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Spectral geometry, homogeneous spaces and differential forms with finite Fourier series
Dunn, C,Gilkey, P,Park, J H The Institute of Physics 2008 JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL Vol.41 No.13
<P>Let <I>G</I> be a compact Lie group acting transitively on Riemannian manifolds <I>M<SUB>i</SUB></I> and let π:<I>M</I><SUB>1</SUB> → <I>M</I><SUB>2</SUB> be a <I>G</I>-equivariant Riemannian submersion. We show that a smooth differential form &phis; on <I>M</I><SUB>2</SUB> has finite Fourier series on <I>M</I><SUB>2</SUB> if and only if the pull back π*&phis; has finite Fourier series on <I>M</I><SUB>1</SUB>.</P>
Instanton determinant with arbitrary quark mass: WKB phase-shift method and derivative expansion
Dunne, Gerald V.,Hur, Jin,Lee, Choonkyu,Min, Hyunsoo Elsevier 2004 Physics letters: B Vol.600 No.3
<P><B>Abstract</B></P><P>The fermion determinant in an instanton background for a quark field of arbitrary mass is studied using the Schwinger proper-time representation with WKB scattering phase shifts for the relevant partial-wave differential operators. Previously, results have been obtained only for the extreme small and large quark mass limits, not for intermediate interpolating mass values. We show that consistent renormalization and large-mass asymptotics requires up to third-order in the WKB approximation. This procedure leads to an almost analytic answer, requiring only modest numerical approximation, and yields excellent agreement with the well-known extreme small and large mass limits. We estimate that it differs from the exact answer by no more than 6% for generic mass values. In the philosophy of the derivative expansion the same amplitude is then studied using a Heisenberg–Euler-type effective action, and the leading order approximation gives a surprisingly accurate answer for all masses.</P>
Tariffs vs. Quotas over the Business Cycle
Dunn,, Robert M. Jr. 세종대학교 국제경제연구소 1991 Journal of Economic Integration Vol.6 No.1
This paper extends the literature on tariffs vs. quotas by comparing their impacts in a world of macroeconomic shocks and trade account imbalances with fixed exchange rates. The effects of tariffs and quotas on output, prices, import volumes, and profits are compared both when business cycles originate in the importing country and when they start in the exporting country. In the former case the maintenance of a tariff reduces the domestic effect of a business cycle by passing some of its effect through to exporters, while a quota contains the effects of such shocks within the importing economy. When business cycles originate in the exporting country, most of the earlier conclusions are reversed. Countries wishing to minimize the disruptive impacts of domestic business cycles should choose tariffs rather than quotas as the primary tool of commercial policy, while those worried primarily about the domestic effects of foreign macroeconomic shocks should rely on quotas rather than tariffs.
Precise Quark-Mass Dependence of the Instanton Determinant
Dunne, Gerald V.,Hur, Jin,Lee, Choonkyu,Min, Hyunsoo American Physical Society 2005 Physical review letters Vol.94 No.7
<P>The fermion determinant in an instanton background for a quark field of arbitrary mass is determined exactly using an efficient numerical method to evaluate the determinant of a partial-wave radial differential operator. The bare sum over partial waves is divergent but can be renormalized in the minimal subtraction scheme using the result of WKB analysis of the large partial-wave contribution. Previously, only a few leading terms in the extreme small and large mass limits were known for the corresponding effective action. Our approach works for any quark-mass and interpolates smoothly between the analytically known small and large mass expansions.</P>
Numerical Simulation of BOR scattering and radiation using a higher order FEM
Dunn, E.A.,Jin-Kyu Byun,Branch, E.D.,Jian-Ming Jin Institute of Electrical and Electronics Engineers 2006 IEEE transactions on antennas and propagation Vol.54 No.3
<P>Numerical simulations of body-of-revolution geometries for scattering and radiation problems are presented. The formulation consists of a finite element-boundary integral (FE-BI) method which is based on a finite element method that uses higher order nodal-based scalar basis functions for the azimuthal field component and higher order edge-based vector basis functions for the transverse field. This formulation, when combined with a symmetric FE-BI hybridization scheme, yields a final system of equations that is more accurate than earlier first-order formulations. Numerical examples are given to demonstrate the accuracy and capabilities of the higher order solution</P>
Ince-Dunn, G.,Okano, Hirotaka J.,Jensen, K.B.,Park, W.Y.,Zhong, R.,Ule, J.,Mele, A.,Fak, John J.,Yang, C.,Zhang, C.,Yoo, J.,Herre, M.,Okano, H.,Noebels, Jeffrey L.,Darnell, Robert B. Cell Press 2012 Neuron Vol.75 No.6
The paraneoplastic neurologic disorders target several families of neuron-specific RNA binding proteins (RNABPs), revealing that there are unique aspects of gene expression regulation in the mammalian brain. Here, we used HITS-CLIP to determine robust binding sites targeted by the neuronal Elav-like (nElavl) RNABPs. Surprisingly, nElav protein binds preferentially to GU-rich sequences in vivo and in vitro, with secondary binding to AU-rich sequences. nElavl null mice were used to validate the consequence of these binding events in the brain, demonstrating that they bind intronic sequences in a position dependent manner to regulate alternative splicing and to 3'UTR sequences to regulate mRNA levels. These controls converge on the glutamate synthesis pathway in neurons; nElavl proteins are required to maintain neurotransmitter glutamate levels, and the lack of nElavl leads to spontaneous epileptic seizure activity. The genome-wide analysis of nElavl targets reveals that one function of neuron-specific RNABPs is to control excitation-inhibition balance in the brain. Video Abstract:
Conor Dunn,Michael Faloon,Edward Milman,Sina Pourtaheri,Kumar Sinah,Ki Hwang,Arash Emami 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.2
Study Design: Retrospective case series with prospective arm. Purpose: To assess the safety and accuracy of percutaneous lumbosacral pedicle screw placement (PLPSP) in the lumbosacral spine using intraoperative dual-planar fluoroscopy (DPF). Overview of Literature: There are several techniques available for achieving consistent, safe, and accurate results with PLPSP. There is a paucity of literature describing the beneficial operative, economic, and clinical outcomes of DPF, the most readily accessible image guidance system. Methods: From 2004 to 2014, 451 consecutive patients underwent PLPSP using DPF, for a total of 2,345 screw placement. The results of prospectively obtained postoperative computed tomography (CT) examinations of an additional 41 consecutive patients were compared with the results of 104 CT examinations obtained postoperatively due to clinical symptomatology; these results were interpreted by three reviewers. The rates of revision indicated by misplaced screws with consistent clinical symptomatology were compared between groups. Pedicle screw placement was graded according to 2-mm increments in medial pedicle wall breach and measurement of screw axis placement. Results: Seven of the 2,345 pedicle screws placed percutaneously with the use of the dual-planar fluoroscopic technique required revision because of a symptomatic misplaced screw, for a screw revision rate of 0.3%. There were no statistically significant demographic differences between patients who had screws revised and those who did not. All screws registered greater than 10 mA on electromyographic stimulation. In the 41 prospectively obtained CT examinations, one out of 141 screws (0.7%) was revised due to pedicle wall breach; whereas among the 104 patients with 352 screws, three screws were revised (0.9%). Conclusions: DPF is an extremely accurate, safe, and reproducible technique for placement of percutaneous pedicle screws and is a readily available and cost-effective alternative to CT-guided pedicle screw placement techniques. Postoperative CT evaluation is not necessary with PLPSP unless the patient is symptomatic. Acceptable electromyographic thresholds may need to be reevaluated.