93 research outputs found

    A framework to measure the properties of intergalactic metal systems with two-point flux statistics

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    The abundance, temperature, and clustering of metals in the intergalactic medium are important parameters for understanding their cosmic evolution and quantifying their impact on cosmological analysis with the Ly α\alpha forest. The properties of these systems are typically measured from individual quasar spectra redward of the quasar's Ly α\alpha emission line, yet that approach may provide biased results due to selection effects. We present an alternative approach to measure these properties in an unbiased manner with the two-point statistics commonly employed to quantify large-scale structure. Our model treats the observed flux of a large sample of quasar spectra as a continuous field and describes the one-dimensional, two-point statistics of this field with three parameters per ion: the abundance (column density distribution), temperature (Doppler parameter) and clustering (cloud-cloud correlation function). We demonstrate this approach on multiple ions (e.g., C IV, Si IV, Mg II) with early data from the Dark Energy Spectroscopic Instrument (DESI) and high-resolution spectra from the literature. Our initial results show some evidence that the C IV abundance is higher than previous measurements and evidence for abundance evolution over time. The first full year of DESI observations will have over an order of magnitude more quasar spectra than this study. In a future paper we will use those data to measure the growth of clustering and its impact on the Ly α\alpha forest, as well as test other DESI analysis infrastructure such as the pipeline noise estimates and the resolution matrix.Comment: 15 pages, 14 figure

    Optimal 1D Lyα\alpha Forest Power Spectrum Estimation -- III. DESI early data

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    The one-dimensional power spectrum P1DP_{\mathrm{1D}} of the Lyα\alpha forest provides important information about cosmological and astrophysical parameters, including constraints on warm dark matter models, the sum of the masses of the three neutrino species, and the thermal state of the intergalactic medium. We present the first measurement of P1DP_{\mathrm{1D}} with the quadratic maximum likelihood estimator (QMLE) from the Dark Energy Spectroscopic Instrument (DESI) survey early data sample. This early sample of 54 60054~600 quasars is already comparable in size to the largest previous studies, and we conduct a thorough investigation of numerous instrumental and analysis systematic errors to evaluate their impact on DESI data with QMLE. We demonstrate the excellent performance of the spectroscopic pipeline noise estimation and the impressive accuracy of the spectrograph resolution matrix with two-dimensional image simulations of raw DESI images that we processed with the DESI spectroscopic pipeline. We also study metal line contamination and noise calibration systematics with quasar spectra on the red side of the Lyα\alpha emission line. In a companion paper, we present a similar analysis based on the Fast Fourier Transform estimate of the power spectrum. We conclude with a comparison of these two approaches and implications for the upcoming DESI Year 1 analysis.Comment: 23 pages, 20 figures. To be published in MNRA

    Determination of the optimal matching position for setup images and minimal setup margins in adjuvant radiotherapy of breast and lymph nodes treated in voluntary deep inhalation breath-hold

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    Background Adjuvant radiotherapy (RT) of left-sided breast cancer is increasingly performed in voluntary deep inspiration breath-hold (vDIBH). The aim of this study was to estimate the reproducibility of breath-hold level (BHL) and to find optimal bony landmarks for matching of orthogonal setup images to minimise setup margins. Methods 1067 sets of images with an orthogonal setup and tangential field from 67 patients were retrospectively analysed. Residual position errors were determined in the tangential treatment field images for different matches of the setup images. Variation of patient posture and BHL were analysed for position errors of the vertebrae, clavicula, ribs and sternum in the setup and tangential field images. The BHL was controlled with a Varian RPM® system. Setup margins were calculated using the van Herk’s formula. Patients who underwent lymph node irradiation were also investigated. Results For the breast alone, the midway compromise of the ribs and sternum was the best general choice for matching of the setup images. The required margins were 6.5 mm and 5.3 mm in superior-inferior (SI) and lateral/anterior-posterior (LAT/AP) directions, respectively. With the individually optimised image matching position also including the vertebrae, slightly smaller margins of 6.0 mm and 4.8 mm were achieved, respectively. With the individually optimised match, margins of 7.5 mm and 10.8 mm should be used in LAT and SI directions, respectively, for the lymph node regions. These margins were considered too large. The reproducibility of the BHL was within 5 mm in the AP direction for 75% of patients. Conclusions The smallest setup margins were obtained when the matching position of the setup images was individually optimised for each patient. Optimal match for the breast alone is not optimal for the lymph node region, and, therefore, a threshold of 5 mm was introduced for residual position errors of the sternum, upper vertebrae, clavicula and chest wall to retain minimal setup margins of 5 mm. Because random interfraction variation in patient posture was large, we recommend daily online image guidance. The BHL should be verified with image guidance.BioMed Central open acces

    The Influence of Conflict on the Demand for Education in the Basque Region

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    It has previously been shown that civil conflict influences many economic factors, including education, which play an important role in development and economic growth. Previous authors working on the influence of conflict on education have, however, always focused strongly on the supply-side effects, whereas this paper examines the influence of conflict on the demand for education. It is theoretically shown that, under relatively general conditions, individuals living in a conflict area have an incentive to increase their level of education and that this effect depends on the individual's skill level. This hypothesis is then tested using the conflict in the Basque Region as a case study, which is an example of a conflict in which one would not expect strong supply-side effects. Using the other Spanish regions, an artificial region is created in which the population has a similar educational distribution as in the Basque Region. When comparing the true and artificial regions, it can clearly be seen that for individuals with a medium level of education, there is a strong incentive to increase their education level, which is in concordance with the theoretical model

    Bleomycin-induced in vitro 3D spheroid model to emulate pulmonary fibrosis

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    [No Abstract Available]Ege University Scientific Research Fund (Grant number: FGA-2020-21686) and Presidency of the Republic of Turkey, Presidency of Strategy and Budget (Grant number: 2019K12-149080) are appreciated for their supports.Ege University Scientific Research Fund [FGA-2020-21686]; Presidency of the Republic of Turkey, Presidency of Strategy and Budget [2019K12-149080
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