The effect of ethnicity on the vascular responses to cold exposure of the extremities

This is an accepted manuscript of an article published by Springer in European Journal of Applied Physiology on 01/08/2014, available online: https://doi.org/10.1007/s00421-014-2962-2 The accepted version of the publication may differ from the final published version.© 2014, Springer-Verlag Berlin Heidelberg. Purpose: Cold injuries are more prevalent in individuals of African descent (AFD). Therefore, we investigated the effect of extremity cooling on skin blood flow (SkBF) and temperature (Tsk) between ethnic groups.Methods: Thirty males [10 Caucasian (CAU), 10 Asian (ASN), 10 AFD] undertook three tests in 30 °C air whilst digit Tsk and SkBF were measured: (i) vasomotor threshold (VT) test—arm immersed in 35 °C water progressively cooled to 10 °C and rewarmed to 35 °C to identify vasoconstriction and vasodilatation; (ii) cold-induced vasodilatation (CIVD) test—hand immersed in 8 °C water for 30 min followed by spontaneous warming; (iii) cold sensitivity (CS) test—foot immersed in 15 °C water for 2 min followed by spontaneous warming. Cold sensory thresholds of the forearm and finger were also assessed.Results: In the VT test, vasoconstriction and vasodilatation occurred at a warmer finger Tsk in AFD during cooling [21.2 (4.4) vs. 17.0 (3.1) °C, P = 0.034] and warming [22.0 (7.9) vs. 12.1 (4.1) °C, P = 0.002] compared with CAU. In the CIVD test, average SkBF during immersion was greater in CAU [42 (24) %] than ASN [25 (8) %, P = 0.036] and AFD [24 (13) %, P = 0.023]. Following immersion, SkBF was higher and rewarming faster in CAU [3.2 (0.4) °C min−1] compared with AFD [2.5 (0.7) °C min−1, P = 0.037], but neither group differed from ASN [3.0 (0.6) °C min−1]. Responses to the CS test and cold sensory thresholds were similar between groups.Conclusion: AFD experienced a more intense protracted finger vasoconstriction than CAU during hand immersion, whilst ASN experienced an intermediate response. This greater sensitivity to cold may explain why AFD are more susceptible to cold injuries.Published versio

Role of cyclooxygenase in the vascular response to locally delivered acetylcholine in Caucasian and African descent individuals

This is an accepted manuscript of an article published by Elsevier in Microvascular Research on 17/01/2017, available online: https://doi.org/10.1016/j.mvr.2017.01.005 The accepted version of the publication may differ from the final published version.© 2017 Elsevier Inc. Introduction Individuals of African descent (AFD) are more susceptible to non-freezing cold injury (NFCI) compared with Caucasian individuals (CAU). Vasodilatation to acetylcholine (ACh) is lower in AFD compared with CAU in the non-glabrous foot and finger skin sites; the reason for this is unknown. Prostanoids are responsible, in part, for the vasodilator response to ACh, however it is not known whether the contribution differs between ethnicities. Methods 12 CAU and 12 AFD males received iontophoresis of ACh (1 w/v%) on non-glabrous foot and finger skin sites following placebo and then aspirin (600 mg, single blinded). Aspirin was utilised to inhibit prostanoid production by inhibiting the cyclooxygenase (COX) enzyme. Laser Doppler flowmetry was utilised to measure changes in skin blood flow. Results Not all participants could receive iontophoresis charge due to high skin resistance; these participants were therefore excluded from the analyses. Foot: ACh elicited greater maximal vasodilatation in CAU than AFD following placebo (P = 0.003) and COX inhibition (COXib) (P < 0.001). COXib did not affect blood flow responses in AFD, but caused a reduction in the area under the curve for CAU (P = 0.031). Finger: ACh elicited a greater maximal vasodilatation in CAU than AFD following placebo (P = 0.013) and COXib (P = 0.001). COXib tended to reduce the area under the curve in AFD (P = 0.053), but did not affect CAU. Conclusions CAU have a greater endothelial reactivity than AFD in both foot and finger skin sites irrespective of COXib. It is concluded that the lower ACh-induced vasodilatation in AFD is not due to a compromised COX pathway.Published versio

Unique Characteristics of Liquid Metal Extended Meniscus Evaporation

The research in this dissertation addresses the steady evaporation of a capillary pore with a liquid metal working fluid. First, the interline region of an extended meniscus thin film is considered for the unique physical case of a liquid metal. A new thin film evaporation model is presented that captures the unsimplified dispersion force along with an electronic disjoining pressure component that is unique to liquid metals. The resulting nonlinear 4th-order ODE is solved using an implicit orthogonal collocation technique along with the Levenberg-Marquardt method. Results show that the electronic component of the disjoining pressure should be considered when modeling liquid metal extended meniscus evaporation for a wide range of work function boundary values, which represent physical properties of different liquid metals. For liquid sodium, as an example test material, variation in the work function produces order-of-magnitude differences in the film thickness and evaporation profile. Second, the extended meniscus thin film model is spliced with a CFD model of the evaporating bulk meniscus. The result is a multiscale model of the total evaporating capillary meniscus with a nonisothermal interface and non-equilibrium evaporation. Integration of the evaporative mass flux across the total meniscus surface area produces total capillary evaporative mass flow rates and enables comparisons between electronic disjoining pressure states. The clear trend from these comparisons is that a larger electronic component of the disjoining pressure leads towards larger extended meniscus thin film surface area, larger total capillary meniscus surface area, and larger net evaporative mass flow rate (which corresponds with larger heat flow rate, as well). Finally, an outline is presented of the scope of the general problem in the application of nonlinear stability theory to a liquid metal evaporating thin film

Abundance and Density of Mountain Plover (\u3ci\u3eCharadrius montanus\u3c/i\u3e) and Burrowing Owl (\u3ci\u3eAthene cunicularia\u3c/i\u3e) in Eastern Colorado

Because of continental-scale declines of grassland birds over the past century, conservation agendas are focused on increasing understanding of grassland bird ecology and habitat associations. Shortgrass prairie is a unique grassland ecosystem maintained, in part, by Black-tailed Prairie Dogs (Cynomys ludovicianus). The Mountain Plover (Charadrius montanus) and western Burrowing Owl (Athene cunicularia hypugaea) are species of conservation concern known to be associated with prairie dog colonies. We estimated abundance of Mountain Plovers and Burrowing Owls in three habitats within the Colorado shortgrass prairie ecosystem— prairie dog colonies, grassland not occupied by prairie dogs, and dryland agriculture. Further, we investigated habitat associations of Mountain Plovers and Burrowing Owls at multiple landscape scales. We estimated 8,577 Mountain Plovers (95% CI: 7,511–35,130) and 3,554 Burrowing Owls (95% CI: 3,298–8,445) in eastern Colorado. Mountain Plover density on prairie dog colony plots (ˆD = 2.26 birds per 100 ha, 95% CI: 2.15–5.13) was significantly higher than densities on either grassland (ˆD = 0.23, 95% CI: 0.17–1.76) or dryland- agriculture plots (ˆD = 0.45, 95% CI: 0.44–0.53). Burrowing Owl density on prairie dog colony plots (ˆD = 3.04 birds per 100 ha, 95% CI: 2.82–6.92) was significantly higher than densities on either grassland (ˆD = 0.044, 95% CI: 0.041–0.12) or dryland-agriculture plots (no Burrowing Owls detected). Our results suggest that increased prairie dog colonies would positively influence the abundance of Mountain Plover and Burrowing Owl

PROGRESS RELATING TO CIVILIAN APPLICATIONS DURING JULY 1958

Data are given on the thermal ccnductivity of Ti--6 wt. % Al--4 wt.% V. The creep strength of 15% cold-worked Zircaloy-2 is being determined for reactor components in the 290 to 400 deg C range. Nine serles of high-strength corrosion- resistant Zr alloys were prepared and corrosion tested. Results are included. The fabrication of Al-U alloys for uses in various reactors is presented. The development of a natural-U fuel alloy with improved corrosion resistance is presented. Results of corrosion tests on the natural--U alloy are presented. A study is presented to investigate the possibilities of applying a thin protectlve coating of Mo on the interior surfaces of the reactor system by electroless and vapor-plating techniques. An irradiation-damage program to detcrmine the extent of damage to type 347 stainless steel in iast-neutron fluxes in the core of the ETR is presented. The properties of the high-niobium portion of the Nb-U constitution diagram are presented. The development of Th-U alloys with increased irradiation stability and corrosion resistance is presented. Dispersion-type fuel specimens containing 24 wt.% fully enriched UC and UN dispersed in a l8 wt.% Cr14 wt.% Ni-2.5 wt.% Mo--balance Fe matrix and clad with type 318 stainless steel were fabricated for irradiation testing. Gas-pressure bonding is being investigated as a technique for the cladding and bonding of Nb and Mo fuel elements. Corrosion testing of Ti in Darex Process dissolver solution is presented. Studies were continued on ways of preventing stress- corrosion cracking of Carpenter 20 Cb in the Sulfex-Thorex system. A run is under way in a new molten-salt composition (62 M% NaF-38 M% ZrF/sub 4/). Specimens of INOR-1 and INOR-8, Hastelloy B, and type S-816 are being tested. A program is presented for the preparation of as-cast irradiation-test specimens of UC and the determination of some physical properties of UC. The postirradiation examination of twelve Th-11 wt.% U speci mens irradiated in two capsule trains has been completed. Creep data are presented on thermally degassed fine-grained sintered Ta sheet tested at 1200 F in a He atmosphere. A program to investigate the effects of reactor radiations on clad graphite specimens is in progress. The current work on the Nuclear Merchant Ship Reactor Program is primarily concerned with the development of fabrication techniques for UOsub 2/- containing fuel pins for a dynamic loop test at the MTR. (For preceding period see BMI-1273.) (W.L.H.

Progress Relating to Civilian Applications During August 1961

Progress is reported on development studies on reactor materials and components, fuels, fuel elements, gaspressure bonding of ceramic fuel elements, uranium carbides, growth of UO/sub 2/ single crystals, radioisotope and radiation applications, materials evaluations, coated-particle fuel materials, corrosion in fiuoride-volatility processes, cold-bonding processes, radiation effects on MGCR fuel materials, radiation effects on SM-2 fuels, gas-cooled reactor program, and gas-pressure bonding of beryllium-clad fuel elements. (B.O.G.

Milk: the new sports drink? A Review

There has been growing interest in the potential use of bovine milk as an exercise beverage, especially during recovery from resistance training and endurance sports. Based on the limited research, milk appears to be an effective post-resistance exercise beverage that results in favourable acute alterations in protein metabolism. Milk consumption acutely increases muscle protein synthesis, leading to an improved net muscle protein balance. Furthermore, when post-exercise milk consumption is combined with resistance training (12 weeks minimum), greater increases in muscle hypertrophy and lean mass have been observed. Although research with milk is limited, there is some evidence to suggest that milk may be an effective post-exercise beverage for endurance activities. Low-fat milk has been shown to be as effective, if not more effective, than commercially available sports drinks as a rehydration beverage. Milk represents a more nutrient dense beverage choice for individuals who partake in strength and endurance activities, compared to traditional sports drinks. Bovine low-fat fluid milk is a safe and effective post exercise beverage for most individuals, except for those who are lactose intolerant. Further research is warranted to better delineate the possible applications and efficacy of bovine milk in the field of sports nutrition

Effect of carbohydrate-protein supplement timing on acute exercise-induced muscle damage

<p>Abstract</p> <p>Purpose</p> <p>To determine if timing of a supplement would have an effect on muscle damage, function and soreness.</p> <p>Methods</p> <p>Twenty-seven untrained men (21 ± 3 yrs) were given a supplement before or after exercise. Subjects were randomly assigned to a pre exercise (n = 9), received carbohydrate/protein drink before exercise and placebo after, a post exercise (n = 9), received placebo before exercise and carbohydrate/protein drink after, or a control group (n = 9), received placebo before and after exercise. Subjects performed 50 eccentric quadriceps contractions on an isokinetic dynamometer. Tests for creatine kinase (CK), maximal voluntary contraction (MVC) and muscle soreness were recorded before exercise and at six, 24, 48, 72, and 96 h post exercise. Repeated measures ANOVA were used to analyze data.</p> <p>Results</p> <p>There were no group by time interactions however, CK significantly increased for all groups when compared to pre exercise (101 ± 43 U/L) reaching a peak at 48 h (661 ± 1178 U/L). MVC was significantly reduced at 24 h by 31.4 ± 14.0%. Muscle soreness was also significantly increased from pre exercise peaking at 48 h.</p> <p>Conclusion</p> <p>Eccentric exercise caused significant muscle damage, loss of strength, and soreness; however timing of ingestion of carbohydrate/protein supplement had no effect.</p