Elliptic operators on manifolds with singularities and K-homology

It is well known that elliptic operators on a smooth compact manifold are classified by K-homology. We prove that a similar classification is also valid for manifolds with simplest singularities: isolated conical points and fibered boundary. The main ingredients of the proof of these results are: an analog of the Atiyah-Singer difference construction in the noncommutative case and an analog of Poincare isomorphism in K-theory for our singular manifolds. As applications we give a formula in topological terms for the obstruction to Fredholm problems on manifolds with singularities and a formula for K-groups of algebras of pseudodifferential operators.Comment: revised version; 25 pages; section with applications expande

Circular Polarization Induced by Scintillation in a Magnetized Medium

A new theory is presented for the development of circular polarization as radio waves propagate through the turbulent, birefringent interstellar medium. The fourth order moments of the wavefield are calculated and it is shown that unpolarized incident radiation develops a nonzero variance in circular polarization. A magnetized turbulent medium causes the Stokes parameters to scintillate in a non-identical manner. A specific model for this effect is developed for the case of density fluctuations in a uniform magnetic field.Comment: 16 pages, 1 figure, Phys. Rev. E, accepte

A local families index formula for d-bar operators on punctured Riemann surfaces

Using heat kernel methods developed by Vaillant, a local index formula is obtained for families of d-bar operators on the Teichmuller universal curve of Riemann surfaces of genus g with n punctures. The formula also holds on the moduli space M{g,n} in the sense of orbifolds where it can be written in terms of Mumford-Morita-Miller classes. The degree two part of the formula gives the curvature of the corresponding determinant line bundle equipped with the Quillen connection, a result originally obtained by Takhtajan and Zograf.Comment: 47 page

A generalized photon propagator

A covariant gauge independent derivation of the generalized dispersion relation of electromagnetic waves in a medium with local and linear constitutive law is presented. A generalized photon propagator is derived. For Maxwell constitutive tensor, the standard light cone structure and the standard Feynman propagator are reinstated

Time-Distance Seismology of the Solar Corona with CoMP

We employ a sequence of Doppler images obtained with the Coronal Multi-channel Polarimeter (CoMP) instrument to perform time-distance seismology of the solar corona. We construct the first k-omega diagrams of the region. These allow us to separate outward and inward propagating waves and estimate the spatial variation of the plane-of-sky projected phase speed, and the relative amount of outward and inward directed wave power. The disparity between outward and inward wave power and the slope of the observed power law spectrum indicate that low-frequency Alfvenic motions suffer significant attenuation as they propagate, consistent with isotropic MHD turbulence.Comment: In Press ApJ. 8 pages and 8 color figure

Magnetic Photon Splitting: the S-Matrix Formulation in the Landau Representation

Calculations of reaction rates for the third-order QED process of photon splitting in strong magnetic fields traditionally have employed either the effective Lagrangian method or variants of Schwinger's proper-time technique. Recently, Mentzel, Berg and Wunner (1994) presented an alternative derivation via an S-matrix formulation in the Landau representation. Advantages of such a formulation include the ability to compute rates near pair resonances above pair threshold. This paper presents new developments of the Landau representation formalism as applied to photon splitting, providing significant advances beyond the work of Mentzel et al. by summing over the spin quantum numbers of the electron propagators, and analytically integrating over the component of momentum of the intermediate states that is parallel to field. The ensuing tractable expressions for the scattering amplitudes are satisfyingly compact, and of an appearance familiar to S-matrix theory applications. Such developments can facilitate numerical computations of splitting considerably both below and above pair threshold. Specializations to two regimes of interest are obtained, namely the limit of highly supercritical fields and the domain where photon energies are far inferior to that for the threshold of single-photon pair creation. In particular, for the first time the low-frequency amplitudes are simply expressed in terms of the Gamma function, its integral and its derivatives. In addition, the equivalence of the asymptotic forms in these two domains to extant results from effective Lagrangian/proper-time formulations is demonstrated.Comment: 19 pages, 3 figures, REVTeX; accepted for publication in Phys. Rev.

Insights on Māori Social Enterprise 2017- Pakihi What Kaupapa

Te Puni Kōkiri would like to thank Maui Lab at the University of Canterbury and acknowledge with much appreciation the intelligence provided by the Research report: Māori Social Enterprise – A preliminary scoping and needs analysis (unpublished). In particular, a mihi to the lead author Sacha McMeeking, supported by William Grant and Unaiki Melrose. We also wish to thank Ākina, Maori Womens Development Inc. and Dovetail for their contribution to Te Hiringa Hononga Community Social Enterprise Programme and the findings from the Programme that have contributed to this resource. And finally, we wish to particularly acknowledge all the Māori social entrepreneurs who contributed their journeys and insights for the resource. We also wish to acknowledge Te Pūtahitanga o Te Waipounamu who allowed Maui Lab to draw upon insights into Māori social enterprise gained while working with the kaupapa they have supported.This resource has been prepared by Te Puni Kōkiri to provide insight and share initial findings from Te Puni Kōkiri commissioned research and evaluation of Māori social enterprise in Aotearoa. These insights are intended to contribute to a wider discussion around the kinds of supports the Government should focus on and invest in to grow Māori social enterprise, as part of its commitment to He kai kei aku ringa – the Crown-Māori Economic Growth Partnership. The insights in this report are primarily sourced from: › Māori Social Enterprise – A preliminary scoping and needs analysis completed for Te Puni Kōkiri by Maui Lab at the University of Canterbury (unpublished). The lead author is Sacha McMeeking, supported by William Grant and Unaiki Melrose. This report was commissioned to better understand what Māori social enterprise is in Aotearoa and inform key stakeholders about designing programmes and policy settings that could support Māori social enterprise development. › Te Hiringa Hononga Community Social Enterprise Programme: 2017 Evaluation Report (unpublished). Prepared by Dr Adrian Field, Debbie Goodwin and Louise Were. Te Hiringa Hinonga Community Social Enterprise Programme was an investment pilot initiative to build the capability of Māori social enterprises in Te Tairāwhiti and Te Taitokerau in 2016/17. The pilot was trialled in both regions, of which have high Māori populations to support the growth of Māori social enterprise capability

PROBE: preparedness and response - online bioterrorism education: foundation knowledge training

Terrorism and the resulting geo-political state of affairs have created a need for health professionals to be well prepared for bioterror. In our socio-political climate we need a rational approach to managing public perceptions and need to be able to lead an appropriate response to suspected bioterror events. This website was created as a resource for public health professionals interested in learning how to be more effective at preparing for and responding to a terrorist attack using bioweapons. Who is involved: The Anton Breinl Centre for Public Health and Tropical Medicine (ABC) at James Cook University, has particular expertise in disaster/emergency management, biological agents that constitute the greatest threat, and the sociology of terror. The ABC was the first institution in Australia to develop a bioterrorism course. What is PROBE? The PROBE (Preparedness & Response - Online Bioterrorism Education) project designs and develops multimedia-based, interactive decision support simulation modules for training and support of health professionals in the management of bioterrorism events in an Australian context. PROBE modules provide knowledge and experience that to enhance ability to make timely and appropriate decisions to management of bioterrorism events. In the foundation chapters, students develop an awareness of the increased focus and attention on bioterrorism research and preparedness and explore the implications for the public health sector

Counting Majorana zero modes in superconductors

A counting formula for computing the number of (Majorana) zero modes bound to topological point defects is evaluated in a gradient expansion for systems with charge-conjugation symmetry. This semi-classical counting of zero modes is applied to some examples that include graphene and a chiral p-wave superconductor in two-dimensional space. In all cases, we explicitly relate the counting of zero modes to Chern numbers.Comment: 21 pages, 3 figure

Variability of USA East Coast surface total alkalinity distributions revealed by automated instrument measurements

Seawater total alkalinity (TA) is one important determinant used to monitor the ocean carbon cycle, whose spatial distributions have previously been characterized along the United States East Coast via discrete bottle samples. Using these data, several regional models for TA retrievals based on practical salinity (S) have been developed. Broad-scale seasonal or interannual variations, however, are not well resolved in these models and existing data are highly seasonally biased. This study reports findings from the first long duration deployment of a new, commercially available TA titrator aboard a research vessel and the continuous underway surface TA measurements produced. The instrument, operated on seven East Coast USA cruises during six months in 2017 and for two months in 2018 on the summertime East Coast Ocean Acidification survey (ECOA-2), collected a total of nearly 11,000 surface TA measurements. Data from these efforts, along with a newly synthesized set of more than 11,000 regional surface TA observations, are analyzed to re-examine distributions of TA and S along the United States East Coast. Overall, regional distributions of S and TA generally agreed with prior findings, but linear TA:S regressions varied markedly over time and deviated from previously developed models. This variability is likely due to a combination of biological, seasonal, and episodic influences and indicates that substantial errors of ±10–20 μmol kg−1 in TA estimation from S can be expected due to these factors. This finding has likely implications for numerical ecosystem modeling and inorganic carbon system calculations. New results presented in this paper provide refined surface TA:S relationships, present more data in space and time, and improve TA modeling uncertainty