177 research outputs found

    The Extremely Luminous Quasar Survey (ELQS) in the SDSS footprint I.: Infrared Based Candidate Selection

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    Studies of the most luminous quasars at high redshift directly probe the evolution of the most massive black holes in the early Universe and their connection to massive galaxy formation. However, extremely luminous quasars at high redshift are very rare objects. Only wide area surveys have a chance to constrain their population. The Sloan Digital Sky Survey (SDSS) has so far provided the most widely adopted measurements of the quasar luminosity function (QLF) at z>3z>3. However, a careful re-examination of the SDSS quasar sample revealed that the SDSS quasar selection is in fact missing a significant fraction of z3z\gtrsim3 quasars at the brightest end. We have identified the purely optical color selection of SDSS, where quasars at these redshifts are strongly contaminated by late-type dwarfs, and the spectroscopic incompleteness of the SDSS footprint as the main reasons. Therefore we have designed the Extremely Luminous Quasar Survey (ELQS), based on a novel near-infrared JKW2 color cut using WISE AllWISE and 2MASS all-sky photometry, to yield high completeness for very bright (mi<18.0m_{\rm{i}} < 18.0) quasars in the redshift range of 3.0z5.03.0\leq z\leq5.0. It effectively uses random forest machine-learning algorithms on SDSS and WISE photometry for quasar-star classification and photometric redshift estimation. The ELQS will spectroscopically follow-up 230\sim 230 new quasar candidates in an area of 12000deg2\sim12000\,\rm{deg}^2 in the SDSS footprint, to obtain a well-defined and complete quasars sample for an accurate measurement of the bright-end quasar luminosity function at 3.0z5.03.0\leq z\leq5.0. In this paper we present the quasar selection algorithm and the quasar candidate catalog.Comment: 16 pages, 8 figures, 9 tables; ApJ in pres

    Self-attraction effect and correction on three absolute gravimeters

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    The perturbations of the gravitational field due to the mass distribution of an absolute gravimeter have been studied. The so called Self Attraction Effect (SAE) is crucial for the measurement accuracy, especially for the International Comparisons, and for the uncertainty budget evaluation. Three instruments have been analysed: MPG-2, FG5-238 and IMPG-02. The SAE has been calculated using a numerical method based on FEM simulation. The observed effect has been treated as an additional vertical gravity gradient. The correction (SAC) to be applied to the computed g value has been associated with the specific height level, where the measurement result is typically reported. The magnitude of the obtained corrections is of order 1E-8 m/s2.Comment: 14 pages, 8 figures, submitted to Metrologi

    The Discovery of A Luminous Broad Absorption Line Quasar at A Redshift of 7.02

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    Despite extensive efforts, only two quasars have been found at z>7z>7 to date due to a combination of low spatial density and high contamination from more ubiquitous Galactic cool dwarfs in quasar selection. This limits our current knowledge of the super-massive black hole (SMBH) growth mechanism and reionization history. In this letter, we report the discovery of a luminous quasar at z=7.021z=7.021, DELS J003836.10-152723.6 (hereafter J0038-1527), selected using photometric data from DESI Legacy imaging Survey (DELS), Pan-STARRS1 (PS1) imaging Survey, as well as Wide-field Infrared Survey Explore (WISEWISE) mid-infrared all-sky survey. With an absolute magnitude of M1450M_{1450}=-27.1 and bolometric luminosity of LBolL_{\rm Bol}=5.6×\times1013^{13} LL_\odot, J0038-1527 is the most luminous quasar known at z>7z>7. Deep optical to near infrared spectroscopic observations suggest that J0038-1527 hosts a 1.3 billion solar mass BH accreting at the Eddington limit, with an Eddington ratio of 1.25±\pm0.19. The CIV broad emission line of J0038-1527 is blue-shifted by more than 3000 km s1^{-1} to the systemic redshift. More detailed investigations of the high quality spectra reveal three extremely high velocity CIV broad absorption lines (BALs) with velocity from 0.08 to 0.14 times the speed of light and total balnicity index of more than 5000 km s1^{-1}, suggesting the presence of relativistic outflows. J0038-1527 is the first quasar found at the epoch of reionization (EoR) with such strong outflows and provides a unique laboratory to investigate AGN feedback on the formation and growth of the most massive galaxies in the early universe.Comment: ApJL in pres

    Deep structure of the Ionian Sea and Sicily Dionysus - Cruise No. M111, October 10 - November 1, 2014, Catania (Italy) – Catania (Italy)

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    Summary The origin of the Ionian Sea lithosphere and the deep structure of its margins remain a little investigated part of the Mediterranean Sea. To shed light on the plate tectonic setting in this central part of southern Europe, R/V METEOR cruise M111 set out to acquire deep penetrating seismic data in the Ionian Sea. M111 formed the core of an amphibious investigation covering the Ionian Sea and island of Sicily. A total of 153 OBS/OBH deployments using French and German instruments were successfully carried out, in addition to 12 land stations installed on Sicily, which recorded the offshore air gun shots. The aim of this onshore-offshore study is to quantify the deep geometry and architecture of the Calabria subduction zone and Ionian Sea lithosphere and to shed light on the nature of the Ionian Sea crust (oceanic crust vs. thinned continental crust). Investigating the structure of the Ionian crust and lithospheric mantle will contribute to unravel the unknown ocean-continent transition and Tethys margin. Analyzing the tectonic activity and active deformation zones is essential for understanding the subduction processes that underlie the neotectonics of the Calabrian subduction zone and earthquake hazard of the Calabria/Sicily region, especially in the vicinity of local decoupling zones

    Solar radiative transfer simulations in Saharan dust plumes: particle shapes and 3-D effect

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    Radiative fields of three-dimensional inhomogeneous Saharan dust clouds have been calculated at solar wavelength (0.6 μm) by means of a Monte Carlo radiative transfer model. Scattering properties are taken from measurements in the SAMUM campaigns, from light scattering calculations for spheroids based on the MIESCHKA code, from Mie theory for spheres and from the geometric optics method assuming irregular shaped particles. Optical properties of different projected area equivalent shapes are compared. Large differences in optical properties are found especially in the phase functions. Results of radiative transfer calculations based on the Monte Carlo method are shown exemplarily for one dust cloud simulated by the cloud resolving atmospheric circulation model LM-MUSCAT-DES. Shape-induced differences in the radiation fluxes are pronounced, for example, the domain averaged normalized radiance is about 30% lower in the case of a dust plume consisting of spheroids or irregular particles compared to spheres. The effect of net horizontal photon transport (3-D effect) on the reflected radiance fields is only notable at the largest gradients in optical thickness. For example, the reflectance at low sun position differs locally about 15% when horizontal photon transport is accounted for. ‘Sharp edges' due to 1-D calculations are smoothed out in the 3-D case

    Regenerative Potential of Platelet-Rich Fibrin in Maxillary Sinus Floor Lift Techniques: A Systematic Review

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    Background: Platelet-rich Fibrin (PRF) represents a type of autologous biomaterial investigated through the years by in vitro and in vivo studies to assess the real inductivity properties, presumed due to the growth factors presence. This systematic review aims to evaluate the efficacy of PRF in sinus lift procedures, compared and/or in addition to Deproteinized Bovine Bone Materials (DBBM) according to emerging scientific evidence. Materials and Methods: Selected databases were PubMed, Scopus, and Cochrane Library. The search strategy included the following terms: "PRF", "platelet concentrate", "autologous platelet concentrate", "platelet-rich fibrin", "bone grafts" or "DBBM", "xenografts" or "Bio-Oss", "maxillary sinus lift", "maxillary sinus elevation", "maxillary sinus augmentation". Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. Results: Four studies were included in the systematic review, evaluating clinical, histological, histomorphometric, and radiological data. Three of four studies reported no statistically significant differences between the test and control groups. In one study, the presence of Leukocyte-Platelet Rich Fibrin (L-PRF) could allow earlier implant placement, achieving the same clinical, histological, histomorphometric, and radiological results of bone regeneration at an earlier time, compared to the DBBM used Conclusions: The regenerative potential of PRF associated with DBBM resulted in a valid alternative in the bone regeneration procedure to DBBM grafts. Further new studies are needed, with more rigid protocols, to investigate the potential of platelet concentrates in sinus lift techniques and to evaluate the real inductivity properties of DBBM

    Use of two virtual dissection tables in a postgraduate oral anatomy course: feedback from the students

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    BACKGROUND: Advancements in medical education technologies transformed the teaching and learning of several disciplines, including human anatomy, which is considered the core of health sciences education. Recent technological innovations, including virtual dissection tables like the Anatomage® and SECTRA® table, provided interactive 3D models and clinical imaging that address these limitations. This study aims to evaluate the rating of two different VDTs in teaching clinical anatomy to post-graduate dental doctors, emphasizing their perceived advantages for clinical practice. METHODS: A population (N = 24) of post-graduate students in oral surgery (N = 7) and orthodontics (N = 17) were enrolled in this study. The design of the lecture included practical sessions on the Anatomage® and SECTRA® table, including cases evaluations on anatomy structures. Anonymous surveys were used to evaluate the grade of perception on the use of both VDTs. The software used for statistical calculations was GraphPad Prism version 10.4.0 (621) for Windows. RESULTS: The post-graduate students significantly positively considered the use of VDTs as very useful and user-friendly learning instruments, offering very satisfying quality of the digital images. The level of clinical self-confidence and satisfaction of the proposed teaching method lecture was considered statistically positive. CONCLUSIONS: The integration and the diversification of the anatomy teaching strategies, using innovation technologies, increase the learning processes and improve the clinical self-confidence in post-graduate dental students

    Morphological and Biological Evaluations of Human Periodontal Ligament Fibroblasts in Contact with Different Bovine Bone Grafts Treated with Low-Temperature Deproteinisation Protocol

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    Several types of deproteinised bovine bone mineral (DBBM) are available on the market, and each one is obtained with a thermic and chemical process that can differ, achieving different results. Currently, several protocols using low temperature are suggested to reduce the possible particle crystallisation during the production process. This study aimed to evaluate the biomorphological reaction of periodontal fibroblast cultures in contact with different DBBM particles treated with a low-temperature protocol (Thermagen®) and without exposure to sodium hydroxide (NaOH). Morphological evaluation was performed using light, confocal laser, and scanning electron microscopy, and the biological reaction in terms of proliferation was performed using an XTT proliferation assay at 24 h (T1), 72 h (T2), and 7 days (T3). The morphological analysis highlighted how the presence of the materials stimulated a change in the morphology of the cells into a polygonal shape, surface reactions with the thickening of the membrane, and expression of actin. In particular, the morphological changes were appreciable from T1, with a progressive increase in the considered morphological characteristics at T2 and T3 follow-ups. The proliferation assay showed a statistical significance between the different experimental materials and the negative control in T2 and T3 follow-ups. The post hoc analysis did not reveal any differences between the materials. In conclusion, the grafts obtained with the low-temperature extractions protocol and not exposed to NaOH solution showed positive morphological reactions with no differences in the sizes of particles
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