Transversality of the logarithmic divergences in the Classical Finite Temperature SU(N) Self-Energy

We show that the logarithmic divergences that appear in the classical approximation of the finite temperature SU(N) self-energy are transverse. We use the Ward identities in linear gauges and the fact that the superficial degree of divergence d of a classical diagram only depends on the number of loops l via d=2-l. We comment on the relevance of this result to the construction of a low-energy effective theory beyond HTLs.Comment: 5 pages, 1 figure, REVTE

Temperature Dependence of the QCD Coupling

We present a one-loop calculation of a gauge invariant QCD beta function. Using both momentum and temperature renormalization group equations we investigate the running coupling in the magnetic sector as a function of temperature and momentum scale. At fixed momentum scale we find that, in contrast to $\lambda\phi^4$ or QED, high-temperature QCD is strongly coupled, even after renormalization group improvement. However, if the momentum scale is changed simultaneously with temperature in a specified manner, the coupling decreases. We also point out in what regime dimensional reduction occurs. Both the cases $N_f$ smaller and larger than $\frac{11}{2} N_c$ are discussed.Comment: 10 pages, LaTeX (5 postscript figures available), ITFA-93-11,THU-93/0

The Semi-Classical Relativistic Darwin Potential for Spinning Particles in the Rest-Frame Instant Form: 2-Body Bound States with Spin 1/2 Constituents

In the semiclassical approximation of Grassmann-valued electric charges for regularizing Coulomb self-energies, we extract the unique acceleration-independent interaction hidden in any Lienard-Wiechert solution for the system of N positive-energy spinning particles plus the electromagnetic field in the radiation gauge of the rest-frame instant form. With the help of a semiclassical Foldy-Wouthuysen transformation, this allows us to find the relativistic semiclassical Darwin potential. In the 2-body case the quantization of the lowest order reproduces exactly the results from the reduction of the Bethe-Salpeter equation.Comment: 102 pages, revtex fil

Older Cancer Patients’ User Experiences With Web-Based Health Information Tools:A Think Aloud Study

Background: Health information is increasingly presented on the Internet. Several Web design guidelines for older Web users have been proposed; however, these guidelines are often not applied in website development. Furthermore, although we know that older individuals use the Internet to search for health information, we lack knowledge on how they use and evaluate Web-based health information. Objective: This study evaluates user experiences with existing Web-based health information tools among older (≥ 65 years) cancer patients and survivors and their partners. The aim was to gain insight into usability issues and the perceived usefulness of cancer-related Web-based health information tools. Methods: We conducted video-recorded think-aloud observations for 7 Web-based health information tools, specifically 3 websites providing cancer-related information, 3 Web-based question prompt lists (QPLs), and 1 values clarification tool, with colorectal cancer patients or survivors (n=15) and their partners (n=8) (median age: 73; interquartile range 70-79). Participants were asked to think aloud while performing search, evaluation, and application tasks using the Web-based health information tools. Results: Overall, participants perceived Web-based health information tools as highly useful and indicated a willingness to use such tools. However, they experienced problems in terms of usability and perceived usefulness due to difficulties in using navigational elements, shortcomings in the layout, a lack of instructions on how to use the tools, difficulties with comprehensibility, and a large amount of variety in terms of the preferred amount of information. Although participants frequently commented that it was easy for them to find requested information, we observed that the large majority of the participants were not able to find it. Conclusions: Overall, older cancer patients appreciate and are able to use cancer information websites. However, this study shows the importance of maintaining awareness of age-related problems such as cognitive and functional decline and navigation difficulties with this target group in mind. The results of this study can be used to design usable and useful Web-based health information tools for older (cancer) patients

Upper gastrointestinal symptoms, psychosocial co-morbidity and health care seeking in general practice: population based case control study

<p>Abstract</p> <p>Background</p> <p>The pathophysiology of upper gastrointestinal (GI) symptoms is still poorly understood. Psychological symptoms were found to be more common in patients with functional gastrointestinal complaints, but it is debated whether they are primarily linked to GI symptoms or rather represent motivations for health-care seeking. Purpose of our study was to compare co-morbidity, in particular psychological and social problems, between patients with and without upper GI symptoms. In addition, we investigated whether the prevalence of psychological and social problems is part of a broader pattern of illness related health care use.</p> <p>Methods</p> <p>Population based case control study based on the second Dutch National Survey of general practice (conducted in 2001). Cases (adults visiting their primary care physician (PCP) with upper GI symptoms) and controls (individuals not having any of these complaints), matched for gender, age, PCP-practice and ethnicity were compared. Main outcome measures were contact frequency, prevalence of somatic as well as psychosocial diagnoses, prescription rate of (psycho)pharmacological agents, and referral rates. Data were analyzed using odds ratios, the Chi square test as well as multivariable logistic regression analysis.</p> <p>Results</p> <p>Data from 13,389 patients with upper GI symptoms and 13,389 control patients were analyzed. Patients with upper GI symptoms visited their PCP twice as frequently as controls (8.6 vs 4.4 times/year). Patients with upper GI symptoms presented not only more psychological and social problems, but also more other health problems to their PCP (odds ratios (ORs) ranging from 1.37 to 3.45). Patients with upper GI symptoms more frequently used drugs of any ATC-class (ORs ranging from 1.39 to 2.90), including psychotropic agents. The observed differences were less pronounced when we adjusted for non-attending control patients. In multivariate regression analysis, contact frequency and not psychological or social co-morbidity was strongest associated with patients suffering from upper GI symptoms.</p> <p>Conclusion</p> <p>Patients with upper GI symptoms visit their PCP more frequently for problems of any organ system, including psychosocial problems. The relationship between upper GI symptoms and psychological problems is equivocal and may reflect increased health care demands in general.</p