217 research outputs found
The Microlensing Properties of a Sample of 87 Lensed Quasars
Gravitational microlensing is a powerful tool for probing the physical
properties of quasar accretion disks and properties of the lens galaxy such as
its dark matter fraction and mean stellar mass. Unfortunately the number of
lensed quasars () exceeds our monitoring capabilities. Thus,
estimating their microlensing properties is important for identifying good
microlensing candidates as well as for the expectations of future surveys. In
this work we estimate the microlensing properties of a sample of 87 lensed
quasars. While the median Einstein radius crossing time scale is 20.6 years,
the median source crossing time scale is 7.3 months. Broadly speaking, this
means that on year timescales roughly half the lenses will be
quiescent, with the source in a broad demagnified valley, and roughly half will
be active with the source lying in the caustic ridges. We also found that the
location of the lens system relative to the CMB dipole has a modest effect on
microlensing timescales, and in theory microlensing could be used to confirm
the kinematic origin of the dipole. As a corollary of our study we analyzed the
accretion rate parameters in a sub-sample of 32 lensed quasars. At fixed black
hole mass, it is possible to sample a broad range of luminosities (i.e.,
Eddington factors) if it becomes feasible to monitor fainter lenses.Comment: 31 pages, 7 figures, 2 tables, corrected typos in Table 2, revised
version accepted for publication in Ap
Microalgae-bacterial biomass outperforms PN-anammox biomass for oxygen saving in continuous-flow granular reactors facing extremely low-strength freshwater aquaculture streams
The dissolved oxygen (DO) concentration in water streams is one of the most important and critical quality parameters in aquaculture farms. The main objective of this study was to evaluate the potential of two Continuous Flow Granular Reactors, one based on Partial Nitrification-Anammox biomass (Aquammox CFGR) and the other on Microalgae-Bacteria biomass (AquaMab CFGR), for improving dissolved oxygen availability in the recirculation aquaculture systems (RAS). Both reactors treated the extremely low-strength effluents from a freshwater trout farm (1.39 mg NH4 +-N/L and 7.7 mg TOC/L). The Aquammox CFGR, removed up to 68% and 100% of ammonium and nitrite, respectively, but the DO concentration in the effluent was below 1 mg O2/L while the anammox activity was not maintained. In the AquaMab CFGR, bioaugmentation of aerobic granules with microalgae was attained, producing an effluent with DO concentrations up to 9 mg O2/L and removed up to 77% and 80% of ammonium and nitrite, respectively, which is expected to reduce the aeration costs in fish farms.info:eu-repo/semantics/publishedVersio
Accretion Disk Size Measurement and Time Delays in the Lensed Quasar WFI 2033-4723
We present 13 seasons of -band photometry of the quadruply-lensed quasar
WFI 2033-4723 from the 1.3m SMARTS telescope at CTIO and the 1.2m Euler Swiss
Telescope at La Silla, in which we detect microlensing variability of
mags on a timescale of 6 years. Using a Bayesian Monte Carlo technique,
we analyze the microlensing signal to obtain a measurement of the size of this
system's accretion disk of at
, assuming a inclination angle. We
confirm previous measurements of the BC and AB time delays, and we obtain a
tentative measurement of the delay between the closely spaced A1 and A2 images
of days. We conclude
with an update to the Quasar Accretion Disk Size - Black Hole Mass Relation, in
which we confirm that the accretion disk size predictions from simple thin disk
theory are too small.Comment: 20 pages, 9 figures, Accepted by Ap
Nitrogen removal from freshwater aquaculture effluents: sequencing versus continuous granular sludge reactors
info:eu-repo/semantics/publishedVersio
Granular sludge technology for valorization of water use: from high to low strength effluents in aquaculture
info:eu-repo/semantics/publishedVersio
Microalgae-bacterial biomass outperforms PN-anammox biomass for oxygen saving in continuous-flow granular reactors facing extremely low-strength freshwater aquaculture streams
The dissolved oxygen (DO) concentration in water streams is one of the most important and critical quality parameters in aquaculture farms. The main objective of this study was to evaluate the potential of two Continuous Flow Granular Reactors, one based on Partial Nitrification-Anammox biomass (Aquammox CFGR) and the other on Microalgae-Bacteria biomass (AquaMab CFGR), for improving dissolved oxygen availability in the recirculation aquaculture systems (RAS). Both reactors treated the extremely low-strength effluents from a freshwater trout farm (1.39 mg NH4+-N/L and 7.7 mg TOC/L). The Aquammox CFGR, removed up to 68% and 100% of ammonium and nitrite, respectively, but the DO concentration in the effluent was below 1 mg O2/L while the anammox activity was not maintained. In the AquaMab CFGR, bioaugmentation of aerobic granules with microalgae was attained, producing an effluent with DO concentrations up to 9 mg O2/L and removed up to 77% and 80% of ammonium and nitrite, respectively, which is expected to reduce the aeration costs in fish farmsThe authors would like to thank the EU, the Spanish Government (AEI) (PCIN-2017-047) and Fundação para a Ciência e Tecnologia (FCT) (Water JPI/0003/2016) for funding, in the frame of the collaborative international Consortium AQUAVAL financed under the ERA-NET WaterWorks2015 Cofunded Call. This ERA-NET is an integral part of the 2016 Joint Activities developed by the Water Challenges for a Changing World Joint Programme Initiative (Water JPI) and the CDTI (Centro para Desarrollo Tecnológico Industrial, E.P.E., Spain). Authors also thank the Spanish Government (AEI) for funding in the frame of the project TREASURE (CTQ 2017-83225-C2-1-R) and the FCT for funding in the frame of the project UIDB/50016/2020. S. Santorio, A. Val del Rio and A. Mosquera-Corral belong to the Galician Competitive Research Groups (GRC)_ED431C-2021/37 co-funded by FEDER (EU)S
Disruption of NIPBL/Scc2 in Cornelia de Lange Syndrome provokes cohesin genome-wide redistribution with an impact in the transcriptome
Cornelia de Lange syndrome (CdLS) is a rare disease affecting multiple organs and systems during development. Mutations in the cohesin loader, NIPBL/Scc2, were first described and are the most frequent in clinically diagnosed CdLS patients. The molecular mechanisms driving CdLS phenotypes are not understood. In addition to its canonical role in sister chromatid cohesion, cohesin is implicated in the spatial organization of the genome. Here, we investigate the transcriptome of CdLS patient-derived primary fibroblasts and observe the downregulation of genes involved in development and system skeletal organization, providing a link to the developmental alterations and limb abnormalities characteristic of CdLS patients. Genome-wide distribution studies demonstrate a global reduction of NIPBL at the NIPBL-associated high GC content regions in CdLS-derived cells. In addition, cohesin accumulates at NIPBL-occupied sites at CpG islands potentially due to reduced cohesin translocation along chromosomes, and fewer cohesin peaks colocalize with CTCF
Further Evidence that Quasar X-Ray Emitting Regions Are Compact: X-Ray and Optical Microlensing in the Lensed Quasar Q J0158-4325
We present four new seasons of optical monitoring data and six epochs of
X-ray photometry for the doubly-imaged lensed quasar Q J0158-4325. The
high-amplitude, short-period microlensing variability for which this system is
known has historically precluded a time delay measurement by conventional
methods. We attempt to circumvent this limitation by application of a Monte
Carlo microlensing analysis technique, but we are only able to prove that the
delay must have the expected sign (image A leads image B). Despite our failure
to robustly measure the time delay, we successfully model the microlensing at
optical and X-ray wavelengths to find a half light radius for soft X-ray
emission log(r_{1/2,X,soft}/cm) = 14.3^{+0.4}_{-0.5}, an upper limit on the
half-light radius for hard X-ray emission log(r_{1/2,X,hard}/cm) <= 14.6 and a
refined estimate of the inclination-corrected scale radius of the optical
R-band (rest frame 3100 Angstrom) continuum emission region of log(r_s/cm) =
15.6+-0.3.Comment: 9 pages, 6 figures, submitted to Ap
Structure of crystalline and amorphous materials in the NASICON system Na<sub>1+x</sub>Al<sub>x</sub>Ge<sub>2- x</sub>(PO<sub>4</sub>)<sub>3</sub>
The structure of crystalline and amorphous materials in the sodium (Na) super-ionic conductor system Na1+xAlxGe2-x(PO4)3 with x = 0, 0.4, and 0.8 was investigated by combining (i) neutron and x-ray powder diffraction and pair-distribution function analysis with (ii) 27Al and 31P magic angle spinning (MAS) and 31P/23Na double-resonance nuclear magnetic resonance (NMR) spectroscopy. A Rietveld analysis of the powder diffraction patterns shows that the x = 0 and x = 0.4 compositions crystallize into space group-type R3¯, whereas the x = 0.8 composition crystallizes into space group-type R3¯c. For the as-prepared glass, the pair-distribution functions and 27Al MAS NMR spectra show the formation of sub-octahedral Ge and Al centered units, which leads to the creation of non-bridging oxygen (NBO) atoms. The influence of these atoms on the ion mobility is discussed. When the as-prepared glass is relaxed by thermal annealing, there is an increase in the Ge and Al coordination numbers that leads to a decrease in the fraction of NBO atoms. A model is proposed for the x = 0 glass in which super-structural units containing octahedral Ge(6) and tetrahedral P(3) motifs are embedded in a matrix of tetrahedral Ge(4) units, where superscripts denote the number of bridging oxygen atoms. The super-structural units can grow in size by a reaction in which NBO atoms on the P(3) motifs are used to convert Ge(4) to Ge(6) units. The resultant P(4) motifs thereby provide the nucleation sites for crystal growth via a homogeneous nucleation mechanism. </p
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