Equidistribution of Heegner Points and Ternary Quadratic Forms

We prove new equidistribution results for Galois orbits of Heegner points with respect to reduction maps at inert primes. The arguments are based on two different techniques: primitive representations of integers by quadratic forms and distribution relations for Heegner points. Our results generalize one of the equidistribution theorems established by Cornut and Vatsal in the sense that we allow both the fundamental discriminant and the conductor to grow. Moreover, for fixed fundamental discriminant and variable conductor, we deduce an effective surjectivity theorem for the reduction map from Heegner points to supersingular points at a fixed inert prime. Our results are applicable to the setting considered by Kolyvagin in the construction of the Heegner points Euler system

Word reading strategies: A replication and follow up intervention

The first stage of this study involved a replication of the cluster analysts procedures used by Freebody and Byrne (1988) to classify Year 2 readers according to their word reading strategies based on lists of irregular and pseudowords. A four-cluster-solution produced three groups similar to those reported by Freebody and Byrne (1988), and a fourth group which could not be classified using their criteria. A three-cluster-solution produced a more parsimonious interpretation, with these groups meeting the criteria for LB (low on both Irregular and pseudowords), HB (high on both), and Phoenician readers (average or above on pseudoword, low on irregular words). There was no evidence of a discrete group of Chinese readers (low on pseudowords, average or above average on irregular words). These results were interpreted in the context of stage models of reading development. A replication was carried out of Freebody and Byrnes (1988) examination of differences in the phonemic awareness abilities of the subjects grouped on the basis of the four-cluster-solution. Subjects were tested using the initial-consonant-elision and the final-consonant-matching tasks. Three additional phonemic awareness tasks were also used: telescoping, segmenting and rhyming. Results showed unacceptable reliability of the telescoping, segmenting and final consonant-matching tasks, coupled with ceiling effects for telescoping and segmenting. Consequently, only the results from the combined initial-consonant-elision and final-consonant matching tasks, and the rhyming tasks were used. Consistent with the findings of Freebody and Byrne (1988), the LB group showed significantly lower phonemic awareness than the other groups combined, the HB group showed the reverse outcome. This finding is consistent with previous research that has shown a relationship between phonemic awareness and reading achievement. There was a significant difference for the remaining two groups, but only on the rhyming task in favour of the Phoenician readers, reflecting their ability to recognise sound patterns within words. The second stage of the study consisted of a single subject design investigation in which baseline data was collected for six (LB) subjects. As the requirement of stable and level baselines was not met for five of the six subjects, the decision was made to implement a changing criterion design with the other subject. He was given explicit Instruction In which he was taught to discriminate between the letters he previously confused, and the strategy of sounding out regular word types without stopping between sounds. His daily data showed that by the end of the Intervention phase, consisting of 16 half-hour teaching sessions, he had reached criteria in reading mixed regular word types. In addition, his post-test score on the pseudoword list indicated that he would now qualify as a Phoenician reader. Further research is required to investigate the extent to which changes In word reading strategy can be brought about by Instruction

Impact of a comprehensive prevention programme aimed at reducing incivility and verbal violence against healthcare workers in a French ophthalmic emergency department: an interrupted time-series study.

Primary prevention, comprising patient-oriented and environmental interventions, is considered to be one of the best ways to reduce violence in the emergency department (ED). We assessed the impact of a comprehensive prevention programme aimed at preventing incivility and verbal violence against healthcare professionals working in the ophthalmology ED (OED) of a university hospital. The programme was designed to address long waiting times and lack of information. It combined a computerised triage algorithm linked to a waiting room patient call system, signage to assist patients to navigate in the OED, educational messages broadcast in the waiting room, presence of a mediator and video surveillance. All patients admitted to the OED and those accompanying them. Single-centre prospective interrupted time-series study conducted over 18 months. Violent acts self-reported by healthcare workers committed by patients or those accompanying them against healthcare workers. Waiting time and length of stay. There were a total of 22 107 admissions, including 272 (1.4%) with at least one act of violence reported by the healthcare workers. Almost all acts of violence were incivility or verbal harassment. The rate of violence significantly decreased from the pre-intervention to the intervention period (24.8, 95% CI 20.0 to 29.5, to 9.5, 95% CI 8.0 to 10.9, acts per 1000 admissions, p<0.001). An immediate 53% decrease in the violence rate (incidence rate ratio=0.47, 95% CI 0.27 to 0.82, p=0.0121) was observed in the first month of the intervention period, after implementation of the triage algorithm. A comprehensive prevention programme targeting patients and environment can reduce self-reported incivility and verbal violence against healthcare workers in an OED. NCT02015884

Thermodynamic and Transport Properties of CeMg2Cu9 under Pressure

We report the transport and thermodynamic properties under hydrostatic pressure in the antiferromagnetic Kondo compound CeMg2Cu9 with a two-dimensional arrangement of Ce atoms. Magnetic specific heat Cmag(T) shows a Schottky-type anomaly around 30 K originating from the crystal electric field (CEF) splitting of the 4f state with the first excited level at \Delta_{1}/kB = 58 K and the second excited level at \Delta_{2}/kB = 136 K from the ground state. Electric resistivity shows a two-peaks structure due to the Kondo effect on each CEF level around T_{1}^{max} = 3 K and T_{2}^{max} = 40 K. These peaks merge around 1.9 GPa with compression. With increasing pressure, Neel temperature TN initially increases and then change to decrease. TN finally disappears at the quantum critical point Pc = 2.4 GPa.Comment: 10 pages, 6 figure

Magnetocrystalline Anisotropy in a Single Crystal of CeNiGe2

We report measurements on single crystals of orthorhombic CeNiGe2, which is found to exhibit highly anisotropic magnetic and transport properties. The magnetization ratio M(H//b)/M(H^b) at 2 K is observed to be about 18 at 4 T and the electrical resistivity ratio r//b/r^b is about 70 at room temperature. It is confirmed that CeNiGe2 undergoes two-step antiferromagnetic transition at 4 and 3 K, as reported for polycrystalline samples. The application of magnetic field along the b axis (the easy magnetization axis) stabilizes a ferromagnetic correlation between the Ce ions and enhances the hopping of carriers. This results in large negative magnetoresistance along the b axis.Comment: 24 pages, including 9 figure

Specific heat of Ce_{0.8}La_{0.2}Al_{3} in magnetic fields: a test of the anisotropic Kondo picture

The specific heat C of Ce_{0.8}La_{0.2}Al_{3} has been measured as a function of temperature T in magnetic fields up to 14 T. A large peak in C at 2.3 K has recently been ascribed to an anisotropic Kondo effect in this compound. A 14-T field depresses the temperature of the peak by only 0.2 K, but strongly reduces its height. The corresponding peak in C/T shifts from 2.1 K at zero field to 1.7 K at 14 T. The extrapolated specific heat coefficient C/T(T->0) increases with field over the range studied. We show that these trends are inconsistent with the anisotropic Kondo model.Comment: 4 pages, 5 figures, ReVTeX + eps

Signatures of valence fluctuations in CeCu2Si2 under high pressure

Simultaneous resistivity and a.c.-specific heat measurements have been performed under pressure on single crystalline CeCu2Si2 to over 6 GPa in a hydrostatic helium pressure medium. A series of anomalies were observed around the pressure coinciding with a maximum in the superconducting critical temperature, $T_c^{max}$. These anomalies can be linked with an abrupt change of the Ce valence, and suggest a second quantum critical point at a pressure $P_v \simeq 4.5$ GPa, where critical valence fluctuations provide the superconducting pairing mechanism, as opposed to spin fluctuations at ambient pressure. Such a valence instability, and associated superconductivity, is predicted by an extended Anderson lattice model with Coulomb repulsion between the conduction and f-electrons. We explain the T-linear resistivity found at $P_v$ in this picture, while other anomalies found around $P_v$ can be qualitatively understood using the same model.Comment: Submitted to Phys. Rev.

Kondo engineering : from single Kondo impurity to the Kondo lattice

In the first step, experiments on a single cerium or ytterbium Kondo impurity reveal the importance of the Kondo temperature by comparison to other type of couplings like the hyperfine interaction, the crystal field and the intersite coupling. The extension to a lattice is discussed. Emphasis is given on the fact that the occupation number $n_f$ of the trivalent configuration may be the implicit key variable even for the Kondo lattice. Three $(P, H, T)$ phase diagrams are discussed: CeRu$_2$Si$_2$, CeRhIn$_5$ and SmS

Quantitative localized proton-promoted dissolution kinetics of calcite using scanning electrochemical microscopy (SECM)

Scanning electrochemical microscopy (SECM) has been used to determine quantitatively the kinetics of proton-promoted dissolution of the calcite (101̅4) cleavage surface (from natural “Iceland Spar”) at the microscopic scale. By working under conditions where the probe size is much less than the characteristic dislocation spacing (as revealed from etching), it has been possible to measure kinetics mainly in regions of the surface which are free from dislocations, for the first time. To clearly reveal the locations of measurements, studies focused on cleaved “mirror” surfaces, where one of the two faces produced by cleavage was etched freely to reveal defects intersecting the surface, while the other (mirror) face was etched locally (and quantitatively) using SECM to generate high proton fluxes with a 25 μm diameter Pt disk ultramicroelectrode (UME) positioned at a defined (known) distance from a crystal surface. The etch pits formed at various etch times were measured using white light interferometry to ascertain pit dimensions. To determine quantitative dissolution kinetics, a moving boundary finite element model was formulated in which experimental time-dependent pit expansion data formed the input for simulations, from which solution and interfacial concentrations of key chemical species, and interfacial fluxes, could then be determined and visualized. This novel analysis allowed the rate constant for proton attack on calcite, and the order of the reaction with respect to the interfacial proton concentration, to be determined unambiguously. The process was found to be first order in terms of interfacial proton concentration with a rate constant k = 6.3 (± 1.3) × 10–4 m s–1. Significantly, this value is similar to previous macroscopic rate measurements of calcite dissolution which averaged over large areas and many dislocation sites, and where such sites provided a continuous source of steps for dissolution. Since the local measurements reported herein are mainly made in regions without dislocations, this study demonstrates that dislocations and steps that arise from such sites are not needed for fast proton-promoted calcite dissolution. Other sites, such as point defects, which are naturally abundant in calcite, are likely to be key reaction sites