An Investigative Approach to Teaching Mathematics: Excitement and Concerns of K-8 Preservice Teachers

Following from the recommendations of the National Council of Teachers of Mathematics, an Investigative Approach (IA) to teaching mathematics encourages students to explore real-world problems through hands-on activities instead of focusing on rote memorization of facts, formulas, and procedures. This paper discusses thirty-two K-8 preservice teachers‘ responses to questions regarding excitements and concerns about using this method of teaching. Although most preservice teachers are excited about the prospects of using this approach in their future classrooms, some exhibit hesitations related to concerns about time constraints and their own math abilities. A mathematics methods course presently being taught that is centered around the ideas of IA is discussed, and recommendations for the use of IA in preservice math methods courses to help teachers overcome these concerns are made

The chemistry of Pseudocyphellaria impressa S. Lat. in New Zealand

As part of a detailed study of the nomenclature and taxonomy of the New Zealand species of Pseudocyphellaria it has been noted that the chemistry of the P. impressa (Hook & Taylor) Vainio aggregate, that is species with a markedly faveolate (honeycomb- like) upper surface and a green algal phycobiont, is particularly complex. The 45 lichen substances detected fall into four distinct groupings, here designated as 'Codings'. The aim of this contribution is to investigate suitable methods for revealing this chemical assemblage by t.l.c. and, as far as is currently possible, to identify the range of substances. No conscious attempt is made to assign the four chemical Codings to particular taxa or species groupings; the taxonomy of the group will be discussed elsewhere. The four Codings proved to be remarkably uniform and constant considering the range and number of substances involved; such variation that occurred was only in the presence and concentration of accessory substances. Although this work only concerns New Zealand material, similar patterns occur in related taxa of the group present in southern South America, south-east Australia and Tasmania

Structure determination of new algal toxins using NMR methods

Shellfish are considered a delicacy by many consumers. In NZ, as in many overseas countries, there is a now thriv¬ing shellfish industry servicing both domestic and inter-national markets. Periodically shellfish accumulate harm¬ful levels of a variety of algal toxins, including domoic acid, yessotoxins, pectenotoxins and brevetoxins. When this occurs, regulatory authorities may impose harvesting closures which have a consequential economic impact on both farmers and staff employed to harvest and market shellfish products

Driving extreme variability: The evolving corona and evidence for jet launching in Markarian 335

Variations in the X-ray emission from the narrow line Seyfert 1 galaxy, Markarian 335 (Mrk 335), are studied on both long and short timescales through observations made between 2006 and 2013 with XMM-Newton, Suzaku and NuSTAR. Changes in the geometry and energetics of the corona that give rise to this variability are inferred through measurements of the relativistically blurred reflection seen from the accretion disc. On long timescales, we find that during the high flux epochs the corona has expanded, covering the inner regions of the accretion disc out to a radius of 26(-7,+10)rg. The corona contracts to within 12rg and 5rg in the intermediate and low flux epochs, respectively. While the earlier high flux observation made in 2006 is consistent with a corona extending over the inner part of the accretion disc, a later high flux observation that year revealed that the X-ray source had become collimated into a vertically-extended jet-like corona and suggested relativistic motion of material upward. On short timescales, we find that an X-ray flare during a low flux epoch in 2013 corresponded to a reconfiguration from a slightly extended corona to one much more compact, within just 2~3rg of the black hole. There is evidence that during the flare itself, the spectrum softened and the corona became collimated and slightly extended vertically as if a jet-launching event was aborted. Understanding the evolution of the X-ray emitting corona may reveal the underlying mechanism by which the luminous X-ray sources in AGN are powered.Comment: 21 pages, 9 figures. Accepted for publication in MNRA

Negative dynamic conductance from photon-assisted tunneling in superconducting junctions

We show that a superconductor-insulator-superconductor (SIS) junction may exhibit regions of negative dynamic conductance if it is irradiated by a time-varying signal source which deviates from the conventionally treated constant ac voltage limit. This phenomenon reflects the strong dependence of the junction absorption cross section upon dc bias voltage. Analytic estimates for the magnitude of the negative conductance and its impact upon the frequency down conversion process are obtained in the constant ac current limit

Providing Real-World Experiences: the Virginia Tech Externship for Mathematics Specialists

We describe the structure and implementation of the yearlong Externship experience associated with the Mathematics Specialist program at Virginia Polytechnic Institute & State University (Virginia Tech). We discuss the assignments and experiences included in the Externship, the alignment of those experiences with the job description developed by the Virginia Mathematics and Science Coalition Task Force, and teacher comments on the effectiveness of their Externship experiences [1]

Further nomenclature and chemical notes on Pseudocyphellaria in New Zealand

Nomenclatural notes on the following taxa are provided: Pseudocyphellaria billardierii, P. carpoloma, P. faveolata, P. rufovirescens and P. subvariabilis. Detailed chemical profiles are given for all described species of Pseudocyphellaria in New Zealand. Pseudocyphellaria ardesiaca, P. degelii, P. durietzii, P. fimbriata, P. fimbriatoides, P. gretae, P. knightii, P. maculata and P. sericeofulva spp. nov. are described for the first time

Case Report: Color as a Therapeutic Intervention

Peer reviewedFinal Accepted Versio

Polarizability of molecular hydrogen

Static dipole electric polarizabilities of molecular hydroge

Probing the geometry and motion of AGN coronae through accretion disc emissivity profiles

To gain a better understanding of the inner disc region that comprises active galactic nuclei it is necessary to understand the pattern in which the disc is illuminated (the emissivity profile) by X-rays emitted from the continuum source above the black hole (corona). The differences in the emissivity profiles produced by various corona geometries are explored via general relativistic ray tracing simulations. Through the analysis of various parameters of the geometries simulated it is found that emissivity profiles produced by point source and extended geometries such as cylindrical slabs and spheroidal coronae placed on the accretion disc are distinguishable. Profiles produced by point source and conical geometries are not significantly different, requiring an analysis of reflection fraction to differentiate the two geometries. Beamed point and beamed conical sources are also simulated in an effort to model jet-like coronae, though the differences here are most evident in the reflection fraction. For a point source we determine an approximation for the measured reflection fraction with the source height and velocity. Simulating spectra from the emissivity profiles produced by the various geometries produce distinguishable differences. Overall spectral differences between the geometries do not exceed 15 per cent in the most extreme cases. It is found that emissivity profiles can be useful in distinguishing point source and extended geometries given high quality spectral data of extreme, bright sources over long exposure times. In combination with reflection fraction, timing, and spectral analysis we may use emissivity profiles to discern the geometry of the X-ray source.Comment: 15 pages, 12 figures. Accepted for publication in MNRA