Showing 91 - 100 of 733 Items
Sign changes of Fourier coefficients of Hilbert modular forms
Date: 2014-01-01
Creator: Jaban Meher, Naomi Tanabe
Access: Open access
- Sign changes of Fourier coefficients of various modular forms have been studied. In this paper, we analyze some sign change properties of Fourier coefficients of Hilbert modular forms, under the assumption that all the coefficients are real. The quantitative results on the number of sign changes in short intervals are also discussed. © 2014 Elsevier Inc.
Simple-current symmetries, rank-level duality, and linear skein relations for Chern-Simons graphs
Date: 1993-04-12
Creator: Stephen G. Naculich, Harold A. Riggs, Howard J. Schnitzer
Access: Open access
- A previously proposed two-step algorithm for calculating the expectation values of arbitrary Chern-Simons graphs fails to determine certain crucial signs. The step which involves calculating tetrahedra by solving certain non-linear equations is repaired by introducing additional linear equations. The step which involves reducing arbitrary graphs to sums of products of tetrahedra remains seriously disabled, apart from a few exceptional cases. As a first step towards a new algorithm for general graphs we find useful linear equations for those special graphs which support knots and links. Using the improved set of equations for tetrahedra we examine the symmetries between tetrahedra generated by arbitrary simple currents. Along the way we describe the simple, classical origin of simple-current charges. The improved skein relations also lead to exact identities between planar tetrahedra in level K G(N) and level N G(K) Chern-Simons theories, where G(N) denotes a classical group. These results are recast as WZW braid-matrix identities and as identities between quantum 6-jsymbols at appropriate roots of unity. We also obtain the transformation properties of arbitrary graphs, knots, and links under simple-current symmetries and rank-level duality. For links with knotted components this requires precise control of the braid eigenvalue permutation signs, which we obtain from plethysm and an explicit expression for the (multiplicity-free) signs, valid for all compact gauge groups and all fusion products. © 1993.
Combinatorial and metric properties of Thompson's group t
Date: 2009-02-01
Creator: José Burillo, Sean Cleary, Melanie Stein, Jennifer Taback
Access: Open access
- We discuss metric and combinatorial properties of Thompson's group T, including normal forms for elements and unique tree pair diagram representatives. We relate these properties to those of Thompson's group F when possible, and highlight combinatorial differences between the two groups. We define a set of unique normal forms for elements of T arising from minimal factorizations of elements into natural pieces. We show that the number of carets in a reduced representative of an element of T estimates the word length, that F is undistorted in T, and we describe how to recognize torsion elements in T. © 2008 American Mathematical Society Reverts to public domain 28 years from publication.
Atmospheric potential oxygen: New observations and their implications for some atmospheric and oceanic models
Date: 2006-03-01
Creator: Mark Battle, Sara Mikaloff Fletcher, Michael L. Bender, Ralph F. Keeling, Andrew C., Manning, Nicolas Gruber, Pieter P. Tans, Melissa B. Hendricks, David T. Ho, Caroline Simonds, Robert Mika, Bill Paplawsky
Access: Open access
- Measurements of atmospheric O2/N2 ratios and CO2 concentrations can be combined into a tracer known as atmospheric potential oxygen (APO ≈ O2/N2 + CO2) that is conservative with respect to terrestrial biological activity. Consequently, APO reflects primarily ocean biogeochemistry and atmospheric circulation. Building on the work of Stephens et al. (1998), we present a set of APO observations for the years 1996-2003 with unprecedented spatial coverage. Combining data from the Princeton and Scripps air sampling programs, the data set includes new observations collected from ships in the low-latitude Pacific. The data show a smaller interhemispheric APO gradient than was observed in past studies, and different structure within the hemispheres. These differences appear to be due primarily to real changes in the APO field over time. The data also show a significant maximum in APO near the equator. Following the approach of Gruber et al. (2001), we compare these observations with predictions of APO generated from ocean O2 and CO2 flux fields and forward models of atmospheric transport. Our model predictions differ from those of earlier modeling studies, reflecting primarily the choice of atmospheric transport model (TM3 in this study). The model predictions show generally good agreement with the observations, matching the size of the interhemispheric gradient, the approximate amplitude and extent of the equatorial maximum, and the amplitude and phasing of the seasonal APO cycle at most stations. Room for improvement remains. The agreement in the interhemispheric gradient appears to be coincidental; over the last decade, the true APO gradient has evolved to a value that is consistent with our time-independent model. In addition, the equatorial maximum is somewhat more pronounced in the data than the model. This may be due to overly vigorous model transport, or insufficient spatial resolution in the air-sea fluxes used in our modeling effort. Finally, the seasonal cycles predicted by the model of atmospheric transport show evidence of an excessive seasonal rectifier in the Aleutian Islands and smaller problems elsewhere. Copyright 2006 by the American Geophysical Union.
Observation of the charmed baryon c+ and measurement of the isospin mass splittings of the c
Date: 1993-01-01
Creator: G. Crawford, C. M. Daubenmier, R. Fulton, D. Fujino, K. K., Gan, K. Honscheid, H. Kagan, R. Kass, J. Lee, R. Malchow, F. Morrow, Y. Skovpen, M. Sung, C. White, J. Whitmore, P. Wilson, F. Butler, X. Fu, G. Kalbfleisch, M. Lambrecht, W. R. Ross, P. Skubic, J. Snow, P. L. Wang, M. Wood, D. Bortoletto, D. N. Brown, J. Fast, R. L. McIlwain, T. Miao, D. H. Miller
Access: Open access
- We observe the c+ baryon decaying to Λc+π0 and measure the mass difference M(c+)-M(Λc+) to be 168.5±0.2 MeV/c2. We also measure the mass differences M(c++)-M(Λc+) and M(c0-M(Λc+) with improved precision and determine the isospin mass splittings M(c++)-M(c0) and M(c+)-M(c0) to be 1.1±0.4±0.1 MeV/c2 and 1.4±0.5±0.3 MeV/c2, respectively. Our results indicate that the light quark mass difference does not dominate the isospin mass splitting in c. © 1993 The American Physical Society.
Inclusive (2P) production in (3S) decay
Date: 1991-01-01
Creator: R. Morrison, D. Schmidt, M. Procario, D. R. Johnson, K., Lingel, P. Rankin, J. G. Smith, J. Alexander, M. Artuso, C. Bebek, K. Berkelman, D. Besson, T. E. Browder, D. G. Cassel, E. Cheu, D. M. Coffman, P. S. Drell, R. Ehrlich, R. S. Galik, M. Garcia-Sciveres, B. Geiser, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, K. Honscheid, J. Kandaswamy, N. Katayama, D. L. Kreinick, J. D. Lewis, G. S. Ludwig
Access: Open access
- Using the CsI calorimeter of the CLEO II detector, the spin triplet b(2P) states are observed in (3S) radiative decays with much higher statistics than seen in previous experiments. The observed mass splittings are not described well by theoretical models, while the relative branching ratios agree with predictions that include relativistic corrections to the radiative transition rates. © 1991 The American Physical Society.
Trumpet slices in Kerr spacetimes
Date: 2014-12-29
Creator: Kenneth A. Dennison, Thomas W. Baumgarte, Pedro J. Montero
Access: Open access
- We introduce a new time-independent family of analytical coordinate systems for the Kerr spacetime representing rotating black holes. We also propose a (2+1)+1 formalism for the characterization of trumpet geometries. Applying this formalism to our new family of coordinate systems we identify, for the first time, analytical and stationary trumpet slices for general rotating black holes, even for charged black holes in the presence of a cosmological constant. We present results for metric functions in this slicing and analyze the geometry of the rotating trumpet surface.
Electronic branching ratio of the lepton
Date: 1992-01-01
Creator: R. Ammar, P. Baringer, D. Coppage, R. Davis, M., Kelly, N. Kwak, H. Lam, S. Ro, Y. Kubota, M. Lattery, J. K. Nelson, D. Perticone, R. Poling, S. Schrenk, R. Wang, M. S. Alam, I. J. Kim, B. Nemati, V. Romero, C. R. Sun, P. N. Wang, M. M. Zoeller, G. Crawford, R. Fulton, K. K. Gan, H. Kagan, R. Kass, J. Lee, R. Malchow, F. Morrow, M. K. Sung
Access: Open access
- Using data accumulated by the CLEO I detector operating at the Cornell Electron Storage Ring, we have measured the ratio R=( e» e ) 1 where " 1 is the decay rate to final states with one charged particle. We find R=0.2231 0.0044 0.0073 where the first error is statistical and the second is systematic. Together with the measured topological one-charged-particle branching fraction, this yields the branching fraction of the lepton to electrons, Be=0.192 0.004 0.006. © 1992 The American Physical Society.
Bilad al-brazil: The importance of west african scholars in brazilian islamic education and practice in historic and contemporary perspective
Date: 2021-02-01
Creator: Ayodeji Ogunnaike
Access: Open access
- While it is well established now that the middle passage did not entirely separate Africans who were forcibly brought to the Americas from their home cultures and traditions, these connections are often studied and understood in the form of survivals or ancestral memory. This paper argues that in major urban centers in Brazil until around the time of World War I, West Africans not only managed to recreate Islamic communities and intellectual traditions, but maintained important contacts with their homelands. In much the same way that scholars have argued that the Sahara constituted an avenue of exchange and connection between North Africa and Bilad al-Sudan, I argue here that the Atlantic Ocean was not an insurmountable barrier but provided opportunities for African Muslims to extend the traditions of Bilad al-Sudan into Brazil—albeit to a much lesser extent.
Monteverde: ecología y conservación de un bosque nuboso tropical
Date: 2014-12-01
Creator: Nathaniel T Wheelwright, Nalini M Nadkarni
Access: Open access
- La Reserva Biológica Bosque Nuboso Monteverde ha capturado la atención mundial de biólogos, conservacionistas y ecólogos y allí se han hecho vastas investigaciones durante los últimos 40 años. Unos 40.000 ecoturistas visitan el Bosque Nuboso cada año y se considera el bosque lluvioso arquetípico de las altitudes altas. Este libro, una traducción actualizada de "Monteverde: Ecology and Conservation of a Tropical Cloud Forest", editado por Nalini Nadkarni y Nathaniel T. Wheelwright (Oxford University Press, 2000) presenta capítulos sintéticos y recuentos específicos escritos por más de 100 biólogos y residentes locales. En un solo volumen documenta todo lo que se sabe en 2014 de la diversidad biológica de Monteverde, Costa Rica, y cómo protegerla. The Monteverde Cloud Forest Reserve has captured the worldwide attention of biologists, conservationists, and ecologists and has been the setting for extensive investigation over the past 40 years. Roughly 40,000 ecotourists visit the Cloud Forest each year, and it is often considered the archetypal high-altitude rain forest. This book, an updated and expanded version of "Monteverde: Ecology and Conservation of a Tropical Cloud Forest", edited by Nalini Nadkarni and Nathaniel T. Wheelwright (Oxford University Press, 2000), features synthetic chapters and specific accounts written by more than 100 biologists and local residents. The 862-page book includes 12 new short chapters and documents in a single volume everything known in 2014 about the biological diversity of Monteverde, Costa Rica, and how to protect it.