We present the identification of 634 variable stars in the Milky Way dwarf spheroidal (dSph) satellite Sculptor based on archival ground-based optical observations spanning ∼24 yr and covering ...∼2.5 deg2. We employed the same methodologies as the ‘Homogeneous Photometry’ series published by Stetson. In particular, we have identified and characterized one of the largest (536) RR Lyrae samples so far in a Milky Way dSph satellite. We have also detected four Anomalous Cepheids, 23 SX Phoenicis stars, five eclipsing binaries, three field variable stars, three peculiar variable stars located above the horizontal branch – near to the locus of BL Herculis – that we are unable to classify properly. Additionally, we identify 37 long period variables plus 23 probable variable stars, for which the current data do not allow us to determine the period. We report positions and finding charts for all the variable stars, and basic properties (period, amplitude, mean magnitude) and light curves for 574 of them. We discuss the properties of the RR Lyrae stars in the Bailey diagram, which supports the coexistence of subpopulations with different chemical compositions. We estimate the mean mass of Anomalous Cepheids (∼1.5 M⊙) and SX Phoenicis stars (∼1 M⊙). We discuss in detail the nature of the former. The connections between the properties of the different families of variable stars are discussed in the context of the star formation history of the Sculptor dSph galaxy.
Using the data taken at the Pierre Auger Observatory between December 2004 and December 2012, we have examined the implications of the distributions of depths of atmospheric shower maximum (X ...sub(max)), using a hybrid technique, for composition and hadronic interaction models. We do this by fitting the distributions with predictions from a variety of hadronic interaction models for variations in the composition of the primary cosmic rays and examining the quality of the fit. Regardless of what interaction model is assumed, we find that our data are not well described by a mix of protons and iron nuclei over most of the energy range. Acceptable fits can be obtained when intermediate masses are included, and when this is done consistent results for the proton and iron-nuclei contributions can be found using the available models. We observe a strong energy dependence of the resulting proton fractions, and find no support from any of the models for a significant contribution from iron nuclei. However, we also observe a significant disagreement between the models with respect to the relative contributions of the intermediate components.
The Pierre Auger collaboration reports new results bearing on the composition of cosmic rays. The muon number of air showers, created by cosmic rays and measured by the collaboration, is intriguingly ...at odds with all theoretical models, posing a challenge to our current understanding of the mass composition of cosmic rays. We present the first hybrid measurement of the average muon number in air showers at ultrahigh energies, initiated by cosmic rays with zenith angles between 62degrees and 80degrees. The measurement is based on 174 hybrid events recorded simultaneously with the surface detector array and the fluorescence detector of the Pierre Auger Observatory. The muon number for each shower is derived by scaling a simulated reference profile of the lateral muon density distribution at the ground until it fits the data. A 10 super(19) eV shower with a zenith angle of 67degrees, which arrives at the surface detector array at an altitude of 1450 m above sea level, contains on average (2.68 + or - 0.04 + or - 0.48(sys)) x 10 super(7) muons with energies larger than 0.3 GeV. The logarithmic gain d ln N sub( mu )/d ln E of muons with increasing energy between 4 X 10 super(18) eV and 5 x 10 super(19) eV is measured to be (1.029 + or - 0.024 + or - 0.030(sys)).
The Pierre Auger Collaboration reports on its search for ultra high energy (UHE) neutrinos in the EeV range, three orders of magnitude above the highest energy neutrino events reported by IceCube. ...Analyzing over 9 years of data, the collaboration found no events, setting the strictest limits to date on the diffuse flux of UHE neutrinos. Neutrinos in the cosmic ray flux with energies near 1 EeV and above are detectable with the Surface Detector array (SD) of the Pierre Auger Observatory. We report here on searches through Auger data from 1 January 2004 until 20 June 2013. No neutrino candidates were found, yielding a limit to the diffuse flux of ultrahigh energy neutrinos that challenges the Waxman-Bahcall bound predictions. Neutrino identification is attempted using the broad time structure of the signals expected in the SD stations, and is efficiently done for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for "Earth-skimming" neutrino interactions in the case of tau neutrinos. In this paper the searches for downward-going neutrinos in the zenith angle bins 60degrees-75degrees and 75degrees-90degrees as well as for upward-going neutrinos, are combined to give a single limit. The 90% C.L. single-flavor limit to the diffuse flux of ultrahigh energy neutrinos with an E super(-2) spectrum in the energy range 1.0 x 10 super(17) eV -2.5 x 10 super(19) eV is (ProQuest: Formulae and/or non-USASCII text omitted) GeV cm super(-2) s super(-1) sr super(-1).
Gas and liquid chromatography coupled to triple quadrupole tandem mass spectrometry are currently the most powerful tools employed for the routine analysis of pesticide residues in food control ...laboratories. However, whatever the multiresidue extraction method, there will be a residual matrix effect making it difficult to identify/quantify some specific compounds in certain cases. Two main effects stand out: (i) co-elution with isobaric matrix interferents, which can be a major drawback for unequivocal identification, and therefore false negative detections, and (ii) signal suppression/enhancement, commonly called the “matrix effect”, which may cause serious problems including inaccurate quantitation, low analyte detectability and increased method uncertainty. The aim of this analytical study is to provide a framework for evaluating the maximum expected errors associated with the matrix effects. The worst-case study contrived to give an estimation of the extreme errors caused by matrix effects when extraction/determination protocols are applied in routine multiresidue analysis. Twenty-five different blank matrices extracted with the four most common extraction methods used in routine analysis (citrate QuEChERS with/without PSA clean-up, ethyl acetate and the Dutch mini-Luke “NL” methods) were evaluated by both GC-QqQ-MS/MS and LC-QqQ-MS/MS. The results showed that the presence of matrix compounds with isobaric transitions to target pesticides was higher in GC than under LC in the experimental conditions tested.
In a second study, the number of “potential” false negatives was evaluated. For that, ten matrices with higher percentages of natural interfering components were checked. Additionally, the results showed that for more than 90% of the cases, pesticide quantification was not affected by matrix-matched standard calibration when an interferent was kept constant along the calibration curve. The error in quantification depended on the concentration level. In a third study, the “matrix effect” was evaluated for each commodity/extraction method. Results showed 44% of cases with suppression/enhancement for LC and 93% of cases with enhancement for GC.
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•Estimation of the extreme error due to matrix effects.•Twenty five different matrices were tested by both GC-QqQ-MS/MS and LC-QqQ-MS/MS.•Evaluation of the four most commonly extraction methods used in routine.•“Potential” false negatives were higher in GC than in LC.•Higher percentages of interferences were found for NL-method.
We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we ...obtain a radiation energy of 15.8±0.7(stat)±6.7(syst) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principles calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.
Background Environmental DNA (eDNA) is the DNA that can be extracted from an environmental sample, enabling the monitoring of whole biological communities across a large number of samples, at a ...potentially lower cost, which can significantly benefit river conservation. A systematic mapping protocol was designed to investigate the use of eDNA in rivers, specifically in terms of research topics, geographic and taxonomic biases, as well as information gaps. Furthermore, the potential research opportunities of eDNA in rivers and possible paths to find this kind of information on available platforms are identified. Methods A published systematic map protocol was applied, consisting of a search for published articles and gray literature in two bibliographic databases and one search engine. All search results were submitted to a 2-stage screening for relevance and pertinence in accordance with pre-defined eligibility criteria. Data extraction and codification regarding country of study, year, taxonomic group, sequencing platform, and type of technique employed resulted in a publicly available database. Results From 7372 studies initially obtained by the search, 545 met the inclusion criteria spanning a period from 2003 to 2022. The five countries with most studies are: USA (134), Japan (61), China (54), Brazil (29) and the UK (25). The most used fragments to analyze DNA are 16S and COI, whilst 26S and 23S are the least used. Only 84 (15%) of the studies reported hypervariable regions, among which the most used are V4 and V5. Regarding taxonomic groups, fishes are most often studied (176), followed by bacteria (138) and virus (52), while fungi is the least studied group (3). Concerning data availability, 229 (42%) studies provided access to sequencing data. Conclusions This study presents a comprehensive analysis of the available evidence regarding the implementation of the eDNA methods in rivers. The findings indicate that since the year 2003, this approach has been applied to aquatic lotic systems, and their recent increase can be attributed to the development of Next-Generation-Sequencing technologies and their reduced costs. However, there is a bias towards high-income countries, particularly USA and Europe. Widespread use and applications of this approach at a global level would allow for the generation of a large amount of information that can be compared between countries to understand if responses of aquatic systems follow similar patterns worldwide. Keywords: Lotic, Water, Metagenomics, Global trends, ROSES, NGS
•Multiresidue method for edible vegetable oils using GC–MS/MS.•Evaluation of different sorbents for the clean-up step using QuEChERS methodology.•Comparison of the novel EMR-Lipid sorbent with Z-Sep ...and PSA.•Procedural Standard Calibration to correct recovery losses.•Several pesticides are detected in most of the olive oil samples.
The aim of this research was to adapt the QuEChERS method for routine pesticide multiresidue analysis in edible vegetable oil samples using gas chromatography coupled to tandem mass spectrometry (GC–MS/MS). Several clean-up approaches were tested: (a) D-SPE with Enhanced Matrix Removal-Lipid (EMR-Lipid™); (b) D-SPE with PSA; (c) D-SPE with Z-Sep; (d) SPE with Z-Sep. Clean-up methods were evaluated in terms of fat removal from the extracts, recoveries and extraction precision for 213 pesticides in different matrices (soybean, sunflower and extra-virgin olive oil). The QuEChERS protocol with EMR-Lipid d-SPE provided the best reduction of co-extracted matrix compounds with the highest number of pesticides exhibiting mean recoveries in the 70–120% range, and the lowest relative standard deviations values (4% on average). A simple and rapid (only 5min) freeze-out step with dry ice (CO2 at −76°C) prior to d-SPE clean-up ensured much better removal of co-extracted matrix compounds in compliance of the necessity in routine analysis. Procedural Standard Calibration was established in order to compensate for recovery losses of certain pesticides and possible matrix effects. Limits of quantification were 10μgkg−1 for the majority of the pesticides. The modified methodology was applied for the analysis of different 17 oil samples. Fourteen pesticides were detected with values lower than MRLs and their concentration ranged between 10.2 and 156.0μgkg−1.
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•Recording of the three AB release steps with Raman spectroscopy.•AB behavior in the first release step with different heating rates, by means of PCA.•Molecular dynamics proposal of ...AB before the first release step.
Ammonia borane, as a source of hydrogen, has attracted much attention due to its high hydrogen content, low molecular weight, and high stability in solution. However, the process and enhancement of hydrogen release must be done practically under ambient conditions. For this work, Raman spectroscopy, principal component analysis (PCA), and molecular simulation were applied to study the hydrogen release process of ammonia borane. Three stages of release were observed from room temperature to 1300 °C. The shift, the appearance, and the disappearance of the Raman bands were evident in the whole process. In-situ monitoring of Raman and PCA, with four different heating rates between 70 and 130 °C, was done; ammonia borane showed visible variations in its first release step, in which a fast rate helped reduce distortion in the release process. Finally, molecular simulation of ammonia borane using the Density Functional Theory (DFT) in calculations showed that dihedral rotation and stretching of the hydrogen bonds can occur before the first release step.
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