Casting propellant in rocket engine

A method is described for casting a solid propellant in the casing of a rocket engine having a continuous wall with a single opening which is formed by leaves of a material which melt at a temperature of the propellant and with curved edges concentric to the curvature of the spherical casing. The leaves are inserted into the spherical casing through the opening forming a core having a greater width than the width of the single opening and with curved peripheral edges. The cast propellant forms a solid mass and then heated to melt the leaves and provide a central opening with radial projecting flutes

Police Perceptions and Parenting Styles Among Black Parents of Miami-Dade County

A person’s perception of something or someone does not develop without external factors affecting the individual. Experiences and lessons people have learned from a young age have molded their perception of the world. One of those lessons is what is considered correct and what is not. In the Black American community, this is accompanied by the “talk”. This “talk” is shaped by past experiences with the police towards minority groups, specifically, Black Americans. This paper discusses how parenting styles, race, and authority intersect. The purpose of this paper is to examine the beginnings of one’s life, the lessons they are taught, and how parenting has affected one’s view on authority

Les recours propres à l’hypothèque immobilière en common law

L’auteur a voulu faire une étude des recours propres à l’hypothèque immobilière afin de créer une charpente pour faciliter l’étude en français de la jurisprudence se rapportant aux autres aspects des règles de fond du droit hypothécaire tels que la nature des secondes hypothèques ou la vente du droit de rachat ou le classement des hypothèques. A cette fin, l’auteur a eu un souci tout particulier de s’assurer que les mots ou expressions proprement juridiques, façonnés pour exposer ce secteur du droit, rendent d ’une manière juste les concepts du droit anglais. L ’article consiste en une étude, d ’une part du droit de rachat qui constitue le recours fondamental du débiteur hypothécaire, et d’autre part, de l’action en forclusion, la vente judiciaire, la vente extrajudiciaire, l’action personnelle sur l’engagement et la prise de possession, qui représentent l’ensemble des recours ouverts au créancier hypothécaire

Modification Of The Devonshire Formula For The Thermal Accommodation Coefficient Of Helium On Tungsten

The thermal accommodation coefficients (a.c.) of 3He and of 4He on clean tungsten were calculated using the Devonshire formula for temperatures between 70 and 600°K using realistic Morse potential parameters. The calculated a.c. values for 3He and 4He and the calculated ratios of the 4He to 3He values are compared with experimental data. The agreement is satisfactory if allowance is made for the error in the transition probability calculation used in the Devonshire formula

Turbulent transport in tokamak plasmas with rotational shear

Nonlinear gyrokinetic simulations have been conducted to investigate turbulent transport in tokamak plasmas with rotational shear. At sufficiently large flow shears, linear instabilities are suppressed, but transiently growing modes drive subcritical turbulence whose amplitude increases with flow shear. This leads to a local minimum in the heat flux, indicating an optimal E x B shear value for plasma confinement. Local maxima in the momentum fluxes are also observed, allowing for the possibility of bifurcations in the E x B shear. The sensitive dependence of heat flux on temperature gradient is relaxed for large flow shear values, with the critical temperature gradient increasing at lower flow shear values. The turbulent Prandtl number is found to be largely independent of temperature and flow gradients, with a value close to unity.Comment: 4 pages, 5 figures, submitted to PR

Transition to subcritical turbulence in a tokamak plasma

Tokamak turbulence, driven by the ion-temperature gradient and occurring in the presence of flow shear, is investigated by means of local, ion-scale, electrostatic gyrokinetic simulations (with both kinetic ions and electrons) of the conditions in the outer core of the Mega-Ampere Spherical Tokamak (MAST). A parameter scan in the local values of the ion-temperature gradient and flow shear is performed. It is demonstrated that the experimentally observed state is near the stability threshold and that this stability threshold is nonlinear: sheared turbulence is subcritical, i.e. the system is formally stable to small perturbations, but, given a large enough initial perturbation, it transitions to a turbulent state. A scenario for such a transition is proposed and supported by numerical results: close to threshold, the nonlinear saturated state and the associated anomalous heat transport are dominated by long-lived coherent structures, which drift across the domain, have finite amplitudes, but are not volume filling; as the system is taken away from the threshold into the more unstable regime, the number of these structures increases until they overlap and a more conventional chaotic state emerges. Whereas this appears to represent a new scenario for transition to turbulence in tokamak plasmas, it is reminiscent of the behaviour of other subcritically turbulent systems, e.g. pipe flows and Keplerian magnetorotational accretion flows.Comment: 16 pages, 5 figures, accepted to Journal of Plasma Physic

Tensin1 expression and function in chronic obstructive pulmonary disease

open access articleChronic obstructive pulmonary disease (COPD) constitutes a major cause of morbidity and mortality. Genome wide association studies have shown significant associations between airflow obstruction or COPD with a non-synonymous SNP in the TNS1 gene, which encodes tensin1. However, the expression, cellular distribution and function of tensin1 in human airway tissue and cells are unknown. We therefore examined these characteristics in tissue and cells from controls and people with COPD or asthma. Airway tissue was immunostained for tensin1. Tensin1 expression in cultured human airway smooth muscle cells (HASMCs) was evaluated using qRT-PCR, western blotting and immunofluorescent staining. siRNAs were used to downregulate tensin1 expression. Tensin1 expression was increased in the airway smooth muscle and lamina propria in COPD tissue, but not asthma, when compared to controls. Tensin1 was expressed in HASMCs and upregulated by TGFβ1. TGFβ1 and fibronectin increased the localisation of tensin1 to fibrillar adhesions. Tensin1 and α-smooth muscle actin (αSMA) were strongly co-localised, and tensin1 depletion in HASMCs attenuated both αSMA expression and contraction of collagen gels. In summary, tensin1 expression is increased in COPD airways, and may promote airway obstruction by enhancing the expression of contractile proteins and their localisation to stress fibres in HASMCs