12 research outputs found
Dynamics of semi-flexible polymer solutions in the highly entangled regime
We present experimental evidence that the effective medium approximation
(EMA), developed by D.C. Morse [Phys. Rev. E {\bf 63}, 031502, (2001)],
provides the correct scaling law of the macroscopic plateau modulus
(where is the contour length per
unit volume and is the persistence length) of semi-flexible polymer
solutions, in the highly entangled concentration regime. Competing theories,
including a self-consistent binary collision approximation (BCA), have instead
predicted . We have tested both the EMA and
BCA scaling predictions using actin filament (F-actin) solutions which permit
experimental control of independently of other parameters. A combination
of passive video particle tracking microrheology and dynamic light scattering
yields independent measurements of the elastic modulus and
respectively. Thus we can distinguish between the two proposed laws, in
contrast to previous experimental studies, which focus on the (less
discriminating) concentration functionality of .Comment: 4 pages, 6 figures, Phys. Rev. Lett. (accepted
The cost-effectiveness of cardiac computed tomography for patients with stable chest pain
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Effect of cinnamon on gastric emptying, arterial stiffness, postprandial lipemia, glycemia, and appetite responses to high-fat breakfast
Background: Cinnamon has been shown to delay gastric emptying of a high-carbohydrate meal and reduce
postprandial glycemia in healthy adults. However, it is dietary fat which is implicated in the etiology and is
associated with obesity, type 2 diabetes and cardiovascular disease. We aimed to determine the effect of 3 g
cinnamon (Cinnamomum zeylanicum) on GE, postprandial lipemic and glycemic responses, oxidative stress, arterial
stiffness, as well as appetite sensations and subsequent food intake following a high-fat meal.
Methods: A single-blind randomized crossover study assessed nine healthy, young subjects. GE rate of a high-fat
meal supplemented with 3 g cinnamon or placebo was determined using the 13C octanoic acid breath test.
Breath, blood samples and subjective appetite ratings were collected in the fasted and during the 360 min
postprandial period, followed by an ad libitum buffet meal. Gastric emptying and 1-day fatty acid intake
relationships were also examined.
Results: Cinnamon did not change gastric emptying parameters, postprandial triacylglycerol or glucose
concentrations, oxidative stress, arterial function or appetite (p < 0.05). Strong relationships were evident (p < 0.05)
between GE Thalf and 1-day palmitoleic acid (r = -0.78), eiconsenoic acid (r = -0.84) and total omega-3 intake (r =
-0.72). The ingestion of 3 g cinnamon had no effect on GE, arterial stiffness and oxidative stress following a HF
meal.
Conclusions: 3 g cinnamon did not alter the postprandial response to a high-fat test meal. We find no evidence
to support the use of 3 g cinnamon supplementation for the prevention or treatment of metabolic disease. Dietary
fatty acid intake requires consideration in future gastrointestinal studies.
Trial registration: Trial registration number: at http://www.clinicaltrial.gov: NCT0135028
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Gastrointestinal transit, post-prandial lipaemia and satiety following 3 days high-fat diet in men
Background/Objectives: High-fat (HF) diets of 2 weeks have been shown to accelerate gastric emptying (GE). To date, no studies have shown any alteration in GE following shorter HF diets. The aim of this study was to assess if an HF, high-energy diet of 3 days can adapt gastrointestinal (GI) transit, blood lipids and satiety. Subjects/Methods: Eleven male volunteers participated in a study consisting of three, 3-day interventions each separated by a test day. During the first intervention, volunteers recorded their diet. In the second and third interventions, volunteers repeated their food diary plus either a low-fat yogurt or HF yogurt supplement in randomized order. Test days involved measurement of GE using the 13C octanoic-acid breath-test, mouth-to-caecum transit time (MCTT) using the inulin H2 breath test and satiety using visual analogue scales. Blood samples for measurement of lipaemia were taken using a venous cannula.
Results: MCTT was different between the three test days (PŒ0.038), with the shortest MCTT following the HF intervention. GE was shortest following the HF intervention. There were no differences in satiety between the interventions. The HF intervention reduced triglycerides, total cholesterol and low-density lipoprotein cholesterol, and increased high-density lipoprotein cholesterol. Conclusion: This study shows that changes in GI transit owing to an HF diet can occur in a time period as short as 3 days