Exogenous carbohydrate and regulation of muscle carbohydrate utilisation during exercise

Carbohydrates (CHO) are one of the fundamental energy sources during prolonged steady state and intermittent exercise. The consumption of exogenous CHO during exercise is common place, with the aim to enhance sporting performance. Despite the popularity around exogenous CHO use, the process by which CHO is regulated from intake to its use in the working muscle is still not fully appreciated. Recent studies utilizing the hyperglycaemic glucose clamp technique have shed light on some of the potential barriers to CHO utilisation during exercise. The present review addresses the role of exogenous CHO utilisation during exercise, with a focus on potential mechanisms involved, from glucose uptake to glucose delivery and oxidation at the different stages of regulation.Narrative review.A number of potential barriers were identified, including gastric emptying, intestinal absorption, blood flow (splanchnic and muscle), muscle uptake and oxidation. The relocation of glucose transporters plays a key role in the regulation of CHO, particularly in epithelial cells and subsequent transport into the blood. Limitations are also apparent when CHO is infused, particularly with regards to blood flow and uptake within the muscle.We highlight a number of potential barriers involved with the regulation of both ingested and infused CHO during exercise. Future work on the influence of longitudinal training within the regulation processes (such as the gut) is warranted to further understand the optimal type, dose and method of CHO delivery to enhance sporting performance

The Adiabatic Matching Section Solution for the Source Injector

Typical designs for a Heavy Ion Fusion Power Plant require the source injector to deliver 100 beams, packed into an array with a spacing of 7 cm. When designing source injectors using a single large aperture source for each beam, the emitter surfaces are packed into an array with a spacing of 30 cm. Thus, the matching section of the source injector must not only prepare the beam for transport in a FODO lattice, but also funnel the beams together. This can be accomplished by an ESQ matching section in which each beam travels on average at a slight angle to the axis of the quadrupoles and uses the focussing effect of the FODO lattice to maintain the angle. At the end of the matching section, doublet steering is used to bring the beams parallel to each other for injection into the main accelerator. A specific solution of this type for an 84-beam source injector is presented. PACS: 41.75.Ak,41.85.Ar, 41.85.J

The Adiabatic Matching Section Solution for the Source Injector

Typical designs for a Heavy Ion Fusion Power Plant require the source injector to deliver 100 beams, packed into an array with a spacing of 7 cm. When designing source injectors using a single large aperture source for each beam, the emitter surfaces are packed into an array with a spacing of 30 cm. Thus, the matching section of the source injector must not only prepare the beam for transport in a FODO lattice, but also funnel the beams together. This can be accomplished by an ESQ matching section in which each beam travels on average at a slight angle to the axis of the quadrupoles and uses the focussing effect of the FODO lattice to maintain the angle. At the end of the matching section, doublet steering is used to bring the beams parallel to each other for injection into the main accelerator. A specific solution of this type for an 84-beam source injector is presented. PACS: 41.75.Ak,41.85.Ar, 41.85.J

The Nanoscale Structure of the B and I-w Phases in Yttrium and Erbium SiAlONs

High resolution electron microscopy has been used to examine the nanoscale structure of the related B and I-w phases in Y and Er SiAlONs. B-phase was found to consist of nanoscale domains with a lower symmetry than the average hexagonal symmetry. The monoclinic cell of I-w can be clearly imaged by HREM and work is in progress to use these images in the determination of atomic positions in the unit cell. One consequence of the ordered structure of I-w is the possibility of forming domain boundaries, and two of the three possible types of domain boundaries have now been imaged using HREM

The influence of dietary carbohydrate and pre-exercise glucose consumption on supramaximal intermittent exercise performance

The present study examined whether a pre-exercise consumption of glucose by subjects having adhered to a 3-day low carbohydrate (CHO) or normal CHO diet would influence supramaximal intermittent exercise performance. Sixteen moderately active men volunteers (mean(s.d.) age 20.0(1.3) years) agreed to undertake three exercise tests over an 8-day period; in addition to completing a VO2max test, the subjects performed two identical maximal interval tests (MIT(1) and MIT(2)). Periods of 3 days separated each of the three tests. The interval tests involved five 60-s 'all-out' cycling bouts working against a resistance of 0.075 kg kg(-1) body mass; each bout was separated by 5 min of passive recovery. For 3 days preceding the first interval test (MIT(1)), all subjects adhered to a 'moderate' CHO diet which comprised 59.1% (approximately 4.1 g kg(-1) body mass) of the daily energy intake as CHO. Following MIT(1) and for 3 days before MIT(1) subjects were randomly assigned to follow either a moderate CHO diet (60.8%) or a low CHO diet (14.4% or 1.1 g kg(-1) body mass). All food and drink consumed during the experimental period was weighed and recorded for later dietary analysis. One hour before MIT(2), eight subjects were administered (in single blind fashion) a 15% glucose solution (1 g kg(-1) body mass) while the other eight subjects consumed a low-energy sweetened placebo. During both interval tests, values of work, exercise VO2, plasma glucose, plasma lactate and venous blood pH were statistically analysed. No changes in performance between MIT(1) and MIT(2) across conditions were found (P > 0.05). However, those subjects who consumed the glucose solution before MIT(1) (irrespective of their dietary CHO intake) consumed significantly less oxygen during exercise than those who had been given the placebo solution (P < 0.05). While these findings question the ergogenic potential of consuming glucose before supramaximal exercise, the VO2 data implicate a possible shift in substrate utilization during repeated sprint exercise after pre-exercise glucose ingestion

Male circumcision for HIV prevention in PNG: a summary of research evidence and recommendations for public health

In 2005, a clinical trial in South Africa found that circumcision of young men could reduce their risk of acquiring HIV (human immunodeficiency virus) infection by over 60%. In the following year, two more trials in Africa confirmed this finding, leading the World Health Organization to recommend male circumcision as a public health strategy for HIV prevention in high-incidence countries. In order to inform public health policy in Papua New Guinea (PNG), two major research projects were initiated with the goals of investigating the status of penile cutting practices and assessing understandings, acceptability, feasibility and cost-effectiveness of male circumcision for HIV prevention. In addition, behavioural surveillance surveys systematically asked questions on penile cutting practices and an ethnographic literature review informed historical perspectives of penile cutting in PNG. Key findings from these research activities were presented at a National Policy Forum on Male Circumcision for HIV Prevention held in Port Moresby in November 2011. The Forum made three key recommendations: (1) the formation of a joint National Department of Health/National AIDS Council Secretariat Policy Committee on male circumcision; (2) the establishment of an integrated harm reduction program; and (3) that future policy on wide-scale roll-out of male circumcision for HIV prevention in PNG be informed by a combination of data from (a) male circumcision intervention pilot programs and (b) research on the potential protective effect of other forms of penile cutting