157 research outputs found

    Extreme quasars at high redshift

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    Context:Quasars radiating at extreme Eddington ratios (xA) are likely a prime mover of galactic evolution and have been hailed as potential distance indicators. Their properties are still scarcely known. Aims:We test the effectiveness of the selection criteria defined on the 4D Eigenvector 1 (4DE1) for identifying xA sources. We provide a quantitative description of their UV spectra in the redshift range 2<z<2.9. Methods:19 extreme quasar candidates were identified using 4DE1 selection criteria applied to SDSS spectra: AlIII1860/SiIII]1892>0.5 and CIII]1909/SiIII]1892<1. The emission line spectra was studied using multicomponent fits of deep spectroscopic observations obtained with the OSIRIS-GTC. Results:Spectra confirm that almost all of these quasars are xA sources with very similar properties. We provide spectrophotometric and line profile measurements for the SiIV1397+OIV]1402, CIV1549+HeII1640, and the 1900A blend composed by AlIII1860, SiIII]1892, FeIII and a weak CIII]1909. The spectra can be characterized as very low ionization (logU~-3), a condition that explains the significant FeIII emission. CIV1549 shows low equivalent width (<30 A for the most sources), and high or extreme blueshift amplitudes (-5000<c(1/2)<-1000 kms-1). Weak-lined quasars appear as extreme xA quasars and not as an independent class. The CIV1549 high amplitude blueshifts coexists in all cases save one with symmetric and narrower AlIII and SiIII] profiles. Estimates of the Eddington ratio using the AlIII FWHM as a virial broadening estimator are consistent with the ones of a previous xA sample. Conclusions:It is now feasible to assemble large samples of xA quasars from the latest data releases of the SDSS. We provide evidence that AlIII1860 could be associated with a low-ionization virialized sub-system, supporting previous suggestions that AlIII is a reliable virial broadening estimator.Comment: 36 pages, 31 figures, 12 tables. Manuscript accepted for publication, A&A. Corrected titl

    Evaluation of rare earth doped silica sub-micrometric spheres as optically controlled temperature sensors

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    We report on the evaluation of rare earth (Er3þ, Eu3þ, and Tb3þ ions) SiO2 sub-micrometric spheres as potential optically controllable temperature sensors. Details about fabrication, optical manipulation and spectroscopic characterization of the sub-micrometric spheres are presented. The fluorescence properties of the micros-spheres in the biological range (25–60 C) have been systematically investigated. From this systematic study, the thermal resolution potentially achieved in each case has been determined and compared to previous works

    Set-optimization meets variational inequalities

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    We study necessary and sufficient conditions to attain solutions of set-optimization problems in therms of variational inequalities of Stampacchia and Minty type. The notion of a solution we deal with has been introduced Heyde and Loehne, for convex set-valued objective functions. To define the set-valued variational inequality, we introduce a set-valued directional derivative and we relate it to the Dini derivatives of a family of linearly scalarized problems. The optimality conditions are given by Stampacchia and Minty type Variational inequalities, defined both by the set valued directional derivative and by the Dini derivatives of the scalarizations. The main results allow to obtain known variational characterizations for vector valued optimization problems

    Network meta‐analysis of post‐exposure prophylaxis randomized clinical trials

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    Objectives: We performed a network meta‐analysis of PEP randomized clinical trials to evaluate the best regimen. / Methods: After MEDLINE/Pubmed search, studies were included if: (1) were randomized, (2) comparing at least 2 PEP three‐drug regimens and, (3) reported completion rates or discontinuation at 28 days. Five studies with 1105 PEP initiations were included and compared ritonavir‐boosted lopinavir (LPV/r) vs. atazanavir (ATV) (one study), cobicistat‐boosted elvitegravir (EVG/c) (one study), raltegravir (RAL) (one study) or maraviroc (MVC) (two studies). We estimated the probability of each treatment of being the best based on the evaluation of five outcomes: PEP non‐completion at day 28, PEP discontinuation due to adverse events, PEP switching due to any cause, lost to follow‐up and adverse events. / Results: Participants were mostly men who have sex with men (n = 832, 75%) with non‐occupational exposure to HIV (89.86%). Four‐hundred fifty‐four (41%) participants failed to complete their PEP course for any reason. The Odds Ratio (OR) for PEP non‐completion at day 28 in each antiretroviral compared to LPV/r was: ATV 0.95 (95% CI 0.58–1.56; EVG/c: OR 0.65 95% CI 0.30–1.37; RAL: OR 0.68 95% CI 0.41–1.13; and MVC: OR 0.69 95% CI 0.47–1.01. In addition, the rankogram showed that EVG/c had the highest probability of being the best treatment for the lowest rates in PEP non‐completion at day 28, switching, lost to follow‐up or adverse events and MVC for PEP discontinuations due to adverse events. / Conclusions: Our study shows the advantages of integrase inhibitors when used as PEP, particularly EVG as a Single‐Tablet Regimen

    The Antares Collaboration : Contributions to the 34th International Cosmic Ray Conference (ICRC 2015, The Hague)

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    The ANTARES detector, completed in 2008, is the largest neutrino telescope in the Northern hemisphere. Located at a depth of 2.5 km in the Mediterranean Sea, 40 km off the Toulon shore, its main goal is the search for astrophysical high energy neutrinos. In this paper we collect the 21 contributions of the ANTARES collaboration to the 34th International Cosmic Ray Conference (ICRC 2015). The scientific output is very rich and the contributions included in these proceedings cover the main physics results, ranging from steady point sources, diffuse searches, multi-messenger analyses to exotic physics

    A Hybrid of Metabolic Flux Analysis and Bayesian Factor Modeling for Multiomic Temporal Pathway Activation.

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    The growing availability of multiomic data provides a highly comprehensive view of cellular processes at the levels of mRNA, proteins, metabolites, and reaction fluxes. However, due to probabilistic interactions between components depending on the environment and on the time course, casual, sometimes rare interactions may cause important effects in the cellular physiology. To date, interactions at the pathway level cannot be measured directly, and methodologies to predict pathway cross-correlations from reaction fluxes are still missing. Here, we develop a multiomic approach of flux-balance analysis combined with Bayesian factor modeling with the aim of detecting pathway cross-correlations and predicting metabolic pathway activation profiles. Starting from gene expression profiles measured in various environmental conditions, we associate a flux rate profile with each condition. We then infer pathway cross-correlations and identify the degrees of pathway activation with respect to the conditions and time course using Bayesian factor modeling. We test our framework on the most recent metabolic reconstruction of Escherichia coli in both static and dynamic environments, thus predicting the functionality of particular groups of reactions and how it varies over time. In a dynamic environment, our method can be readily used to characterize the temporal progression of pathway activation in response to given stimuli

    Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory

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    The Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E>Eth=5.5×1019E>E_{th}=5.5\times 10^{19} eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at E>EthE>E_{th} are heavy nuclei with charge ZZ, the proton component of the sources should lead to excesses in the same regions at energies E/ZE/Z. We here report the lack of anisotropies in these directions at energies above Eth/ZE_{th}/Z (for illustrative values of Z=6, 13, 26Z=6,\ 13,\ 26). If the anisotropies above EthE_{th} are due to nuclei with charge ZZ, and under reasonable assumptions about the acceleration process, these observations imply stringent constraints on the allowed proton fraction at the lower energies

    High-Bandpass Filters in Electrocardiography: Source of Error in the Interpretation of the ST Segment

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    Introduction. Artifactual variations in the ST segment may lead to confusion with acute coronary syndromes. Objective. To evaluate how the technical characteristics of the recording mode may distort the ST segment. Material and Method. We made a series of electrocardiograms using different filter configurations in 45 asymptomatic patients. A spectral analysis of the electrocardiograms was made by discrete Fourier transforms, and an accurate recomposition of the ECG signal was obtained from the addition of successive harmonics. Digital high-pass filters of 0.05 and 0.5 Hz were used, and the resulting shapes were compared with the originals. Results. In 42 patients (93%) clinically significant alterations in ST segment level were detected. These changes were only seen in “real time mode” with high-pass filter of 0.5 Hz. Conclusions. Interpretation of the ST segment in “real time mode” should only be carried out using high-pass filters of 0.05 Hz.Buendıa Fuentes, F.; Arnau Vives, M.; Arnau Vives, A.; Jiménez Jiménez, Y.; Rueda-Soriano, J.; Zorio-Grima, E..; Osa-Saez, A.... (2012). High-Bandpass Filters in Electrocardiography: Source of Error in the Interpretation of the ST Segment. ISRN Cardiology. 2012:706217-706227. doi:10.5402/2012/706217S706217706227201

    Effects of Genotype and Growth Temperature on the Contents of Tannin, Phytate and in vitro Iron Availability of Sorghum Grains

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    Background: It has been predicted that the global temperature will rise in the future, which means crops including sorghum will likely be grown under higher temperatures, and consequently may affect the nutritional properties. Methods: The effects of two growth temperatures (OT, day/night 32/21°C; HT 38/21°C) on tannin, phytate, mineral, and in vitro iron availability of raw and cooked grains (as porridge) of six sorghum genotypes were investigated. Results: Tannin content significantly decreased across all sorghum genotypes under high growth temperature (P ≤0.05), while the phytate and mineral contents maintained the same level, increased or decreased significantly, depending on the genotype. The in vitro iron availability in most sorghum genotypes was also significantly reduced under high temperature, except for Ai4, which showed a pronounced increase (P ≤0.05). The cooking process significantly reduced tannin content in all sorghum genotypes (P ≤0.05), while the phytate content and in vitro iron availability were not significantly affected. Conclusions: This research provides some new information on sorghum grain nutritional properties when grown under predicted future higher temperatures, which could be important for humans where sorghum grains are consumed as staple food

    Advanced functionality for radio analysis in the Offline software framework of the Pierre Auger Observatory

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    The advent of the Auger Engineering Radio Array (AERA) necessitates the development of a powerful framework for the analysis of radio measurements of cosmic ray air showers. As AERA performs "radio-hybrid" measurements of air shower radio emission in coincidence with the surface particle detectors and fluorescence telescopes of the Pierre Auger Observatory, the radio analysis functionality had to be incorporated in the existing hybrid analysis solutions for fluoresence and surface detector data. This goal has been achieved in a natural way by extending the existing Auger Offline software framework with radio functionality. In this article, we lay out the design, highlights and features of the radio extension implemented in the Auger Offline framework. Its functionality has achieved a high degree of sophistication and offers advanced features such as vectorial reconstruction of the electric field, advanced signal processing algorithms, a transparent and efficient handling of FFTs, a very detailed simulation of detector effects, and the read-in of multiple data formats including data from various radio simulation codes. The source code of this radio functionality can be made available to interested parties on request.Comment: accepted for publication in NIM A, 13 pages, minor corrections to author list and references in v
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