A Question of Values: Community Engagement, Altruism, and Liberal Education

The Matriculation Convocation is the traditional start of the academic year. This is President Beck\u27s second Matriculation Convocation address

The Value of Individualized Instruction in Liberal Education

The Matriculation Convocation is the traditional start of the academic year. This is President Beck\u27s first Matriculation Convocation address

Liberal Philosophy, Free Discussion, and Individualized Learning at Lawrence

The Matriculation Convocation is the traditional start of the academic year. This is President Beck\u27s third Matriculation Convocation address

Perceiving Oppression: Relationships with Resilience, Self-Esteem, Depressive Symptoms, and Reliance on God in African-American Homeless Men

Empowerment has been proffered as a desirable goal for many disadvantaged populations. The process of empowerment can include encouraging disadvantaged individuals to recognize the structural factors in society (e.g., discrimination, oppression, injustice) which contribute to disadvantaged status. Two studies sought to determine the impact that recognition of oppression has on a disadvantaged individual\u27s (1) self-esteem; (2) level of depressive symptoms; (3) resilience which includes a sense of master y and optimism; (4) anger; and (5) reliance on God. These issues were investiga ted in a sample of African-American men seeking services at a soup-kitchen ministry. Perceptions of racial discrimination were marginally associated with attenuated levels of depressive symptoms. There was no evidence that perception of oppression influenced anger or self-esteem. However, belief in a just world was associated with some aspects of resilience and stronger reliance on God. Attributions to individual causes of homelessness were marginally associated with greater optimism. Those practitioners endeavoring to empower should be cautious about impairing clients\u27 belief in a just world or undermining a sense of personal control over events

Do Inner-City, African-American Males Exhibit Bad Attitudes toward Work?

Many potential employers of inner-city African-American men believe that African-American men have poor work attitudes. The investigations reported here attempted to evaluate the veridicality of this assumption. The responses of African-American men who utilize a soup-kitchen were compared with college men on a variety of attitude measures, as well as on their reactions to a scenario about a man who worked for an unfair boss and quit in response. Generally, little support for the view that innercity, African-Americans men have a predilection to presume prejudice or unfairness, or to render a favorable evaluation of quitting under unfair conditions, was found

Quantum Effects in the Spin Dynamics of the Linear Heisenberg Antiferromagnet

We present an approximate analytic expression for the dynamical spin correlation function of the S=1/2 linear Heisenberg antiferromagnet at T=0. The basis for our approach is that in zero field the spectrum is dominated by a double continuum [in (q,ω) ‐space] of triplet spin waveexcitations. The S=1/2 integrated intensity agrees very well with recent neutron scattering results on CPC, unlike the corresponding classical intensity. Moreover, the S=1/2 spectral weight function shows increasing asymmetry as q→π, a quantum effect, observable in more recent neutron scattering data. In non‐zero magnetic field, there exist two, partly overlapping, double continua, each giving rise to a peak situated at the lower boundary. The (zz component of) spectral weight function therefore has a double‐peaked structure, as observed experimentally. Theory and experiment are in apparent agreement concerning the energy difference between the peaks

Quantum Spin Dynamics of the Antiferromagnetic Linear Chain in Zero and Nonzero Magnetic Field

Spin-dynamical calculations on one-dimensional systems have relied heavily on classical (s = ∞) theories, despite abundant evidence that quantum effects can be extremely important at low temperatures. We present a new approach to the spin dynamics of the one-dimensional isotropic s=½ Heisenberg antiferromagnetic (HB AF) which does not involve the many-body techniques usually employed. It is based on analytic Bethe ansatz calculations of excitation energies and densities of states combined with finite-chain calculations of matrix elements. An important feature of our method is the use of rigorous selection rules and the introduction of new selection rules, which are valid for macroscopic systems in a magnetic field. We show that in zero field the dynamical two-spin correlation function Sμμ(q,ω) at T = 0 is governed by a two-parameter continuum of spin-wave-type excitations. In nonzero field, the longitudinal component Szz(q,ω) and the transverse components Sxx(q,ω) ≡ Syy(q,ω) behave quite differently because they are dominated by different continua of excitations. The former is characterized by a lowest excitation branch with a zero-frequency mode moving from the zone boundary (q = π) towards the zone center (q = 0) as the field increases, whereas the latter is characterized by a lowest branch with a zero frequency mode moving from q = 0 to π with increasing field. The first part of our work features an approximate analytic expression for Sμμ(q,ω) at zero temperature and in zero field. Although our expression is not rigorous, exact sum rules are violated only by a small amount, and good agreement exists with the few known exact results. Our studies are extended to nonzero temperatures by placing major reliance on exact finite-chain calculations. Our work was stimulated by recent neutron scattering experiments and is oriented towards experimental comparisons. Our result for the s=½ integrated intensity is in much better agreement with neutron scattering data on CuCl2·2N(C5D5) (CPC) than the corresponding semiclassical result. Moreover, the spectral-weight distribution in Sμμ(q,ω) shows increasing asymmetry as q→π, a quantum effect, again in agreement with more recent neutron scattering data. The second part of our work deals with the effects of an applied magnetic field. We extend the analytic work of Ishimura and Shiba to obtain expressions for the energies and densities of states of the various excitation continua. It is shown that these continua are expected to give rise to multiple structures in the scattering intensity. Our results appear to be in quantitative agreement with preliminary results of a neutron study in CPC in a field of 70 kOe, revealing anomalous scattering intensity peaks. Our results repeatedly demonstrate the inadequacy of classical spin-wave theory for this problem. They call for additional experimental studies on quasi-one-dimensional antiferromagnets to examine other unusual and interesting phenomena predicted by our approach

Magnetic Field Effects on the Spin Dynamics of the Linear Spin-1/2 Heisenberg Antiferromagnet

We present a new approach to the low temperature dynamics of a quantum Heisenberg antiferromagnetic chain, which employs a combination of techniques: exact finite chain calculations; exact Bethe Ansatz calculations; and exact sum rules and selection rules. A striking property of the selection rules is that the contribution of several classes of states to the dynamics in non-zero field for finite systems is shown to vanish in the thermodynamic limit. Many novel quantum field-dependent effects appear such as soft modes, and multiple peak structure in the structure factor, which should be experimentally observable

Quantum Spin Chains

Serious scientific interest in one-dimensional (1-D) physics arose in the early 1960’s. This interest was stimulated by exact as well as accurate numerical solutions to a variety of quantum spin chain problems [1]. The potential relevance of such solutions to real experimental systems was first demonstrated by Griffiths [2] in conjunction with workers at the Kamerlingh Onnes Laboratorium, Leiden. Theory and experiment were shown to be in excellent agreement for a naturally quasi-1-D Heisenberg spin 1/2 antiferromagnet, copper tetrammine sulphate [Cu(NH3)4SO4·H2O]. Further stimulus to the new field of quasi-1-D magnetism was provided by an annotated collection of reprinted papers on a variety of 1-D model systems, including lattice gases, dynamical disordered crystal lattices, many-fermion gases (electron gases) as well as magnets. The collection appeared in book form, and remains today an important introduction to 1-D theory [3]

Improving or Impeding? The Local & National Effects of State & Federal Regulation

The law surrounding our three focus areas — equine, agriculture, and natural resources — uniquely impacts the Kentucky economy. And regulations, at all levels, have two often competing goals that policymakers must balance: economic growth with human and environmental protection. Please join our discussion as legal scholars, practitioners, and regulators share their thoughts on the benefits and limits of regulations