Critical Exponents of the 3D Ising Universality Class From Finite Size Scaling With Standard and Improved Actions

We propose a method to obtain an improved Hamiltonian (action) for the Ising universality class in three dimensions. The improved Hamiltonian has suppressed leading corrections to scaling. It is obtained by tuning models with two coupling constants. We studied three different models: the +1,-1 Ising model with nearest neighbour and body diagonal interaction, the spin-1 model with states 0,+1,-1, and nearest neighbour interaction, and phi**4-theory on the lattice (Landau-Ginzburg Hamiltonian). The remarkable finite size scaling properties of the suitably tuned spin-1 model are compared in detail with those of the standard Ising model. Great care is taken to estimate the systematic errors from residual corrections to scaling. Our best estimates for the critical exponents are nu= 0.6298(5) and eta= 0.0366(8), where the given error estimates take into account the statistical and systematic uncertainties.Comment: 55 pages, 12 figure

Effective Field Theories

Effective field theories encode the predictions of a quantum field theory at low energy. The effective theory has a fairly low ultraviolet cutoff. As a result, loop corrections are small, at least if the effective action contains a term which is quadratic in the fields, and physical predictions can be read straight from the effective Lagrangean. Methods will be discussed how to compute an effective low energy action from a given fundamental action, either analytically or numerically, or by a combination of both methods. Basically,the idea is to integrate out the high frequency components of fields. This requires the choice of a "blockspin",i.e. the specification of a low frequency field as a function of the fundamental fields. These blockspins will be the fields of the effective field theory. The blockspin need not be a field of the same type as one of the fundamental fields, and it may be composite. Special features of blockspins in nonabelian gauge theories will be discussed in some detail. In analytical work and in multigrid updating schemes one needs interpolation kernels \A from coarse to fine grid in addition to the averaging kernels $C$ which determines the blockspin. A neural net strategy for finding optimal kernels is presented. Numerical methods are applicable to obtain actions of effective theories on lattices of finite volume. The constraint effective potential) is of particular interest. In a Higgs model it yields the free energy, considered as a function of a gauge covariant magnetization. Its shape determines the phase structure of the theory. Its loop expansion with and without gauge fields can be used to determine finite size corrections to numerical data.Comment: 45 pages, 9 figs., preprint DESY 92-070 (figs. 3-9 added in ps format

Cross-sectional analysis of baseline differences of candidates for rotator cuff surgery: a sex and gender perspective

<p>Abstract</p> <p>Background</p> <p>The word "sex" refers to biological differences between men and women. Gender refers to roles, behaviors, activities, and attributes that a given society considers appropriate for men and women. Traditionally, treatment decisions have been based on patient's sex without including the gender. Assessment of disability secondary to musculoskeletal problems would not be complete or accurate unless potentially relevant biological and non-biological aspects of being a man or woman are taken into consideration. The purposes of this study were to: 1) investigate the difference in pre-operative characteristics between men and women who were candidates for rotator cuff surgery; and, 2) assess the relationship between level of disability and factors that represent sex and factors that signify gender.</p> <p>Method</p> <p>This was a cross-sectional study. The primary outcome measure of disability was a disease-specific outcome measure, the Western Ontario Rotator Cuff (WORC) index, and independent variables were sex, age, hand dominance, shoulder side involvement, BMI, co-morbidity, medication use, work status, smoking habits, strength, range of motion, level of pathology, concurrent osteoarthritis, expectations for recovery, and participation restriction. Parametric, non-parametric, univariable, subgroup, and multivariable analyses were conducted.</p> <p>Results</p> <p>One hundred and seventy patients were included in the study. The mean age was 57 ± 11, 85 were females. Women reported higher levels of disability despite similar or lower levels of pathology. Scores of the WORC were strongly influenced by factors that represented "gender" such as participation restriction (F = 28.91, p < 0.0001) and expectations for improved activities of daily living (F = 5.80, p = 0.004). Painfree combined range of motion, which represented an interaction between "sex" and "gender" was also associated with disability after being adjusted for all other relevant baseline factors (F = 25.82, p < 0.0001).</p> <p>Conclusion</p> <p>Gender-related factors such as expectations and participation limitations have an independent impact on disability in men and women undergoing rotator cuff related surgery.</p