A Comparison of Three Conditional Growth Percentile Methods: Student Growth Percentiles, Percentile Rank Residuals, and a Matching Method

This article provides a brief overview and comparison of three conditional growth percentile methods; student growth percentiles, percentile rank residuals, and a nonparametric matching method. These approaches seek to describe student growth in terms of the relative percentile ranking of a student in relationship to students that had the same profile of prior achievement. It is shown that even though the methods come from a similar conceptual foundation, the methods make different assumptions and use different models to estimate growth percentiles. Reading and Mathematics data from a large-scale assessment program are used to compare the growth percentile estimates in a practical setting. Results suggested that the methods often give somewhat similar results. However, the matching method tended to provide somewhat different estimates compared to the other approaches for students that had extreme scores on the prior year test. The implications of these results for large-scale state accountability programs are discussed. Accessed 5,254 times on https://pareonline.net from November 12, 2014 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right

Characterizing unknown systematics in large scale structure surveys

Photometric large scale structure (LSS) surveys probe the largest volumes in the Universe, but are inevitably limited by systematic uncertainties. Imperfect photometric calibration leads to biases in our measurements of the density fields of LSS tracers such as galaxies and quasars, and as a result in cosmological parameter estimation. Earlier studies have proposed using cross-correlations between different redshift slices or cross-correlations between different surveys to reduce the effects of such systematics. In this paper we develop a method to characterize unknown systematics. We demonstrate that while we do not have sufficient information to correct for unknown systematics in the data, we can obtain an estimate of their magnitude. We define a parameter to estimate contamination from unknown systematics using cross-correlations between different redshift slices and propose discarding bins in the angular power spectrum that lie outside a certain contamination tolerance level. We show that this method improves estimates of the bias using simulated data and further apply it to photometric luminous red galaxies in the Sloan Digital Sky Survey as a case study.Comment: 24 pages, 6 figures; Expanded discussion of results, added figure 2; Version to be published in JCA

Создание износостойкого покрытия с использованием непрерывного и импульсного электронного луча

В настоящей работе представлены результаты исследования влияния импульсной электронной обработки и последующего отжига на структуру и твердость покрытий из хромо-ванадиевого чугуна. Покрытия были получены методом электронно-лучевой наплавки на подложке из малоуглеродистой стали. После шлифования поверхности покрытий были обработаны локальноимпульсным сфокусированным в точку электронным пучком. Результаты исследования показали, что модифицированные зоны состоят из двух фаз. Первая фаза - пересыщенный аустенит. Вторая локально распределенные в объеме модифицированной зоны зародыши эвтектики. Результаты измерений системой NanoTest показали, что модифицированные зоны имеют низкие значения твердости. Низкие значения твердости, вероятно, обусловлено наличием значительного объема пересыщенного аустенита в модифицированной зоне. Отжиг приводит к значительному увеличению твердости модифицированных зон. В результате отжига (500°С ) пересыщенный аустенит распадается. Повышение температуры отжига до 1100°С приводит к росту и коагуляции карбидной фазы модифицированных зон

Interaction of Co(II), Ni(II) and Cu(II) with dibenzo-substituted macrocyclic ligands incorporating both symmetrically and unsymmetrically arranged N, O and S donors

The synthesis and characterisation of four 17-membered, dibenzo-substituted macrocyclic ligands incorporating unsymmetrical arrangements of their N3S2, N3O2 and N3OS (two ligands) donor atoms are described; these rings complete the matrix of related macrocyclic systems incorporating both symmetric and unsymmetric donor sets reported previously. The X-ray structures of three of the new macrocycles are reported. In two of the Cu(II) structures only three of the possible five donor atoms present in the corresponding macrocyclic ligand bind to the Cu(II) site, whereas all five donors are coordinated in each of the remaining complexes. The interaction of Co(II), Ni(II) and Cu(II) with the unsymmetric macrocycle series has been investigated by potentiometric (pH) titration in 95% methanol; X-ray structures of two nickel and three copper complexes of these ligands, each exhibiting 1 : 1 (M :L) ratios, have been obtained. The results are discussed in the context of previous results for these metals with the analogous 17-membered ring systems incorporating symmetrical arrangements of their donor atoms, with emphasis being given to both the influence of the donor atom set, as well as the donor atom sequence, on the nature of the resulting complexes

Sloan Digital Sky Survey III Photometric Quasar Clustering: Probing the Initial Conditions of the Universe using the Largest Volume

The Sloan Digital Sky Survey has surveyed 14,555 square degrees of the sky, and delivered over a trillion pixels of imaging data. We present the large-scale clustering of 1.6 million quasars between z = 0.5 and z = 2.5 that have been classified from this imaging, representing the highest density of quasars ever studied for clustering measurements. This data set spans ~11,000 square degrees and probes a volume of 80(Gpc/h)^3. In principle, such a large volume and medium density of tracers should facilitate high-precision cosmological constraints. We measure the angular clustering of photometrically classified quasars using an optimal quadratic estimator in four redshift slices with an accuracy of ~25% over a bin width of l ~10 - 15 on scales corresponding to matter-radiation equality and larger (l ~ 2 - 30). Observational systematics can strongly bias clustering measurements on large scales, which can mimic cosmologically relevant signals such as deviations from Gaussianity in the spectrum of primordial perturbations. We account for systematics by employing a new method recently proposed by Agarwal et al. (2014) to the clustering of photometrically classified quasars. We carefully apply our methodology to mitigate known observational systematics and further remove angular bins that are contaminated by unknown systematics. Combining quasar data with the photometric luminous red galaxy (LRG) sample of Ross et al. (2011) and Ho et al. (2012), and marginalizing over all bias and shot noise-like parameters, we obtain a constraint on local primordial non-Gaussianity of fNL = -113+/-154 (1\sigma error). [Abridged]Comment: 35 pages, 15 figure

Poly[[tris­(μ2-4,4′-bipyridine N,N′-di­oxide)hexa­nitratodieuropium(III)] dichloro­methane disolvate]

The title one-dimensional coordination network, {[Eu2(NO3)6(C10H8N2O2)3]·2CH2Cl2}n, is isostructural with the previously reported Tb and Tl coordination networks and to its Gd analog. The EuIII cation is coordinated in a distorted tricapped trigonal-prismatic fashion by nine O atoms from three bridging 4,4′-bipyridine N,N′-dioxide ligands and three chelating nitrate anions. None of the atoms lie on a special position, but there is an inversion center located between the rings of one of the ligands. The network topology is ladder-like, and each ladder inter­acts with six neighboring ladders through C—H⋯O hydrogen bonds. The packing motif of the ladders allows for the formation of channels that run parallel to the a axis; these channels are filled with CH2Cl2 solvent mol­ecules that inter­act with the ladders through C—H⋯O hydrogen bonds