The Impact of a Flexible Stern on Canoe Boat Maneuverability and Speed.

Paddle boats like canoes and kayaks draw a sinusoidal path when a linear movement is intended. The reason for this behavior is that each paddle stroke induces a lateral movement of the boat. In this study, we sought to reduce the so-called yawing motion. We therefore replaced the stiff stern by a flexible stern, which is based on the Fin Ray Effect®. We built down-scaled boat models and tested them in a water channel. The similarities between experimental and original setup were evaluated by means of a dimensional analysis. (Thermoplastic) elastomers with various flexibility were used for the stern construction. In the experiments conducted in the water channel, we determined the forces acting on the boat with different stern models. The results reveal that the flexible stern induced a torque counteracting the boat's deflection, while the stiff stern caused a torque enhancing it. A paddle boat with a flexible stern could hence be a promising new method to reduce the boat's yawing movement.

The "glucose pentagon": assessing glycemic control of patients with diabetes mellitus by a model integrating different parameters from glucose profiles.

Measuring the hemoglobin A(1c) (HbA(1c)) is the standard-of-care method to assess long-term glycemic control of patients with diabetes, describing the average glycemic level. However, the HbA(1c) does not reflect acute fluctuations in glucose levels. Variability of glycemia probably has an impact on the development of diabetes-related late complications. A novel model presented in this article combines different summary measures derived from continuously recorded glucose profiles (including parameters describing glycemic variability) and the HbA(1c). The five parameters taking into account are the axes of a "glucose pentagon." Connecting the values of these parameters provided an enclosed area of a given size. For a patient with diabetes, these parameters and the connected area describe how his or her glycemia was during the monitoring period. The area of the glucose pentagon for a patient with diabetes, divided by the standard area of healthy subjects, yields a non-dimensional characteristic value defined as the glycemic risk parameter. It is assume that this risk parameter provides a more meaningful overall description of metabolic control than the HbA(1c) alone. In addition, it might also allow a better assessment of a patient's risk for developing diabetes-related late complications in comparison to the HbA(1c) alone. Of critical importance is, of course, that the clinical relevance of the glucose pentagon is verified in adequate long-term clinical studies.

Cardiac autonomic diabetic neuropathy.

Cardiovascular autonomic diabetic neuropathy (CADN) is one of the most common diabetes-associated complications. Disturbed heart rate variability (HRV) is very often the earliest symptom, even in clinically asymptomatic patients. The following article offers a topical overview for those working or interested in the fields of diabetology and cardiology.

Invasive assessment of bacterial endotoxin and inflammatory cytokines in patients with acute heart failure.

AIMS: To test the hypothesis that during acute heart failure endotoxin might be increased in hepatic veins as a sign of bacterial or endotoxin translocation from the bowel into the blood stream. METHODS AND RESULTS: In patients with acute heart failure (NYHA IV; n=17) levels of endotoxin, soluble (s) CD14, tumor necrosis factor alpha (TNFalpha and interleukin 6 (IL6)) were measured in blood drawn from an antecubital vein on admission and compared with age-matched patients with stable chronic heart failure (n=21) and healthy volunteers (n=9). All levels were systemically elevated during acute heart failure (all P<0.05); once patients were stable enough to undergo cardiac catheterization, endotoxin was found to be significantly higher in hepatic veins (0.62+/-0.05 EU/ml) than left ventricles (0.46+/-0.04 EU/ml; P<0.05), whereas sCD14, TNFalpha and IL6 were not different between these sites. At follow-up (29+/-6 days) endotoxin but not sCD14, TNFalpha or IL-6 was significantly lower as compared to baseline (P<0.05). CONCLUSIONS: Higher levels of endotoxin in hepatic veins as compared to the left ventricle during acute heart failure are suggestive of bacterial or endotoxin translocation from the bowel into the blood stream. This may lead to new treatment strategies. The lack of difference in TNFalpha levels between the pulmonary artery and the left ventricle sheds doubt on the heart as a source of systemically elevated TNFalpha levels.