The QED Structure of the Photon

Measurements of the QED structure of the photon based on the reaction ee --> ee \gamma(*)(P^2)\gamma*(Q^2) --> ee mumu are discussed. This review is an update of the discussion of the results on the QED structure of the photon presented in Refs.[1], and covers the published measurements of the photon structure functions F_2, F_A nd F_B and of the differential cross-section dsig/dx for the exchange of two virtual photons.Comment: Invited talk given at the 7th International Workshop on Deep Inelastic Scattering and QCD, April 19 to 23, 1999, Zeuthen, to appear in the proceedings. 8pages 4 figure

Ischaemic heart disease in Turkish migrants with type 2 diabetes mellitus in The Netherlands: wait for the next generation?

OBJECTIVE: To study the prevalence of ischaemic heart disease in Turkish and Surinam-Asian migrants with type 2 diabetes mellitus in the Netherlands as compared with Europeans. METHODS: In a consecutive case-control study, 59 Turkish and 62 Surinam-Asian patients were compared with 185 Europeans referred to a diabetes clinic for treatment of type 2 diabetes in the period 1992 to 1998. Main outcome measures were ischaemic heart disease and its associated risk factors. RESULTS: The prevalence of ischaemic heart disease was lower (9%) in the Turks (p < 0.02), but higher (29%) in the Surinam-Asians compared with the Europeans (23%). The Turks (52 +/- 10 years) and Surinam-Asians (46 +/- 12 years) were younger than the Europeans (64 +/- 11 years, p < 0.001). Body mass index was 32 +/- 5 (p < 0.001) in the Turks, 27 +/- 5 in the Surinam-Asians (p < 0.05) and 29 +/- 5 in the Europeans. Turkish patients smoked less (23%, p < 0.05) and used less alcohol (4%, p < 0.05) than the Europeans. Proteinuria was found in 24% of the Turks (p < 0.05), 37% of the Surinam-Asians (NS) and 46% of the Europeans. In univariate analysis ischaemic heart disease was related to Turkish origin, OR 0.34 (0.14-0.83) p < 0.02, to Surinam-Asian origin, OR 1.84 (1.00-3.38) p = 0.05, and smoking, OR 1.78 (1.18-2.68) p < 0.01. Other variables were not related to ischaemic heart disease. Multivariate analysis in a model with ethnicity and smoking showed significant relations between ischaemic heart disease and Turkish ethnicity, OR 0.19 (0.06-0.65) p = 0.007, Surinam-Asian origin, OR 2.77 (1.45-5.28) p = 0.002, and smoking, OR 1.79 (1.20-2.66) p = 0.004. CONCLUSION: Type 2 diabetes mellitus in different ethnic groups results in a significant difference in incidence of ischaemic heart disease. The most remarkable finding is a low incidence of ischaemic heart disease in the Turkish patients with type 2 diabetes, independent of smoking. The high prevalence of ischaemic heart disease in young migrant Asians with diabetes is confirmed

Competing tunneling trajectories in a 2D potential with variable topology as a model for quantum bifurcations

We present a path - integral approach to treat a 2D model of a quantum bifurcation. The model potential has two equivalent minima separated by one or two saddle points, depending on the value of a continuous parameter. Tunneling is therefore realized either along one trajectory or along two equivalent paths. Zero point fluctuations smear out the sharp transition between these two regimes and lead to a certain crossover behavior. When the two saddle points are inequivalent one can also have a first order transition related to the fact that one of the two trajectories becomes unstable. We illustrate these results by numerical investigations. Even though a specific model is investigated here, the approach is quite general and has potential applicability for various systems in physics and chemistry exhibiting multi-stability and tunneling phenomena.Comment: 11 pages, 8 eps figures, Revtex-

Optimal nutrition and its potential effect on survival in critically ill patients

Optimal nutrition serves to maintain normal organ function and to preserve body energy stores to guarantee survival during times of shortage of food. Especially total body protein content is an important determinant of survival. However, recommendations about nutrition refer mostly to total energy intake with either no emphasis on total protein content or protein intake only considered as a fixed percentage of caloric intake. This paper focuses on the role of total body protein mass or lean body mass (= mass of organs and muscle) (LBM) on survival of healthy humans and critically ill patients. Recommendations on the amount of protein per kg bodyweight are made based on the scarce evidence available in humans

Glucose metabolism in chronic lung disease

Chronic disease in general induces insulin resistance on glucose metabolism on hepatic and peripheral levels. Hypoxia in healthy subjects, induced by chronic altitude exposure, stimulates glucose production with decreased hepatic insulin sesitivity, but increases peripheral insulin sensitivity. Chronic obstructive lung disease (COPID) is a chronic inflammatory disease characterised by chronic or intermittent hypoxia. Therefore theoretically, COPD can be a chronic disease with unique features in peripheral insulin sensitivity. In this literature review the available data on glucose metabolism in COPD and cystic fibrosis are discussed in relation to this potential unique feature of increased peripheral insulin sensitivity despite the existence of chronic disease. The scarce data do not refute this possibility, but better studies aimed at exploring the influence of the degree of hypoxia on peripheral insulin sensitivity in chronic lung disease are necessary to unravel the role of oxygen in the regulation of peripheral glucose metabolism. (C) 2002 Published by Elsevier Science Lt

Adipocyte-myocyte crosstalk in skeletal muscle insulin resistance; is there a role for thyroid hormone?

Purpose of review To review original research studies and reviews that present data on adipocyte-myocyte crosstalk in the development of skeletal muscle insulin resistance with a specific focus on thyroid hormone. Recent findings Adipose tissue communicates with skeletal muscle not only through free fatty acids but also through secretion of various products called adipokines. Adipokines came out as governors of insulin sensitivity and are deregulated in obesity. In addition to well known leptin, adiponectin, interleukin-6 and tumor necrosis factor-alpha, newer adipokines like retinol-binding protein 4 have been associated with insulin resistance. There is mounting evidence that not only adipose tissue but also skeletal muscle produces and secretes biologically active proteins or 'myokines' that facilitate metabolic crosstalk between organ systems. In recent years, increased expression of myostatin, a secreted anabolic inhibitor of muscle growth and development, has been associated with obesity and insulin resistance. Both hypothyroidism and hyperthyroidism affect insulin sensitivity in multiple ways that might overlap adipocyte-myocyte crosstalk. Recent studies have provided new insights in effects of processing of the parent hormone T4 to the active T3 at the level of the skeletal muscle. Summary Adipocyte-myocyte crosstalk is an important modulator in the development of skeletal muscle insulin resistance. Thyroid disorders are very common and may have detrimental effects on skeletal muscle insulin resistance, potentially by interacting with adipocyte-myocyte crosstalk