758 research outputs found
Laminations and groups of homeomorphisms of the circle
If M is an atoroidal 3-manifold with a taut foliation, Thurston showed that
pi_1(M) acts on a circle. Here, we show that some other classes of essential
laminations also give rise to actions on circles. In particular, we show this
for tight essential laminations with solid torus guts. We also show that
pseudo-Anosov flows induce actions on circles. In all cases, these actions can
be made into faithful ones, so pi_1(M) is isomorphic to a subgroup of
Homeo(S^1). In addition, we show that the fundamental group of the Weeks
manifold has no faithful action on S^1. As a corollary, the Weeks manifold does
not admit a tight essential lamination, a pseudo-Anosov flow, or a taut
foliation. Finally, we give a proof of Thurston's universal circle theorem for
taut foliations based on a new, purely topological, proof of the Leaf Pocket
Theorem.Comment: 50 pages, 12 figures. Ver 2: minor improvement
Moving Towards a Culturally Diverse Accounting Profession
This paper discusses the increasing diversity in the accounting profession. Evidence is presented substantiating that over one third of recent accounting graduates are from ethnic minority backgrounds, the majority of whom are Asian/Pacific Islanders. In our university specific data, we find an even higher percentage (71%) of ethnic minorities receiving accounting degrees, with Asian/Pacific Islanders as the majority group. We also show that over one fourth of new accounting graduates hired by accounting firms are ethnic minorities of which fifty percent are Asian/Pacific Islanders
An ascending HNN extension of a free group inside SL(2,C)
We give an example of a subgroup of SL(2,C) which is a strictly ascending HNN
extension of a non-abelian finitely generated free group F. In particular, we
exhibit a free group F in SL(2,C) of rank 6 which is conjugate to a proper
subgroup of itself. This answers positively a question of Drutu and Sapir. The
main ingredient in our construction is a specific finite volume (noncompact)
hyperbolic 3-manifold M which is a surface bundle over the circle. In
particular, most of F comes from the fundamental group of a surface fiber. A
key feature of M is that there is an element of its fundamental group with an
eigenvalue which is the square root of a rational integer. We also use the
Bass-Serre tree of a field with a discrete valuation to show that the group F
we construct is actually free.Comment: 7 pages. V2: minor improvements in expositio
Automorphic forms and rational homology 3āspheres
We investigate a question of Cooper adjacent to the Virtual Haken Conjecture. Assuming certain conjectures in number theory, we show that there exist hyperbolic rational homology 3āspheres with arbitrarily large injectivity radius. These examples come from a tower of abelian covers of an explicit arithmetic 3āmanifold. The conjectures
we must assume are the Generalized Riemann Hypothesis and a mild strengthening of results of Taylor et al on part of the Langlands Program for GL2 of an imaginary quadratic field.
The proof of this theorem involves ruling out the existence of an irreducible two dimensional Galois representation rho of Gal(Qbar/Qsqrt-2) satisfying certain prescribed ramification conditions. In contrast to similar questions of this form, rho is allowed to have arbitrary ramification at some prime pi of Z[sqrt -2].
In the next paper in this volume, Boston and Ellenberg apply proāp techniques to our examples and show that our result is true unconditionally. Here, we give additional examples where their techniques apply, including some non-arithmetic examples.
Finally, we investigate the congruence covers of twist-knot orbifolds. Our experimental evidence suggests that these topologically similar orbifolds have rather different behavior depending on whether or not they are arithmetic. In particular, the congruence covers of the non-arithmetic orbifolds have a paucity of homology
Corporate Social Responsibility and Earnings Reporting
Despite increasing interests on corporate social responsibility (CSR) activities among managers, the relationship between CSR and firm value through earnings reporting quality is still unclear. Absence of a strong positive effect of CSR on firm value has led researchers to believe that CSR is a res ult of a principal-agent issue between shareholders and managers. This study argues CSR represents a corporate culture that influences how a corporation reports its earnings. CSR influ ences earnings reporting Ā·instead ofearnings reporting drives CSR to delude shareholders. CSR induces better earnings reporting quality, therefore, CSR has an indirect but positive effect on firm value
Pseudogap and the specific heat of high superconductors
The specific heat of a two dimensional repulsive Hubbard model with local
interaction is investigated. We use the two-pole approximation which exhibits
explicitly important correlations that are sources of the pseudogap anomaly.
The interplay between the specific heat and the pseudogap is the main focus of
the present work. Our self consistent numerical results show that above the
occupation , the specific heat starts to decrease due to the
presence of a pseudogap in the density of states. We have also observed a two
peak structure in the specific heat. Such structure is robust with respect to
the Coulomb interaction but it is significantly affected by the occupation
. A detailed study of the two peak structure is carried out in terms of
the renormalized quasi-particle bands. The role of the second nearest neighbor
hopping on the specific heat behavior and on the pseudogap, is extensively
discussed.Comment: 6 pages, 6 figures, accepted for publication in Solid State
Communication
Specific heat of a non-local attractive Hubbard model
The specific heat of an attractive (interaction ) non-local Hubbard
model is investigated. We use a two-pole approximation which leads to a set of
correlation functions. In particular, the correlation function $\
G\delta\delta=1-n_Tn_T=n_{\uparrow}+n_{\downarrow}(0,\pm\pi)(\pm\pi,0)$ eliminates the two peak structure, the low
temperature peak remaining. The effects of the second nearest neighbor hopping
on the specific heat are also investigated.Comment: 5 pages, 7 figure
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