Analysis of fracture induced scattering of microseismic shear-waves

Fractures are pervasive features within the Earth’s crust and have a significant influence on the multi-physical response of the subsurface. The presence of coherent fracture sets often leads to observable seismic scattering enabling seismic techniques to remotely locate and characterise fracture systems. In this study, we confirm the general scale-dependence of seismic scattering and provide new results specific to shear-wave propagation. We do this by generating full waveform synthetics using finite-difference wave simulation within an isotropic background model containing explicit fractures. By considering a suite of fracture models having variable fracture density and fracture size, we examine the widening effect of wavelets due to scattering within a fractured medium by using several different approaches, such as root-mean-square envelope analysis, shear-wave polarisation distortion, differential attenuation analysis and peak frequency shifting. The analysis allows us to assess the scattering behavior of parametrised models in which the propagation direction is either normal or parallel to the fracture surfaces. The quantitative measures show strong observable deviations for fractures size on the order of or greater than the dominant seismic wavelength within the Mie and geometric scattering regime for both propagation normal and parallel to fracture strike. The results suggest that strong scattering is symptomatic of fractures having size on the same order of the probing seismic wave

Discovery and functional prioritization of Parkinson's disease candidate genes from large-scale whole exome sequencing.

BACKGROUND: Whole-exome sequencing (WES) has been successful in identifying genes that cause familial Parkinson's disease (PD). However, until now this approach has not been deployed to study large cohorts of unrelated participants. To discover rare PD susceptibility variants, we performed WES in 1148 unrelated cases and 503 control participants. Candidate genes were subsequently validated for functions relevant to PD based on parallel RNA-interference (RNAi) screens in human cell culture and Drosophila and C. elegans models. RESULTS: Assuming autosomal recessive inheritance, we identify 27 genes that have homozygous or compound heterozygous loss-of-function variants in PD cases. Definitive replication and confirmation of these findings were hindered by potential heterogeneity and by the rarity of the implicated alleles. We therefore looked for potential genetic interactions with established PD mechanisms. Following RNAi-mediated knockdown, 15 of the genes modulated mitochondrial dynamics in human neuronal cultures and four candidates enhanced α-synuclein-induced neurodegeneration in Drosophila. Based on complementary analyses in independent human datasets, five functionally validated genes-GPATCH2L, UHRF1BP1L, PTPRH, ARSB, and VPS13C-also showed evidence consistent with genetic replication. CONCLUSIONS: By integrating human genetic and functional evidence, we identify several PD susceptibility gene candidates for further investigation. Our approach highlights a powerful experimental strategy with broad applicability for future studies of disorders with complex genetic etiologies

MATHEMATICAL BASIS FOR THREE DIMENSIONAL CIRCULAR INTERPOLATION ON CNC MACHINES

<p>ENGLISH ABSTRACT: The control units of numerically controlled manufacturing machines allow the programmer only a limited number of mathematical functions with which programmes can be written. Despite these limitations it is now possible to write programmes with which three dimensional (3D) circular interpolation can be performed directly on the .machines. The necessary mathematical techniques to perform 3D circular interpolation directly on the machines are deduced, although somewhat roundabout to overcome the programming limitations. The main programming limitations as well as cutter speed limitations are indicated.</p><p>AFRIKAANSE OPSOMMING: Die beheereenhede van numeriesbeheerde vervaardigingsmasjiene beskik:oor 'n beperkte aantal wiskundige funksies wat tot die beskikking van die programmeerder gestel word om programme mee te skryf. Selfs met .hierdie beperkings is dit nou moontlik om programme te skryf waarmee driedimensionele (3D) sirkelinterpolasie direk op die masjiene uitgevoer kan word. Die nodige wiskundige tegnieke waarmee 3D sirkelinterpolasie gedoen kan word, al is dit 'n effens omslagtige manier om die beperkings te oorkom, word afgelei. Die belangrikste programmeringsbeperkings asook snyspoedbeperkings word aangetoon.</p&gt

SILINDRIESE INTERPOLASIE

<p>ENGLISH ABSTRACT: In the manufacturing process of cylindrical cams with numerically controlled milling machines, the programming as well as the machining of accurate profiles normally turn out to be problematic. In an effort to overcome some of these problems the machine tool builder, MARO (Germany), had during 1990, sup-plemented its numerically controlled units with an option with which cylindrical interpolation is made possible. With this option programming is considerably simplified in some cases, but serious limitations necessitate in many instances that the option cannot be applied at all. The limitations of the option and how to overcome them, are illustrated and discussed in a typical programming example.</p><p>AFRIKAANSE OPSOMMING: In die vervaardigingsproses van silindriese nokke m.b.v. numeriesbeheerde freesmasjiene, lewer die programmering sowel as die masjinering van akkurate profiele normaalweg verskeie probleme op. In 'n poging om van sommige van hierdie probleme ontslae te raak, het die masjienvervaardiger MARO (Duitsland) vir sy numeriesbeheerde eenhede 'n nuwe opsie in 1990 bygevoeg waarmee silindriese interpolasie moontlik gemaak word. Met hierdie opsie word programmering in bepaalde gevalle aansienlik vereenvoudig, maar ernstige beperkings noodsaak in baie gevalle dat die opsie glad nie gebruik kan word nie. Die beperkings van die opsie en hoe dit oorkom kan word, word in 'n tipiese programmeringsvoorbeeld geIllustreer en bespreek.</p&gt

DIE ONTWTKKELING VAN 'N PARAMETRIESE MODEL VIR DIE SNY VAN RUIMTES SODS DIE VAN MARGAlUENBAKKIES

<p>ENGLISH ABSTRACT: When three dimensional machining is performed with a numerically controlled milling machine, then it is necessary to make use of cutter centre point programming because radius correction for these machines is possible in two dimensional context only. With ,:he rapid development of numerically com:rolled units it is possible now to use parameter programming for the development of three dimensional spaces which was possible only wi til computer aided design software some two years ago. An exceptional visualization of .the relationship between cutting surface and cutter position as well as a sound mathematical background is necessary to enable accurate programming of three dimensional spaces.</p><p>AFRIKAANSE OPSOMMING:Wanneer driedimensionele snywerk met 'n numeriesbeheerde freesmasjien gedoen word, is dit nodig om van snyermiddelpuntprogrammering gebruik te maak, omdat snyerradiuskorreksie vir hierdie masjiene slegs in tweedimensionele verband bestaan. As gevolg van die snelle ontwikkeling van numeriesbeheerde eenhede is di t nou moontlik om met behulp van parameterprogrammering driedimensionele ruimtes te ontwikkel wat twee jaar gelede slegs met rekenaargesteunde ontwerpprogrammatuur moontlik was. Vir die akkurate programmering van driedimensionele ruimtes is 'n besondere visualisering van die verband tussen snyvlak en snyerposisie, sowel as 'n grondige wiskundige agtergrond, nodig.</p&gt

Views of Zulus and Southern Sothos on immunisation

The promotion of good health and the prevention of disease are two of the aims of community health care that can, to a large extent be realised by means of immunisation. Immunisation does not only make it possible to control the spread of a number of infectious diseases, but also enhances the overall health status of a community

THE DEVELOPMENT OF A COMPUTER DRIVEN JIGSAW

<P>ENGLISH ABSTRACT: With a jigsaw, sharp inside corners can only be sawn out if the blade of the jigsaw is lifted out of the material and the corner is approached from two different sides. For the blade to be able to re-enter the material no material must be present at the entry point. The most important feature of an automated jigsaw is that it should be able to round off inside corners on a contour and automatically return to these corners to remove material left between the round off and the contour. With this development project an automated jigsaw machine was designed, built and tested. Emphasis fell on the development of software that enables one to draw contours that need to be sawn out, change these contours into cutter paths for the jigsaw and transform the cutter paths into digital format necessary to control the jigsaw machine via the parallel port of a personal computer.</P><P>AFRIKAANSE OPSOMMING: ‘n Figuursaag kan slegs skerp binnehoeke saag as die lem uit die materiaal uitgelig word en die hoek van twee kante af gesaag word. Waar die lem weer in die materiaal ingaan, mag geen materiaal aanwesig wees nie. Die belangrikste eienskap van ‘n ge-outomatiseerde figuursaag is dat kontoere so gesaag moet word dat binnehoeke afgerond kan word en die materiaal tussen die afronding en die gewensde kontoer outomaties verwyder moet word. Met hierdie ontwikkelingsprojek, is ‘n ge-outomatiseerde figuursaag ontwerp, gebou en getoets. Die klem van die projek val op die ontwikkeling van sagteware waarmee kontoere wat uitgesaag moet word, geteken kan word, omgeskakel kan word in ‘n snyerpad vir die saaglem en gebruik kan word vir digitale beheer van die saagmasjien deur gebruik te maak van die parallelpoort van ‘n persoonlike rekenaar.</P&gt

Differential effect of ultraviolet light on the induction of simian virus 40 and a cellular mutator phenotype in transformed mammalian cells

UV irradiation of simian virus 40 (SV40)-transformed human and hamster cells induced them both to express a mutator phenotype and to produce SV40. The mutator could also be activated indirectly by transfecting unirradiated cells with UV-damaged calf thymus DNA. In contrast, UV-damaged exogenous DNA failed to rescue SV40 from unirradiated transformed cells. These results suggest that the expression of transforming viruses and of cellular mutator functions is regulated by at least partially independent mechanisms. Unlike the activation of a cellular mutator phenotype, the rescue of SV40 from virus-transformed mammalian cells by UV light might require that the integrated viral DNA and/or specific cellular sequences are directly damaged. © 1985.SCOPUS: ar.jinfo:eu-repo/semantics/publishe