64,691 research outputs found
Cheban loops
Left Cheban loops are loops that satisfy the identity x(xy.z) = yx.xz. Right
Cheban loops satisfy the mirror identity {(z.yx)x = zx.xy}. Loops that are both
left and right Cheban are called Cheban loops. Cheban loops can also be
characterized as those loops that satisfy the identity x(xy.z) = (y.zx)x. These
loops were introduced in Cheban, A. M. Loops with identities of length four and
of rank three. II. (Russian) General algebra and discrete geometry, pp.
117-120, 164, "Shtiintsa", Kishinev, 1980. Here we initiate a study of their
structural properties. Left Cheban loops are left conjugacy closed. Cheban
loops are weak inverse property, power associative, conjugacy closed loops;
they are centrally nilpotent of class at most two.Comment: 6 page
Holddown arm release mechanism used on Saturn vehicles
With the development of the Saturn launch vehicle, it became mandatory to develop a system for restraining the vehicle until after all checks and engine thrust buildup were completed. The basic Saturn I holddown arm constrains the vehicle by clamping it between a fixed support and a movable jaw. The jaw is on a link pinned to rotate sufficiently to release the vehicle. There are three links in the jaw (restraining) system arranged so that with a small force provided by a pneumatic separator mechanism, the large loads of the vehicle can be restrained. Design details discussed are the link system, the separator, adjustments, and the energy absorber. The function of preloading is discussed. The secondary release system is described. Finally, the design differences between the Saturn I and the Saturn V arm are described
Recommended from our members
Intracellular localisation of mTHPC and effect of photodynamic therapy in cells of the mammalian peripheral nervous system
Fewer nerve-related side effects have been noted after treating head and neck cancer with photodynamic therapy (PDT) compared to conventional cancer therapy. Our aim is to investigate the biological basis for any such nerve-sparing effect. In this study the intracellular localisation and effect on cell viability of the photosensitiser meta-tetrahydroxylphenylchlorin (mTHPC) was investigated in cell culture models using peripheral nerve cells.
Primary cells from adult rat dorsal root ganglia (containing both neurons and glia) were used in these experiments. Localisation of mTHPC was detected using fluorescence and confocal microscopy. Levels of mTHPC fluorescence were quantified using digital image analysis. Immunocytochemistry with anti-?-III-tubulin and anti-S100 was used to distinguish neuronal and glial cell populations respectively. A cell-death assay using propidium iodide was used to evaluate neural cell susceptibility to PDT following incubation with mTHPC.
The results showed that mTHPC was localised in cytoplasmic regions of neurons and glia, but was not detected in neuronal axons. Necrotic cell death was detected after PDT in these neural cell types.
These results suggest that the cells of the peripheral nervous system are susceptible to PDT-mediated necrosis, but that the sparing of nerves observed during clinical PDT may be related to the heterogeneous distribution of mTHPC within neurons
- …