Showing 1321 - 1330 of 2105 Items

Two antisymmetric hypermultiplets in N = 2 SU(N) gauge theory: Seiberg-Witten curve and M-theory interpretation

Date: 1999-10-04

Creator: Isabel P. Ennes

Stephen G. Naculich

Henric Rhedin

Howard J. Schnitzer

Access: Open access

The one-instanton contribution to the prepotential for N = 2 supersymmetric gauge theories with classical groups exhibits a universality of form. We extrapolate the observed regularity to SU (N) gauge theory with two antisymmetric hypermultiplets and Nf ≤ 3 hypermultiplets in the defining representation. Using methods developed for the instanton expansion of non-hyperelliptic curves, we construct an effective quartic Seiberg-Witten curve that generates this one-instanton prepotential. We then interpret this curve in terms of an M-theoretic picture involving NS 5-branes, D4-branes, D6-branes, and orientifold sixplanes, and show that for consistency, an infinite chain of 5-branes and orientifold sixplanes is required, corresponding to a curve of infinite order. © 1999 Elsevier Science B.V. All rights reserved.


Comparing enhancer action in cis and in trans

Date: 2012-08-01

Creator: Jack R. Bateman

Justine E. Johnson

Melissa N. Locke

Access: Open access

Studies from diverse systems have shown that distinct interchromosomal interactions are a central component of nuclear organization. In some cases, these interactions allow an enhancer to act in trans, modulating the expression of a gene encoded on a separate chromosome held in close proximity. Despite recent advances in uncovering such phenomena, our understanding of how a regulatory element acts on another chromosome remains incomplete. Here, we describe a transgenic approach to better understand enhancer action in trans in Drosophila melanogaster. Using phiC31-based recombinase-mediated cassette exchange (RMCE), we placed transgenes carrying combinations of the simple enhancer GMR, a minimal promoter, and different fluorescent reporters at equivalent positions on homologous chromosomes so that they would pair via the endogenous somatic pairing machinery of Drosophila. Our data demonstrate that the enhancer GMR is capable of activating a promoter in trans and does so in a variegated pattern, suggesting stochastic interactions between the enhancer and the promoter when they are carried on separate chromosomes. Furthermore, we quantitatively assessed the impact of two concurrent promoter targets in cis and in trans to GMR, demonstrating that each promoter is capable of competing for the enhancer's activity, with the presence of one negatively affecting expression from the other. Finally, the single-cell resolution afforded by our approach allowed us to show that promoters in cis and in trans to GMR can both be activated in the same nucleus, implying that a single enhancer can share its activity between multiple promoter targets carried on separate chromosomes. © 2012 by the Genetics Society of America.


One-instanton predictions of Seiberg-Witten curves for product groups

Date: 1999-01-01

Creator: Isabel P. Ennes

Stephen G. Naculich

Henric Rhedin

Howard J. Schnitzer

Access: Open access

One-instanton predictions for the prepotential are obtained from the Seiberg-Witten curve for the Coulomb branch of script N sign = 2 supersymmetric gauge theory for the product group IIn=1m SU(Nn) with a massless matter hypermultiplet in the bifundamental representation (Nn,N̄n+1) of SU(Nn) × SU(Nn+1) for n = 1 to m - 1, together with N0 and Nm+1 matter hypermultiplets in the fundamental representations of SU(N1) and SU(Nm) respectively. The derivation uses a generalization of the systematic perturbation expansion about a hyperelliptic curve developed by us in earlier work. © 1999 Published by Elsevier Science B.V. All rights reserved.


The large-scale geometry of some metabelian groups

Date: 2003-01-01

Creator: Jennifer Taback

Kevin Whyte

Access: Open access



Superconformal coset equivalence from level-rank duality

Date: 1997-11-17

Creator: Stephen G. Naculich

Howard J. Schnitzer

Access: Open access

We construct a one-to-one map between the primary fields of the N = 2 superconformal Kazama-Suzuki models G(m, n, k) and G(k, n, m) based on complex Grassmannian cosets, using level-rank duality of Wess-Zumino-Witten models. We then show that conformal weights, superconformal U(1) charges, modular transformation matrices, and fusion rules are preserved under this map, providing strong evidence for the equivalence of these coset models. © 1997 Elsevier Science B.V.


Effects of stochasticity on the length and behaviour of ecological transients

Date: 2021-07-01

Creator: Alan Hastings

Karen C. Abbott

Kim Cuddington

Tessa B. Francis

Ying Cheng, Lai

Andrew Morozov

Access: Open access

There is a growing recognition that ecological systems can spend extended periods of time far away from an asymptotic state, and that ecological understanding will therefore require a deeper appreciation for how long ecological transients arise. Recent work has defined classes of deterministic mechanisms that can lead to long transients. Given the ubiquity of stochasticity in ecological systems, a similar systematic treatment of transients that includes the influence of stochasticity is important. Stochasticity can of course promote the appearance of transient dynamics by preventing systems from settling permanently near their asymptotic state, but stochasticity also interacts with deterministic features to create qualitatively new dynamics. As such, stochasticity may shorten, extend or fundamentally change a system's transient dynamics. Here, we describe a general framework that is developing for understanding the range of possible outcomes when random processes impact the dynamics of ecological systems over realistic time scales. We emphasize that we can understand the ways in which stochasticity can either extend or reduce the lifetime of transients by studying the interactions between the stochastic and deterministic processes present, and we summarize both the current state of knowledge and avenues for future advances.


Adjusting to Global change through clonal growth and epigenetic variation

Date: 2016-07-26

Creator: Richard S. Dodd

Vladimir Douhovnikoff

Access: Open access

The earth is experiencing major changes in global and regional climates and changes are predicted to accelerate in the future. Many species will be under considerable pressure to evolve, to migrate, or be faced with extinction. Clonal plants would appear to be at a particular disadvantage due to their limited mobility and limited capacity for adaptation. However, they have outlived previous environmental shifts and clonal species have persisted for millenia. Clonal spread offers unique ecological advantages, such as resource sharing, risk sharing, and economies of scale among ramets within genotypes. We suggest that ecological attributes of clonal plants, in tandem with variation in gene regulation through epigenetic mechanisms that facilitate and optimize phenotype variation in response to environmental change may permit them to be well suited to projected conditions.


Exclusive hadronic B decays to charm and charmonium final states

Date: 1994-01-01

Creator: M. S. Alam

I. J. Kim

B. Nemati

J. J. ONeill

H., Severini

C. R. Sun

M. M. Zoeller

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

F. Butler

X. Fu

G. Kalbfleisch

W. R. Ross

P. Skubic

J. Snow

P. L. Wang

M. Wood

D. N. Brown

J. Fast

Access: Open access

We have fully reconstructed decays of both B»0 and B- mesons into final states containing either D, D*, D**, , or c1 mesons. This allows us to obtain new results on many physics topics including branching ratios, tests of the factorization hypothesis, color suppression, resonant substructure, and the B - B»0 mass difference. © 1994 The American Physical Society.


Corrigendum to "controls on the movement and composition of firn air at the West Antarctic ice sheet divide"

Date: 2014-09-16

Creator: M. O. Battle

J. P. Severinghaus

E. D. Sofen

D. Plotkin

A. J., Orsi

M. Aydin

S. A. Montzka

T. Sowers

P. P. Tans

Access: Open access



Erratum: Measurement of the Tau lepton electronic branching fraction (Physical Review Letters (1993) 71, 20, (3395-3396))

Date: 1993-12-01

Creator: D. S. Akerib

B. Barish

M. Chadha

D. F. Cowen

G., Eigen

J. S. Miller

J. Urheim

A. J. Weinstein

D. Acosta

G. Masek

B. Ong

H. Paar

M. Sivertz

A. Bean

J. Gronberg

R. Kutschke

S. Menary

R. J. Morrison

H. N. Nelson

J. D. Richman

H. Tajima

D. Schmidt

D. Sperka

M. S. Witherell

M. Procario

S. Yang

M. Daoudi

W. T. Ford

D. R. Johnson

K. Lingel

M. Lohner

Access: Open access