The Coupled Cluster Method in Hamiltonian Lattice Field Theory

The coupled cluster or exp S form of the eigenvalue problem for lattice Hamiltonian QCD (without quarks) is investigated. A new construction prescription is given for the calculation of the relevant coupled cluster matrix elements with respect to an orthogonal and independent loop space basis. The method avoids the explicit introduction of gauge group coupling coefficients by mapping the eigenvalue problem onto a suitable set of character functions, which allows a simplified procedure. Using appropriate group theoretical methods, we show that it is possible to set up the eigenvalue problem for eigenstates having arbitrary lattice momentum and lattice angular momentum.Comment: LaTeX, no figur

The Role Of Acceptance In Headache-Related Variables

Migraine is a neurologic disorder that causes impairment in many areas of functioning. Migraine sufferers frequently avoid environmental stimuli (triggers) they assume to be associated with migraine onset, which may inadvertently lead to an increase in the potency of some triggers and increase headache frequency over time. Headache patients who instead use acceptance strategies to limit their attempts to control or eliminate/avoid their pain may experience reduced distress and pain-related disability. Studies examining acceptance-based approaches in managing chronic pain conditions have shown favorable results of acceptance on pain intensity, reduced pain-related anxiety and avoidance, and less physical and psychological disability. However, few studies have examined the construct of acceptance among individuals with headache. In order to extend previous research on chronic pain conditions, the purpose of the present study was to investigate the relationship between psychological acceptance and headache-related variables among young adults, a population at increased risk for headache but typically without complications posed by long headache histories and medication overuse. The sample consisted of 2,005 individuals (65% female; mean age = 19.10 years [SD = 2.27]): 839 without headache (42%), 602 with migraine (30%), and 564 with tension-type headache (28%). Acceptance scores distinguished among headache diagnostic groups such that those with lower acceptance were those with more frequent and severe headache disorders. Acceptance explained 10% of the variance (p \u3c 0.001) in headache-related disability and 5% of the variance in both headache severity (p \u3c 0.001), and headache frequency (p \u3c 0.001). These proportions were much smaller but statistically significant after controlling for gender and comorbid psychiatric symptoms. Although negative associations between acceptance and the headache variables was observed, these were rather modest and indicate that the role of acceptance in headache may be different than originally hypothesized. Limitations and future directions are discussed

Preliminary test on modified clays for seawater resistant drilling fluids

The quality of a drilling fluid declines in salt water conditions. An engineered clay (HYPER clay) was developed for geosynthetic clay liners with enhanced resistance to aggressive conditions. This study investigates the potential of this superior clay for drilling fluids applied in salt water conditions. A sodium bentonite was treated with a carboxymethyl cellulose (CMC) polymer following the HYPER clay process method. Preliminary tests were performed to investigate suitability of HYPER clay for seawater resistant drilling fluids. Fluid performance was characterized by its thixotropic behavior, rheological properties (gel strength, yield point and viscosity), swell and bleeding behavior. Drilling fluid performance was analyzed at various polymer dosages and electrolyte concentrations. Polymer treatment improved the gel strength and swelling ability of the fluid, especially in electrolyte solutions. Moreover, filter press tests (API 13B-1, 76% seawater) showed that filtrate loss decreased due to polymer treatment