The Dark Energy Spectroscopic Instrument (DESI) will precisely constrain cosmic expansion and the growth of structure by collecting \(\sim\)40 million extra-galactic redshifts across \(\sim\)80\% of ...cosmic history and one third of the sky. The Emission Line Galaxy (ELG) sample, which will comprise about one-third of all DESI tracers, will be used to probe the Universe over the \(0.6 < z < 1.6\) range, which includes the \(1.1<z<1.6\) range, expected to provide the tightest constraints. We present the target selection of the DESI SV1 Survey Validation and Main Survey ELG samples, which relies on the Legacy Surveys imaging. The Main ELG selection consists of a \(g\)-band magnitude cut and a \((g-r)\) vs.\ \((r-z)\) color box, while the SV1 selection explores extensions of the Main selection boundaries. The Main ELG sample is composed of two disjoint subsamples, which have target densities of about 1940 deg\(^{-2}\) and 460 deg\(^{-2}\), respectively. We first characterize their photometric properties and density variations across the footprint. Then we analyze the DESI spectroscopic data obtained since December 2020 during the Survey Validation and the Main Survey up to December 2021. We establish a preliminary criterion to select reliable redshifts, based on the \oii~flux measurement, and assess its performance. Using that criterion, we are able to present the spectroscopic efficiency of the Main ELG selection, along with its redshift distribution. We thus demonstrate that the the main selection with higher target density sample should provide more than 400 deg\(^{-2}\) reliable redshifts in both the \(0.6<z<1.1\) and the \(1.1<z<1.6\) ranges.
A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) of the optical spectroscopic data to quantify key survey metrics. In ...this paper we present results from VI of the quasar survey using deep coadded SV spectra. We show that the majority (~70%) of the main-survey targets are spectroscopically confirmed as quasars, with ~16% galaxies, ~6% stars, and ~8% low-quality spectra lacking reliable features. A non-negligible fraction of the quasars are misidentified by the standard spectroscopic pipeline but we show that the majority can be recovered using post-pipeline "afterburner" quasar-identification approaches. We combine these "afterburners" with our standard pipeline to create a modified pipeline to improve the overall quasar yield. At the depth of the main DESI survey both pipelines achieve a good-redshift purity (reliable redshifts measured within 3000 km/s) of ~99%; however, the modified pipeline recovers ~94% of the visually inspected quasars, as compared to ~86% from the standard pipeline. We demonstrate that both pipelines achieve an median redshift precision and accuracy of ~100 km/s and ~70 km/s, respectively. We constructed composite spectra to investigate why some quasars are missed by the standard spectroscopic pipeline and find that they are more host-galaxy dominated (i.e., distant analogs of "Seyfert galaxies") and/or dust reddened than the standard-pipeline quasars. We also show example spectra to demonstrate the overall diversity of the DESI quasar sample and provide strong-lensing candidates where two targets contribute to a single spectrum.
Mineral crystals with specific surface texture have been grown by a templating mechanism from a lyotropic liquid-crystalline phase. This experimental system is important in understanding ...mineralization in ordered organic media, a phenomenon of importance in biology and possibly in biomaterials technology as well. The first step in the process involves the doping of a mesophase with precursor ions for the mineral phase with little disruption of the order parameter. Growth of the mineral crystals is then induced by establishing interfacial contact between mesophases doped with different precursor ions. In the system studied here, mineralization occurs at the interface as a result of diffusion of calcium and phosphate ions toward regions of lower concentration. Characterization of the precipitate formed at the interface by X-ray as well as electron diffraction, elemental analysis, and transmission and scanning electron microscopy has revealed the formation of single crystals of brushite (CaHPO4·2H2O) with triangular and platelike morphology. Most importantly, these crystals exhibited longitudinal striations on their surface which are believed to be due a templating effect from the liquid-crystalline phase. The striations are most likely an imprint of the preferred orientation of cylindrical molecular assemblies in the hexagonal mesophase.
Objectives: Poisoned patients are at risk of impaired ventilation in many situations. The purpose of this descriptive study was to investigate the impact of educational workshops on nurses' ...knowledge, confidence, and attitude in taking care of poisoned patients. Materials and Methods: This descriptive study was performed on 60 nursing staff in the intensive care unit (ICU) for poisoned patients in Imam Reza (p) hospital, Mashhad, Iran. Data was gathered by a researcher-designed questionnaire. Studied scales included perceived importance and novelty of educational meeting, matching with professional and educational needs, illustration of practical and knowledge weaknesses and strength and finally satisfaction in holding regular workshops annually. Two, half day workshops were held and various items were taught with various methods. The knowledge of participants was assessed by pretests and post-tests consisting of 12 items related to workshop topics. The impact of these educational meetings was evaluated and the results were analyzed by the SPSS software. Results: According to the results, workshops improved awareness of nurses about their weakness and strength points, professional knowledge and their interest and attention; likewise all participants had the same opinion about a strong need to hold similar workshops more than once and preferably 2 to 3 times annually. Conclusion: It seems that short educational courses in small groups for reviewing the old data and recent findings in the context of critical care are useful in order to promote the knowledge and skills of ICU staff in taking care of poisoned patients
Computer models for the movement and water delivery of low pressure center pivot and linear-move systems with furrow drops were used to compute water distribution uniformities. The models for small, ...3-span, 170-m systems compared satisfactorily with field results. The computed results for 396 m systems had lower uniformities than for the 170 m systems. Uniformities were lowest for furrow-check spacings of 0.5 m or less. As system speed increased, uniformities with short check spacings increased. At check spacings of 3 m or greater, speed had no effect with the center pivot but varied over a 10% range for the linear move. To obtain a uniformity coefficient of 0.8, check spacings needed to be at least 2 m. Uniformities were greatly improved if the alignment angles between spans, which controlled tower movements, were reduced from 0.7 degrees to 0.4 degrees or 0.25 degrees. However, this caused more frequent movement of the center towers which requires more expensive equipment
We present the most precise estimate to date of the clustering of quasars on very small scales, based on a sample of 47 binary quasars with magnitudes of \(g<20.85\) and proper transverse separations ...of \(\sim 25\,h^{-1}\)\,kpc. Our sample of binary quasars, which is about 6 times larger than any previous spectroscopically confirmed sample on these scales, is targeted using a Kernel Density Estimation technique (KDE) applied to Sloan Digital Sky Survey (SDSS) imaging over most of the SDSS area. Our sample is "complete" in that all of the KDE target pairs with \(17.0 \lesssim R \lesssim 36.2\,h^{-1}\)\,kpc in our area of interest have been spectroscopically confirmed from a combination of previous surveys and our own long-slit observational campaign. We catalogue 230 candidate quasar pairs with angular separations of \(<8\arcsec\), from which our binary quasars were identified. We determine the projected correlation function of quasars (\(\bar W_{\rm p}\)) in four bins of proper transverse scale over the range \(17.0 \lesssim R \lesssim 36.2\,h^{-1}\)\,kpc. The implied small-scale quasar clustering amplitude from the projected correlation function, integrated across our entire redshift range, is \(A=24.1\pm3.6\) at \(\sim 26.6 ~h^{-1}\)\,kpc. Our sample is the first spectroscopically confirmed sample of quasar pairs that is sufficiently large to study how quasar clustering evolves with redshift at \(\sim 25 ~h^{-1}\) kpc. We find that empirical descriptions of how quasar clustering evolves with redshift at \(\sim 25 ~h^{-1}\) Mpc also adequately describe the evolution of quasar clustering at \(\sim 25 ~h^{-1}\) kpc.
We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one AGN (NGC 3227) from a 2014 campaign. Our main goals are (1) to ...determine the black hole masses from continuum-Hbeta reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure Hbeta time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity dependent Hbeta lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.
We present a measurement of the quasar luminosity function in the range 0.68<z<4 down to extinction corrected magnitude g_dered=22.5, using a simple and well understood target selection technique ...based on the time-variability of quasars. The completeness of our sample was derived directly from a control sample of quasars, without requiring complex simulations of quasar light-curves or colors. A total of 1877 quasar spectra were obtained from dedicated programs on the Sloan telescope (as part of the SDSS-III/BOSS survey) and on the Multiple Mirror Telescope. They allowed us to derive the quasar luminosity function. It agrees well with previously published results in the redshift range 0.68<z<2.6. Our deeper data allow us to extend the measurement to z=4. We measured quasar densities to g_dered<22.5, obtaining 30 QSO per deg^2 at z<1, 99 QSO per deg^2 for 1<z<2.15, and 47 QSO per deg^2 at z>2.15. Using pure luminosity evolution models, we fitted our LF measurements, and predicted quasar number counts as a function of redshift and observed magnitude. These predictions are useful inputs for future cosmology surveys such as those relying on the observation of quasars to measure baryon acoustic oscillations.
Furrow Irrigation Using Canal Side Weirs Eftekharzadeh, Shahriar; Clemmens, Albert J; Fangmeier, Delmar D
Journal of irrigation and drainage engineering,
05/1987, Letnik:
113, Številka:
2
Journal Article
Recenzirano
The potential of canal side weirs for uniform water delivery to irrigation furrows and system flexibility is assessed. Weir discharge uniformity is affected by: (1) Canal velocity and weir entrance ...conditions; (2) variations in weir crest construction elevations; and (3) variations in water surface elevations along the distribution canal. For sharp-entranced weirs, model studies show that the decrease in canal flow velocity down a typical distribution reach can result in an increase in weir discharge up to 15%. This velocity effect is significantly dampened by using a streamlined entrance to the weir. Field data on weir crest elevations have a standard deviation of about 3 mm, which translates into 6-8% weir discharge variation at normal discharge settings. A computer model of distribution canal flows indicates weir discharge uniformity is improved by shortening the length of the reach, reducing the required weir discharge setting, and increasing canal size. A design guideline is developed for the system.
Polyglutamine (polyQ) tracts are regions of low sequence complexity frequently found in transcription factors. Tract length often correlates with transcriptional activity and expansion beyond ...specific thresholds in certain human proteins is the cause of polyQ disorders. To study the structural basis of the association between tract length, transcriptional activity and disease, we addressed how the conformation of the polyQ tract of the androgen receptor, associated with spinobulbar muscular atrophy (SBMA), depends on its length. Here we report that this sequence folds into a helical structure stabilized by unconventional hydrogen bonds between glutamine side chains and main chain carbonyl groups, and that its helicity directly correlates with tract length. These unusual hydrogen bonds are bifurcate with the conventional hydrogen bonds stabilizing α-helices. Our findings suggest a plausible rationale for the association between polyQ tract length and androgen receptor transcriptional activity and have implications for establishing the mechanistic basis of SBMA.
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