Hot filament technique for measuring the thermal conductivity of molten lithium fluoride

Molten salts, such as lithium fluoride, are attractive candidates for thermal energy storage in solar dynamic space power systems because of their high latent heat of fusion. However, these same salts have poor thermal conductivities which inhibit the transfer of heat into the solid phase and out of the liquid phase. One concept for improving the thermal conductivity of the thermal energy storage system is to add a conductive filler material to the molten salt. High thermal conductivity pitch-based graphite fibers are being considered for this application. Although there is some information available on the thermal conductivity of lithium fluoride solid, there is very little information on lithium fluoride liquid, and no information on molten salt graphite fiber composites. This paper describes a hot filament technique for determining the thermal conductivity of molten salts. The hot filament technique was used to find the thermal conductivity of molten lithium fluoride at 930 C, and the thermal conductivity values ranged from 1.2 to 1.6 W/mK. These values are comparable to the slightly larger value of 5.0 W/mK for lithium fluoride solid. In addition, two molten salt graphite fiber composites were characterized with the hot filament technique and these results are also presented

CR-Invariants and the Scattering Operator for Complex Manifolds with Boundary

The purpose of this paper is to describe certain CR-covariant differential operators on a strictly pseudoconvex CR manifold $M$ as residues of the scattering operator for the Laplacian on an ambient complex K\"{a}hler manifold $X$ having $M$ as a `CR-infinity.' We also characterize the CR $Q$-curvature in terms of the scattering operator. Our results parallel earlier results of Graham and Zworski \cite{GZ:2003}, who showed that if $X$ is an asymptotically hyperbolic manifold carrying a Poincar\'{e}-Einstein metric, the $Q$-curvature and certain conformally covariant differential operators on the `conformal infinity' $M$ of $X$ can be recovered from the scattering operator on $X$. The results in this paper were announced in \cite{HPT:2006}.Comment: 32 page

New insights into the biomechanics of Legg-Calvé-Perthes’ disease: The role of epiphyseal skeletal immaturity in vascular obstruction

ObjectivesLegg–Calvé–Perthes’ disease (LCP) is an idiopathic osteonecrosis of the femoral head that is most common in children between four and eight years old. The factors that lead to the onset of LCP are still unclear; however, it is believed that interruption of the blood supply to the developing epiphysis is an important factor in the development of the condition.MethodsFinite element analysis modelling of the blood supply to the juvenile epiphysis was investigated to understand under which circumstances the blood vessels supplying the femoral epiphysis could become obstructed. The identification of these conditions is likely to be important in understanding the biomechanics of LCP.ResultsThe results support the hypothesis that vascular obstruction to the epiphysis may arise when there is delayed ossification and when articular cartilage has reduced stiffness under compression.ConclusionThe findings support the theory of vascular occlusion as being important in the pathophysiology of Perthes disease

Sources of sport confidence, imagery type and performance among competitive athletes: The mediating role of sports confidence

Aim: This study explored the mediating role of sport confidence upon (1) sources of sport confidence-performance relationship and (2) imagery-performance relationship. Methods: Participants were 157 competitive athletes who completed state measures of confidence level/sources, imagery type and performance within one hour after competition. Results: Among the current sample, confirmatory factor analysis revealed appropriate support for the nine-factor SSCQ and the five-factor SIQ. Mediational analysis revealed that sport confidence had a mediating influence upon the achievement source of confidence-performance relationship. In addition, both cognitive and motivational imagery types were found to be important sources of confidence, as sport confidence mediated imagery type-performance relationship. Conclusion: Findings indicated that athletes who construed confidence from their own achievements and report multiple images on a more frequent basis are likely to benefit from enhanced levels of state sport confidence and subsequent performance

Sources of sport confidence, imagery type and performance among competitive athletes: The mediating role of sports confidence

Aim: This study explored the mediating role of sport confidence upon (1) sources of sport confidence-performance relationship and (2) imagery-performance relationship. Methods: Participants were 157 competitive athletes who completed state measures of confidence level/sources, imagery type and performance within one hour after competition. Results: Among the current sample, confirmatory factor analysis revealed appropriate support for the nine-factor SSCQ and the five-factor SIQ. Mediational analysis revealed that sport confidence had a mediating influence upon the achievement source of confidence-performance relationship. In addition, both cognitive and motivational imagery types were found to be important sources of confidence, as sport confidence mediated imagery type-performance relationship. Conclusion: Findings indicated that athletes who construed confidence from their own achievements and report multiple images on a more frequent basis are likely to benefit from enhanced levels of state sport confidence and subsequent performance

An off-the-shelf sensor for colourimetric detection of sulfide

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record .The cheap, accessible spiropyran nitroBIPS is a sensitive, selective colourimetric sensor for quantitative determination of sulfide in aqueous media at neutral pH

The Effect of GnRH at Time of Insemination on Initiation of LH Pulses and Subsequent Progesterone

Research has indicated that luteinizing hormone (LH) pulses play a vital role in corpus luteum (CL) formation and subsequent progesterone concentrations. Therefore, our objectives were to determine: 1) when LH pulses begin following onset of estrus, 2) the effect an injection of gonadotropin releasing hormone (GnRH) would have on initiation of LH pulses, and 3) the effect LH pulse initiation had on subsequent plasma progesterone concentrations. Cows were synchronized with the Select Synch + Controlled Internal Drug Releasing device (CIDR) protocol (d -7 100 μg GnRH and CIDR; d 0 25 mg prostaglandin (PG) and removal of CIDR; estrus detected with HeatWatch). Following detection in estrus, a jugular catheter was inserted in each cow (n = 10). Based on initiation of estrus, cows were allotted into two treatments: 1) GnRH given 12 h (12.5 ± 1.2 h) after the initiation of estrus (n = 5; 100 μg) and 2) Control (n = 5). Blood samples were collected at 15-min intervals for 6 h at 12 h (bleed 1), 26 h (bleed 2), 40 h (bleed 3), 54 h (bleed 4), and 68 h (bleed 5) after the onset of estrus. The interval from onset of estrus to bleed 1 and ovulation was similar between treatments. The GnRH cows tended to have a greater area under the LH curve for bleed 1 compared to control cows. No differences were detected in bleeds 2, 3, 4, or 5. Average concentration of LH for GnRH cows in bleed 1 tended to be greater than control. No differences were detected in bleeds 2, 3, 4, or 5. No differences were detected in pulse frequency between treatments in bleeds 1, 3, 4, or 5, but in bleed 2, control tended to have more pulses than GnRH (2.5 ± 0.5 vs 1.4 ± 0.4). The GnRH-treated cows tended to have greater subsequent progesterone concentrations; however, GnRH-treated cows that had no LH pulses during bleed 2 had lower progesterone concentrations than cows with pulses (control or GnRH). In summary, injecting cows with GnRH approximately 12 h after the onset of estrus tended to reduce LH pulses 26-32 h following initiation of estrus, and elimination of LH pulses between 26-32 h resulted in decreased concentrations of progesterone during the subsequent cycle

A finite element based formulation for sensitivity studies of piezoelectric systems

Sensitivity Analysis is a branch of numerical analysis which aims to quantify the affects that variability in the parameters of a numerical model have on the model output. A finite element based sensitivity analysis formulation for piezoelectric media is developed here and implemented to simulate the operational and sensitivity characteristics of a piezoelectric based distributed mode actuator (DMA). The work acts as a starting point for robustness analysis in the DMA technology