Standard environmental testing practices

Manual on procedural requirements for performing certain environmental tests on space flight equipment provides information for test equipment designers, quality control and production engineers. Contents of manual are summarized

Chick PTPσ regulates the targeting of retinal axons within the optic tectum

Chick PTP (cPTP), also known as CRYP, is a receptor-like protein tyrosine phosphatase found on axons and growth cones. Putative ligands for cPTP are distributed within basement membranes and on glial end feet of the retina, optic nerve, and optic tectum, suggesting that cPTP signaling is occurring along the whole retinotectal pathway. We have shown previously that cPTP plays a role in supporting the retinal phase of axon outgrowth. Here we have now addressed the role of cPTP within retinal axons as they undergo growth and topographic targeting in the optic tectum. With the use of retroviruses, a secretable cPTP ectodomain was ectopically expressed in ovo in the developing chick optic tectum, with the aim of directly disrupting the function of endogenous cPTP. In ovo, the secreted ectodomains accumulated at tectal sites in which cPTP ligands are also specifically found, suggesting that they are binding to these endogenous ligands. Anterograde labeling of retinal axons entering these optic tecta revealed abnormal axonal phenotypes. These included the premature stalling and arborization of fibers,excessive pretectal arbor formation, and diffuse termination zones. Most of the defects were rostral of the predicted termination zone, indicating that cPTP function is necessary for sustaining the growth of retinal axons over the optic tectum and for directing axons to their correct sites of termination. This demonstrates that regulation of cPTP signaling in retinal axons is required for their topographic mapping, the first evidence of this function for a receptor-like protein tyrosine phosphatase in the retinotectal projection

Detection of inflammatory bowel disease: diagnostic performance of cross-sectional imaging modalities

Different cross-sectional imaging techniques can be used as a diagnostic tool for the evaluation of inflammatory bowel disease (IBD). In this report the diagnostic performances of ultrasonography, magnetic resonance imaging and computed tomography in the detection of IBD and the evaluation of known IBD are described, together with a short update on patient preparation and imaging technique of the respective modalities discussed

The rehabilitative value of sub-economic housing as illustrated by Schauder Township, Port Elizabeth, Cape Province, Union of South Africa, 1938-1948

[From Introductory discussion]. The modern approach to any sociological problem is characterised by the attempt to analyse the contributory factors in such a way that their inter-active association is clearly discernible. The simple concept of "single cause and effect" is now recognised to be a traversity of social fact. Social Pathology, therefore, may be said to attempt to isolate the multiple factors involved in a given situation, and to endeavour to determine thelr mode of inter-action in order that remedial techniques may be applied effectively. Slum conditions are obviously pathologic, by which it is understood that the environment imposes strains upon the individual to which there is ineffective adjustment. The rehabilitation of such a population would involve the converse process, restoring individuals to a condition where they are able to cope in every respect with the demands of life at their respective class levels. It is very rare indeed that only a single factor is involved in a social pathological condition and for this reason it is quite possible that one- sided efforts at rehabilitation - such as the attempt to re-house ALL slum dwellers in sub-economic houses - have a tendency to increase the pathology in another direction. Rehabilitation must therefore be based on multi-factorial analysis in which allowance is, as far as possible, made for the inter-connection of each of the individual deviations from the normal. The aim of this thesis is to evaluate the effect of good housing conditions on the 2335 Coloured slum families re-housed in sub-economic houses at Schauder Township, Port Elizabeth, from the time that these houses were first available for occupancy

Rigid ball-polyhedra in Euclidean 3-space

A ball-polyhedron is the intersection with non-empty interior of finitely many (closed) unit balls in Euclidean 3-space. One can represent the boundary of a ball-polyhedron as the union of vertices, edges, and faces defined in a rather natural way. A ball-polyhedron is called a simple ball-polyhedron if at every vertex exactly three edges meet. Moreover, a ball-polyhedron is called a standard ball-polyhedron if its vertex-edge-face structure is a lattice (with respect to containment). To each edge of a ball-polyhedron one can assign an inner dihedral angle and say that the given ball-polyhedron is locally rigid with respect to its inner dihedral angles if the vertex-edge-face structure of the ball-polyhedron and its inner dihedral angles determine the ball-polyhedron up to congruence locally. The main result of this paper is a Cauchy-type rigidity theorem for ball-polyhedra stating that any simple and standard ball-polyhedron is locally rigid with respect to its inner dihedral angles.Comment: 11 pages, 2 figure

The Signs of Life Detector (SOLID): An Instrument to Detect Molecular Biosignatures on Mars

The case for life on Mars grows stronger. Investigations at Gale Crater by Curiosity have revealed fine-grained sedimentary rocks inferred to represent an ancient lake environment suited to support life. In addition, Curiosity tentatively found a heterogeneous distribution of organic carbon within these sediments, consistent with the detection of native organic C in Mars meteorites. Furthermore, modern potentially habitable environments have been recognized on Mars including the N. Polar region visited by Phoenix, gully features suggesting modern water flows, and RSLs that occur seasonally suggest liquid processes. The time is ripe for missions to Mars incorporating a search for biochemical evidence of life