Showing 691 - 700 of 733 Items
Date: 2015-11-01
Creator: Jennifer Taback, Sharif Younes
Access: Open access
- The definition of graph automatic groups by Kharlampovich, Khoussainov and Miasnikov and its extension to C-graph automatic by Elder and the first author raise the question of whether Thompson's group F is graph automatic. We define a language of normal forms based on the combinatorial "caret types", which arise when elements of F are considered as pairs of finite rooted binary trees. The language is accepted by a finite state machine with two counters, and forms the basis of a 3-counter graph automatic structure for the group.
Date: 2015-01-01
Creator: Charles E. Umbanhowar, Philip Camill, Mark B. Edlund, Christoph Geiss, Patrick, Henneghan, Kendra Passow
Access: Open access
- To better understand aquatic-terrestrial linkages in the sub-Arctic, and specifically the relative importance of landscape position versus land cover, we surveyed lakes, soils, land cover, and lake/basin characteristics in a 14000 km region of acidic forest-tundra landscape near northern Manitoba, Canada (59.56°N, 97.72°W) in 2009. We analyzed 39 different biological, chemical, and physical variables for lakes and soils. We used a remote-sensing-based classification to determine that the landscape was 21% water, 46% peat-forming lowland, and 24.9% open tundra, and we assigned lake order to all lakes based on the order of the outlet stream for each lake. Lakes were oligotrophic to mesotrophic (median total phosphorus: TP = 11.8 μg L ), N-limited (median dissolved inorganic nitrogen: TP = 1.6), acidic (median pH 5.7), and had moderate amounts of dissolved organic carbon (median DOC = 5.2 mg L ). We identified 2 principle groups of variables represented by DOC and conductivity/ cations, respectively, that captured major axes of lake variation. DOC, 2 measures of DOC quality (a /a [a proxy for molecular weight and aromaticity] and specific ultraviolet absorbance), and Fe and were significantly correlated with percent cover of lowland forest, but conductivity/cations were not correlated with variation in land cover. Soils were generally acidic (pH 2.7-4.4) and nutrient-poor, and wetland soils contained more carbon and higher concentrations of calcium, magnesium, and other cations than upland open tundra. Landscape position of lakes (measured as lake order) did not capture systematic differences in land cover or lake biogeochemistry. Our results highlight the importance of lowland export of DOC to lakes and further suggest the need for additional regional studies of aquatic-terrestrial connections in Arctic and sub-Arctic landscapes. 2 -1 -1 250 365
Date: 2006-07-01
Creator: Samuel P. Putnam, Maria A. Gartstein, Mary K. Rothbart
Access: Open access
- This article describes the development, reliability, and factor structure of a finely differentiated (18 dimensions) parent-report measure of temperament in 1.5- to 3-year-old children, using a cross-sectional sample (N = 317) and a longitudinal sample of primary (N = 104) and secondary (N = 61) caregivers. Adequate internal consistency was demonstrated for all scales and moderate inter-rater reliability was evident for most scales. Longitudinal stability correlations were primarily large over 6- and 12-month spans and moderate to large from 18 to 36 months. Factor analysis revealed a three-factor structure of Surgency/Extraversion, Negative Affectivity, and Effortful Control. In both samples and for both primary and secondary caregivers, older children received higher scores for Attention Focusing, Discomfort, Inhibitory Control, and Positive Anticipation. Primary caregivers rated females higher in Fear, and lower in High-intensity Pleasure, than males; secondary caregivers rated females higher than males in several aspects of Effortful Control. © 2006 Elsevier Inc. All rights reserved.
Date: 2016-12-01
Creator: Erika Franklin Fowler, Travis N. Ridout, Michael M. Franz
Access: Open access
- The 2016 presidential campaign broke the mold when it comes to patterns of political advertising. Using data from the Wesleyan Media Project, we show the race featured far less advertising than the previous cycle, a huge imbalance in the number of ads across candidates and one candidate who almost ignored discussions of policy. This departure from past patterns, however, was not replicated at the congressional level. We draw some lessons about advertising from the 2016 campaign, suggesting that its seeming lack of effectiveness may owe to the unusual nature of the presidential campaign with one unconventional candidate and the other using an unconventional message strategy, among other non-advertising related factors.
Date: 2016-11-01
Creator: Aba Mbirika, Thomas Pietraho, William Silver
Access: Open access
- We present a formula for the values of the sign representations of a complex reflection group G(r, p, n) in terms of its image under a generalized Robinson–Schensted algorithm.
Date: 1998-12-21
Creator: Isabel P. Ennes, Stephen G. Naculich, Henric Rhedin, Howard J. Schnitzer
Access: Open access
- One-instanton predictions are obtained from certain non-hyperelliptic Seiberg-Witten curves derived from M-theory for N = 2 supersymmetric gauge theories. We consider SU(N1) × SU(N2) gauge theory with a hypermultiplet in the bifundamental representation together with hypermultiplets in the defining representations of SU(N1) and SU(N2). We also consider SU(N) gauge theory with a hypermultiplet in the symmetric or antisymmetric representation, together with hypermultiplets in the defining representation. The systematic perturbation expansion about a hyperelliptic curve together with the judicious use of an involution map for the curve of the product groups provide the principal tools of the calculations. © 1999 Elsevier Science B.V.
Date: 1995-01-01
Creator: B. Barish, M. Chadha, S. Chan, D. F. Cowen, G., Eigen, J. S. Miller, C. O'Grady, J. Urheim, A. J. Weinstein, D. Acosta, M. Athanas, G. Masek, H. P. Paar, J. Gronberg, R. Kutschke, S. Menary, R. J. Morrison, S. Nakanishi, H. N. Nelson, T. K. Nelson, C. Qiao, J. D. Richman, A. Ryd, H. Tajima, D. Sperka, M. S. Witherell, M. Procario, R. Balest, K. Cho, M. Daoudi, W. T. Ford
Access: Open access
- We study the exclusive semileptonic B meson decays B-→D*0l-ν̄ and B̄0→D*+l-ν̄ using data collected with the CLEO II detector at the Cornell Electron-positron Storage Ring (CESR). We present measurements of the branching fractions scrB(B̄0→D*+l-ν̄)= (0.5/f00)[4.49±0.32(stat.)±0.39 (syst.)]% and scrB(B-→D*0l-(ν̄)= (0.5/f+-)[5.13±0.54 (stat) ±0.64 (syst)]%, where f00 and f+- are the neutral and charged B meson production fractions at the Υ(4S) resonance, respectively. Assuming isospin invariance and taking the ratio of charged to neutral B meson lifetimes measured at higher energy machines, we determine the ratio f+-/f00=1.04±0.13 (stat) ±0.12 (syst) ±0.10 (lifetime); further assuming f+-+f00=1 we also determine the partial width Γ(B̄→D*lν̄)=[29.9±1.9 (stat) ±2.7 (syst.) ±2.0 (lifetime)] ns-1 (independent of f+-/f00). From this partial width we calculate B̄→D*lν̄ branching fractions that do not depend on f+-/f00 or the individual B lifetimes, but only on the charged to neutral B lifetime ratio. The product of the CKM matrix element -Vcb- times the normalization of the decay form factor at the point of no recoil of the D* meson, scrF(y=1), is determined from a linear fit to the combined differential decay rate of the exclusive B̄→D*lν̄ decays: -Vcb-scrF(1)=0.0351±0.0019 (stat) ±0.0018 (syst) ±0.0008 (lifetime). The value for -Vcb- is extracted using theoretical calculations of the form factor normalization. © 1995 The American Physical Society.
Date: 1994-01-01
Creator: M. Battle, J. Ernst, Y. Kwon, S. Roberts, E. H., Thorndike, C. H. Wang, J. Dominick, M. Lambrecht, S. Sanghera, V. Shelkov, T. Skwarnicki, R. Stroynowski, I. Volobouev, G. Wei, P. Zadorozhny, M. Artuso, M. Goldberg, D. He, N. Horwitz, R. Kennett, R. Mountain, G. C. Moneti, F. Muheim, Y. Muheim, S. Playfer, Y. Rozen, S. Stone, M. Thulasidas, G. Vasseur, G. Zhu, J. Bartelt
Access: Open access
- Branching ratios for the dominant Cabibbo-suppressed decays of the τ lepton have been measured by CLEO II in e+e- annihilation at the Cornell Electron Storage Ring (s∼10.6 GeV) using kaons with momenta below 0.7 GeV/c. The inclusive branching ratio into one charged kaon is (1.60 ± 0.12 ± 0.19)%. For the exclusive decays, B(τ-→K-ντ)=(0.66±0.07±0.09)%, B(τ-→K-π0ντ)=(0.51±0.10±0.07)%, and, based on three events, B(τ-→K-2π0ντ)<0.3% at the 90% confidence level. These represent significant improvements over previous results. B(τ-→K-π0ντ) is measured for the first time with exclusive π0 reconstruction. © 1994 The American Physical Society.
Date: 1993-01-01
Creator: J. Bartelt, S. E. Csorna, Z. Egyed, V. Jain, D. S., Akerib, B. Barish, M. Chadha, S. Chan, D. F. Cowen, G. Eigen, J. S. Miller, C. O'Grady, J. Urheim, A. J. Weinstein, D. Acosta, M. Athanas, G. Masek, H. Paar, M. Sivertz, A. Bean, J. Gronberg, R. Kutschke, S. Menary, R. J. Morrison, S. Nakanishi, H. N. Nelson, T. K. Nelson, J. D. Richman, A. Ryd, H. Tajima, D. Schmidt
Access: Open access
- Using the CLEO II detector and a sample of 955 000 Υ(4S) decays we have confirmed charmless semileptonic decays of B mesons. In the momentum interval 2.3-2.6 GeV/c we observe an excess of 107±15±11 leptons, which we attribute to b→ulν. This result yields a model-dependent range of values for Vub/Vcb that is lower than has been obtained in previous studies. For the inclusive spectator model of Altarelli et al. we find Vub/Vcb=0.076±0.008. Models that describe b→ulν with a limited set of exclusive final states give Vub/Vcb=0.06-0.10. © 1993 The American Physical Society.
Date: 1991-01-01
Creator: Y. Kubota, J. K. Nelson, D. Perticone, R. Poling, S., Schrenk, G. Crawford, R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore, P. Wilson, D. Bortoletto, D. Brown, J. Dominick, R. L. McIlwain, D. H. Miller, M. Modesitt, C. R. Ng, S. F. Schaffner, E. I. Shibata, I. P.J. Shipsey, M. Battle, H. Kroha, K. Sparks, E. H. Thorndike, C. H. Wang, M. S. Alam
Access: Open access
- The spin alignment of D*+ mesons produced in e+e- annihilation at s=10.5 GeV is obtained from a study of the angular distribution of the decay D*+D0+. The alignment is studied as a function of momentum and compared to theoretical predictions. We find an average value of the spin alignment parameter of =0.040.020.01. We obtain a model-dependent measurement of the probability of producing a vector particle PV=0.770.020.01 for D mesons. © 1991 The American Physical Society.