing molecules in the outskirts of a highly evolved, early-type massive star. The SiO, SiS, and SiN trace a clumpy equatorial ring that surrounds the central binary at a projected distance of ∼2″, delineating the inner rims of the butterfly-shaped dusty region. The formation of silicon-bearing compound

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Kharroubi, A. T., T. M. Masterson, T. A. Aldaghlas, K. A. Kennedy, and J. K. Kelleher. "Isotopomer spectral analysis of triglyceride fatty acid synthesis in 3T3-L1 cells." American Journal of Physiology-Endocrinology and Metabolism 263, no. 4 (1992): E667—E675. http://dx.doi.org/10.1152/ajpendo.1992.263.4.e667.

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A new analysis of stable isotope data for biosynthesis reaction, isotopomer spectral analysis (ISA), is demonstrated. ISA is theoretically applicable for polymerization biosynthesis where data are collected using selected ion-monitoring gas chromatography-mass spectrometry. ISA utilizes the discrete spectrum of isotopomer abundances and the multinomial distribution to estimate two key parameters related to the biosynthesis. These parameters are 1) the dilution of the precursor immediately before biosynthesis and 2) the dilution of the newly synthesized product in the sampled compartment. Diffe

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Taniguchi, Kotomi, Patricio Sanhueza, Fernando A. Olguin, et al. "Digging into the Interior of Hot Cores with the ALMA (DIHCA). III. The Chemical Link between NH₂CHO, HNCO, and H₂CO." Astrophysical Journal 950, no. 1 (2023): 57. http://dx.doi.org/10.3847/1538-4357/acca1d.

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Abstract We have analyzed the NH2CHO, HNCO, H2CO, and CH3CN (13CH3CN) molecular lines at an angular resolution of ∼0.″3 obtained by the Atacama Large Millimeter/submillimeter Array Band 6 toward 30 high-mass star-forming regions. The NH2CHO emission has been detected in 23 regions, while the other species have been detected toward 29 regions. A total of 44 hot molecular cores (HMCs) have been identified using the moment 0 maps of the CH3CN line. The fractional abundances of the four species have been derived at each HMC. In order to investigate pure chemical relationships, we have conducted a

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Dabiri, Rahim, Mohamad Emami, Habib Mollaei, et al. "Quaternary post-collision alkaline volcanism NW of Ahar (NW Iran): geochemical constraints of fractional crystallization process." Geologica Carpathica 62, no. 6 (2011): 547–62. http://dx.doi.org/10.2478/v10096-011-0039-2.

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Quaternary post-collision alkaline volcanism NW of Ahar (NW Iran): geochemical constraints of fractional crystallization process Major and trace elements and Sr-Nd isotopic data are presented for the Quaternary alkaline volcanism NW of Ahar (NW Iran). The exposed rocks mainly consist of alkali basalts, trachybasalts, basaltic trachyandesites and trachyandesites. Alkali basalts and trachybasalts display microlithic porphyritic texture with phenocrysts of olivine, clinopyroxene, and plagioclase in microlithic groundmass. In the more evolved rocks (basaltic trachyandesites and trachyandesites), a

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Minghelli, Audrey, Sayoob Vadakke-Chanat, Malik Chami, et al. "Estimation of Bathymetry and Benthic Habitat Composition from Hyperspectral Remote Sensing Data (BIODIVERSITY) Using a Semi-Analytical Approach." Remote Sensing 13, no. 10 (2021): 1999. http://dx.doi.org/10.3390/rs13101999.

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The relevant benefits of hyperspectral sensors for water column determination and seabed features mapping compared to multispectral data, especially in coastal areas, have been demonstrated in recent studies. In this study, we used hyperspectral satellite data in the accurate mapping of the bathymetry and the composition of water habitats for inland water. Particularly, the identification of the bottom diversity for a shallow lagoon (less than 2 m in depth) was examined. Hyperspectral satellite data were simulated based on aerial hyperspectral imagery acquired above a lagoon, namely the Vaccar

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Dors, O. L., M. Contini, R. A. Riffel, et al. "Chemical abundances of Seyfert 2 AGNs – IV. Composite models calculated by photoionization + shocks." Monthly Notices of the Royal Astronomical Society 501, no. 1 (2020): 1370–83. http://dx.doi.org/10.1093/mnras/staa3707.

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ABSTRACT We build detailed composite models of photoionization and shock ionization based on the suma code to reproduce emission lines emitted from the Narrow Line Regions (NLR) of Seyfert 2 nuclei. The aim of this work is to investigate diagram active galactic nucleus (AGN) positions according to shock parameters, shock effects on the gas temperature and ionization structures and derive a semi-empirical abundance calibration based on emission-line ratios little sensitive to the shock presence. The models were used to reproduce optical (3000 &lt; λ(Å) &lt; 7000) emission line intensiti

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Tuck, Adrian F., Christopher R. Webster, Randy D. May, et al. "Time and temperature dependences of fractional HCl abundances from airborne data in the Southern Hemisphere during 1994." Faraday Discussions 100 (1995): 389. http://dx.doi.org/10.1039/fd9950000389.

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