Synthesis of a new tetradentate phosphine and its coordination chemistry with group 10 metals

Phosphines have been used extensively as ligands for transition metals. By altering the number and the spatial arrangement of the phosphorus atoms, one can significantly affect the character of the coordinated metal ion. A tetradentate phosphine (1) has been synthesized which is unique in its steric and geometric constraints.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) The carbon backbone of 1 obstructs octahedral coordination and should favor square planar and square pyramidal geometries for four and five coordinate complexes, respectively;The coordination chemistry of 1 has been investigated with Group 10 metals. Three modes of coordination have been observed for 1. The dinuclear complex (PdCl[subscript]2)[subscript]2(1), contains two six membered chelate rings and is formed by reaction of 1 and (PhCN)[subscript]2PdCl[subscript]2 in benzene. Further reaction of the dinuclear complex with 1 yields the mononuclear dication, ((solvent)Pd(1)) Cl[subscript]2. In the presence of water, and O[subscript]2, a dimethylsulfoxide solution of ((solvent)Pd(1)) Cl[subscript]2 reacts to form dimethylsulfone and a Pd product in which two arms of the phosphine remain coordinated, and two are oxidized and are dissociated. When chloride is replaced with a non-coordinating anion, dimethylsulfoxide is catalytically oxidized to dimethylsulfone;Attempts to prepare the analogous Ni(II) and Pt(II) complexes yielded fewer results. Formation of (Ni(1)) (ClO[subscript]4)[subscript]2 was achieved by the reaction of 1 with anhydrous Ni(ClO[subscript]4)[subscript]2. Reaction of 1 with Pt(II) salts and reagents generated insoluble polymers with the exception of CODPtI[subscript]2 which resulted in the reduction of Pt

Validity and sensitivity of the phonics screening check : implications for practice

This is an Open Access article made available under the terms of the Creative Commons Attribution 3.0 Unported (CC BY 3.0) license https://creativecommons.org/licenses/by/3.0/ , which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Background: Introduced in June 2012, the phonics screening check aims to assess whether 6-year-old children are meeting an appropriate standard in phonic decoding and to identify children struggling with phonic skills. Aims: We investigated whether the check is a valid measure of phonic skill and is sensitive in identifying children at risk of reading difficulties. Sample: We obtained teacher assessments of phonic skills for 292 six-year-old children and additional psychometric data for 160 of these children. Methods: Teacher assessment data were accessed from schools via the local authority; psychometric tests were administered by researchers shortly after the phonics screening check. Results: The check was strongly correlated with other literacy skills and was sensitive in identifying at-risk readers. So too were teacher judgements of phonics. Conclusions: Although the check fulfils its aims, we argue that resources might be better focused on training and supporting teachers in their ongoing monitoring of phonics.Peer reviewe

Using monodromy to recover symmetries of polynomial systems

Galois/monodromy groups attached to parametric systems of polynomial equations provide a method for detecting the existence of symmetries in solution sets. Beyond the question of existence, one would like to compute formulas for these symmetries, towards the eventual goal of solving the systems more efficiently. We describe and implement one possible approach to this task using numerical homotopy continuation and multivariate rational function interpolation. We describe additional methods that detect and exploit a priori unknown quasi-homogeneous structure in symmetries. These methods extend the range of interpolation to larger examples, including applications with nonlinear symmetries drawn from vision and robotics.Comment: Extended journal version of conference paper published at ISSAC 202

Trifocal Relative Pose from Lines at Points and its Efficient Solution

We present a new minimal problem for relative pose estimation mixing point features with lines incident at points observed in three views and its efficient homotopy continuation solver. We demonstrate the generality of the approach by analyzing and solving an additional problem with mixed point and line correspondences in three views. The minimal problems include correspondences of (i) three points and one line and (ii) three points and two lines through two of the points which is reported and analyzed here for the first time. These are difficult to solve, as they have 216 and - as shown here - 312 solutions, but cover important practical situations when line and point features appear together, e.g., in urban scenes or when observing curves. We demonstrate that even such difficult problems can be solved robustly using a suitable homotopy continuation technique and we provide an implementation optimized for minimal problems that can be integrated into engineering applications. Our simulated and real experiments demonstrate our solvers in the camera geometry computation task in structure from motion. We show that new solvers allow for reconstructing challenging scenes where the standard two-view initialization of structure from motion fails.Comment: This material is based upon work supported by the National Science Foundation under Grant No. DMS-1439786 while most authors were in residence at Brown University's Institute for Computational and Experimental Research in Mathematics -- ICERM, in Providence, R